bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of catecholamines on Na—K transport and membrane potential in rat soleus muscle
Authors: Clausen Torben , Flatman John A.
Published: December 2014

1. The action of catecholamines on the transport and the distribution of Na and K and the resting membrane potential (EM) has been investigated in soleus muscles isolated from fed rats.

2. In a substrate‐free Krebs—Ringer bicarbonate buffer adrenaline (ADR) (6 × 10−6
M) increased 22Na efflux by 83%, 42K influx by 34%, and EM by 10%. Similar effects were exerted by noradrenaline (NA), phenylephrine, salbutamol and isoprenaline. The effects of ADR on Na—K transport and EM were suppressed by ouabain (10−3
M) and propranolol (10−5
M), but not by thymoxamine (10−5
M) or tetracaine (10−4
M).

3. Following 90 min of incubation in the presence of ADR (6 × 10−6
M), the intracellular K/Na‐ratio was increased threefold. NA produced almost the same change, and both catecholamines seem to induce a new steady‐state distribution of Na and K which can be maintained for several hours in vitro.

4. The effect of ADR on 22Na efflux and EM could be detected at concentrations down to 6 × 10−9 and 6 × 10−10
M, respectively, and half‐maximum increase was obtained at around 2 × 10−8
M. NA was at least one order of magnitude less potent.

5. The effect of low concentrations of ADR on 22Na efflux was potentiated by theophylline (2 m
M). When added together, dibutyryl‐cyclic AMP and theophylline mimicked the action of ADR on 22Na efflux, 42K influx, Na/K content and EM. Ouabain (10−3
M) also suppressed the effect of dibutyryl‐cyclic AMP and theophylline on Na—K transport.

6. Following the addition of ouabain (10−3
M), EM rapidly dropped from a mean of ‐71 to ‐63 mV, and then showed a slow linear fall for up to 4hr.

7. The hyperpolarization induced by ADR was associated with a decrease in membrane conductance, 22Na influx and 42K efflux. The time course and the response to ouabain suggests that all of these effects are secondary to stimulation of the active coupled transport of Na and K.

8. It is concluded that in rat soleus muscle, the active Na—K transport is electrogenic and susceptible to stimulation by catecholamines via beta‐adrenoceptors. This effect is mediated by adenyl cyclase activation and may account for the increase in EM and the intracellular K/Na ratio.
Endocytosis and immunoglobulin transport across the small intestine of the new‐born pig
Authors: Burton K. A. , Smith M. W.
Published: December 2014

1. Measurements of porcine and human IgG transport across the small intestine of the new‐born pig have been made in vivo and related to the amount of endocytosis taking place.

2. The amount of immunoglobulins transported, following intraduodenal administration to conscious animals, is directly related to the degree of endocytosis which these proteins produce. Administration of protein in amounts sufficient to cause a maximal endocytotic response causes saturation of the protein transporting process.

3. Absorption of small amounts of human IgG from the small intestine can be accelerated by the addition of sow colostrum or porcine IgG in quantities sufficient to stimulate endocytosis. These effects disappear when the amount of human IgG administered is itself sufficient to fully stimulate endocytosis.

4. Preferential transport of porcine over human IgG can be demonstrated when both are given as a single solution to individual pigs. The degree of preference is, however, small in relation to the total amount of immunoglobulin transported.

5. The initial formation of endocytotic vacuoles in the pig intestine seems, unlike the situation in rats and mice, to provide a major route for the trans‐cellular movement of macromolecules including immunoglobulins. Present evidence suggests that, though sow colostrum can on occasion stimulate such transport, it does so merely by acting as a protein‐containing solution to increase the amount of endocytosis taking place.
Training induced adaptation of skeletal muscle and metabolism during submaximal exercise
Authors: Henriksson Jan
Published: December 2014

1. Six subjects were trained using a one‐leg bicycle exercise for 2 months. The untrained leg served as control. After the training period, muscle oxidative capacity, determined as succinate dehydrogenase activity, was 27% higher in the trained (as opposed to the control) leg (P < 0·05).

2. When the subjects in this situation performed a 1 h two‐legged submaximal bicycle exercise bout (150‐225 W), determinations of VO2 of the single leg (leg blood flow × (A—V)O2 difference) revealed that they appeared to choose to work harder with their trained than with their untrained leg, so as to make the relative loads for the two legs the same.

3. Determinations of O2 and CO2 on femoral arterial and venous blood demonstrated that the
R.Q. was lower in the trained as compared to the untrained leg, 0·91 cf. 0·96 (10 min) and 0·91 cf. 0·94 (50 min) (P < 0·05).

4. That metabolism of fat was more pronounced in the trained leg was further supported by the finding of a significant net uptake of free fatty acids in this leg only. Moreover, a lower release of lactate from the trained leg was demonstrated.

5. It is suggested that the shift towards a more pronounced metabolism of fat in the trained leg is a function of an increased muscle oxidative capacity.
A study of excitatory neuromuscular transmission in the bovine trachea
Authors: Cameron A. R. , Kirkpatrick C. T.
Published: December 2014

1. The excitatory innervation of bovine tracheal smooth muscle has been studied with the sucrose‐gap apparatus.

2. Single 2 ms electrical stimuli applied to the whole tissue excited intrinsic nerves, and produced a small transient depolarization of the smooth muscle, the excitatory junction potential (e.j.p.). The e.j.p. caused a twitch‐type contraction; twitches and e.j.p.s summated during repetitive stimulation but facilitation was not observed, and action potentials were never elicited.

3. The effects of electrical stimulation could be abolished by atropine (5 × 10−7 mol/l) and augmented by neostigmine (4 × 10−6 mol/l), and were mimicked by exogenous acetylcholine (1·0 μg/ml).

4. With the electron microscope, the density of innervation was found to be low (one axon per ninety smooth muscle cells). Axons were found in small groups in the clefts between bundles of cells, but no axons penetrated within the muscle bundles. Naked axon varicosities containing agranular vesicles were seen, but no axon approached within 200 nm of a smooth muscle cell.

5. It is difficult to reconcile the sparsity of innervation with the dependence of the tissue on nerve excitation to initiate activity.
Transmission from photoreceptors to ganglion cells in turtle retina
Authors: Baylor D. A. , Fettiplace R.
Published: December 2014

1. Synaptic transfer between photoreceptors and impulse‐generating cells was studied in isolated eyecups from turtles. Single red‐sensitive cones or rods were stimulated by current passed through an intracellular electrode, and impulses generated by the resulting synaptic action were recorded with an external micro‐electrode. This technique permits study of retinal transmission without the operation of the visual transduction mechanism. Antidromic stimulation of the optic nerve indicated that most of the impulse‐generating cells were ganglion cells.

2. Individual ganglion cells responded transiently to changes in the membrane potential of a receptor and could be classified into three groups on the basis of the direction of the effective change in potential. Off centre ganglion cells responded selectively to depolarizations of a receptor, while on centre ganglion cells responded selectively to hyperpolarizations. On‐off ganglion cells responded to both depolarizations and hyperpolarizations of a receptor.

3. Ganglion cells gave the same pattern of response to electrical hyperpolarization of a receptor and to light in the centre of their receptive fields. Subthreshold depolarizing currents passed in a receptor antagonized the ganglion cell's response to light, and subthreshold hyperpolarizing currents reinforced the response. These observations are consistent with the view that the hyperpolarization generated by visual transduction is responsible for regulating the release of transmitter at the first retinal synapse.

4. When a receptor was stimulated with weak current pulses of fixed intensity the number and latency of the ganglion cell impulses fluctuated randomly in successive trials. The relation between the fraction of trials yielding a response and the stimulus intensity was broad. These results indicate that the link between retinal input and output is noisy.

5. In the most sensitive pairs of cells, a response of one or more impulses could be obtained in half the trials with a current of about 2 × 10−11 A, which changed the potential of the receptor by 1‐2 mV. A current of similar magnitude would be developed by about 130 photoisomerizations in a red‐sensitive cone or 50 photoisomerizations in a rod.

6. Dim background light producing a steady hyperpolarization of a few millivolts in the rods raised the threshold for electrically‐evoked transmission from a rod to a ganglion cell. In experiments on red‐sensitive cones, background light raised the threshold in the off pathway, in which depolarization was the effective stimulus, and lowered the threshold in the on pathway, in which hyperpolarization was the effective stimulus. These changes in sensitivity were not accompanied by obvious changes in the input resistance of the stimulated receptor. Regulation of retinal sensitivity in background light thus involves changes in synaptic transfer as well as changes in the sensitivity of the visual transduction mechanism.
Load clamp analysis of maximal force potential of mammalian cardiac muscle.
Authors: Brutsaert D L , Housmans P R
Published: December 2014

1. Abrupt alterations in load (load clamps) have been imposed on cat papillary muscle during isotonic shortening and relaxation of afterloaded twitch and tetanic contractions, to assess the maximal force potential for a given contractile state. 2. These load clamps were accompanied by an initial fast lengthening reflecting an undamped series compliance. Even when exceeding isometric twitch and tetanic force, these loads could be borne for a considerable time, accompanied by a slower lengthening after the initial extension of the series compliance. At sufficiently high loads the muscle was pulled out very rapidly; a maximal supra‐isometric force potential was defined as the load the muscle could bear momentarily and this was measured at times throughout contraction and relaxation. 3. This maximal force potential was determined at different initial muscle lengths. Depending on the instantaneous loading conditions, various length‐force relations were obtained from : (a) peak force values of isometric twitches at different starting lengths, (b) the shortest length reached during after loaded isotonic twitches, and (c) the forces obtained in overloaded isotonic twitch contractions. 4. These results are consistent with a crossbridge model in which the delayed lengthening during isotonic overloading is due to back rotation and detachment of attached crossbridges and in which the inital phase of spontaneous isotonic relaxation is governed by the same mechanism.
Morphology and responses to light of the somata, axons, and terminal regions of individual photoreceptors of the giant barnacle
Authors: Hudspeth A. J. , Stuart Ann E.
Published: December 2014

1. The median eye of the giant barnacle, B. nubilus, comprises four large photoreceptor neurones which are visible under the dissecting microscope for almost their entire length. We have studied the structure of, and the responses to light recorded in, the somata, axons, and terminal regions of these neurones.

2. The photoreceptor somata, each 40‐70 μm in diameter, extend numerous light‐sensitive dendritic processes whose membranes form rhabdomeric microvilli. Recordings from the soma show that dim light evokes a steady, noisy depolarization; brighter light elicits a transient depolarization which decays to a maintained plateau, followed by a hyperpolarization when the light is turned off.

3. Light‐induced voltage changes spread decrementally along the photoreceptor axons, which average 10 mm in length and 25 μm in diameter. In distal parts of the axon, near the presynaptic terminals, depolarizations and hyperpolarizations can be as large as 50% or more of their values in the soma.

4. There is no demonstrable electrical coupling between photoreceptor neurones as shown by simultaneous recordings from two receptor somata or axons.

5. Each photoreceptor axon enters the mid line commissure of the supraoesophageal ganglion, bifurcates, and arborizes in a restricted zone of neuropil in each hemiganglion. The large size of the terminal processes of these neurones and their characteristic cytoplasmic inclusions enable one to trace them with the electron microscope as they branch in the neuropil.

6. The terminal processes subdivide and end in 1‐3 μm diameter branches which are the sites of apparently chemical synapses. Vesicle‐containing, presynaptic loci on these processes of the receptor cell are invariably apposed to two post‐synaptic processes from cells as yet unidentified.
Analysis of the onset phase of olfactory bulb unit responses to odour pulses in the salamander
Authors: Kauer John S. , Shepherd Gordon M.
Published: December 2014

1. A method for delivering odour pulses of controlled onset, steady plateau and abrupt termination, has been developed and applied to a single unit study of mitral cell responses in the olfactory bulb of the salamander. The pulses have been monitored during the experiments near the site of stimulation on the olfactory mucosa.

2. Responses have been categorized as excitatory or suppressive based on the initial response to the odour pulse.

3. Initially excitatory responses had sustained discharges near threshold. With increasing concentration, the discharge changed to a brief burst followed by suppression. The briefest latency of a unit response was 120 msec, using stimulation of medium concentration, after the start of the pulse; the majority of units appeared to be excited within 200‐300 msec. Ramp stimuli gave increasing periods of excitation as the rise time of the odour front became less abrupt.

4. Initially suppressive responses showed suppression at all levels of concentration. The majority of units appeared to have an onset of suppression about 300‐400 msec after the start of the pulse.

5. These basic responses, involving suppression or excitatory—suppressive sequences, can be correlated with some basic properties of the synaptic circuits in the olfactory bulb. The time courses of the initial responses appear to be within the time periods of the inhalation cycle of the salamander, and therefore may reflect mechanisms of processing of natural olfactory stimuli.
Effect of 4‐aminopyridine on release of noradrenaline from the perfused cat spleen by nerve stimulation.
Authors: Kirpekar M , Kirpekar S M , Prat J C
Published: December 2014

1. 4‐aminopyridine (4‐AP, 1 mM) increased noradrenaline (NA) output from the perfused cat spleen at 5 Hz by about fivefold. Enhancement of NA release by 4‐AP was reversible. Output of NA induced by potassium was not affected. 2. NA output was doubled at low concentrations (0.1‐‐0.3 mM) of 4‐AP, but maximal effect was obtained at 1‐‐3 mM. At 10 mM, it induced spontaneous release of NA which was insensitive to calcium. 3. Insignificant outputs obtained at 5 Hz in 0.1 and 0.3 mM calcium‐Krebs solution were markedly enhanced by 4‐AP. 4‐AP enhanced release at all calcium concentrations up to 5 mM, but maximum output was obtained at 2.5 mM. 4. 4‐AP at pH 8.5 was more effective in enhancing NA release than at pH 7.4. 5. 4‐AP increased the recovery of intra‐arterially infused NA from the control 26 to 47%. 6. 4‐AP did not affect release of catecholamines (CA) from the perfused cat adrenal gland by acetylcholine (ACh). 7. It is suggested that 4‐AP inactivates potassium current in sympathetic nerves and prolongs the duration of the action potential, thereby allowing a greater influx of calcium ions into the neurone to enhance release of NA.
The effect of foreign cations, pH and pharmacological agents on the ionic permeability of an excitatory glutamate synapse.
Authors: Anwyl R
Published: December 2014

1. Voltage clamp studies of the post‐synaptic membrane of the insect neuromuscular junction have shown that normal amplitude glutamate currents could be recorded for a limited time when external Na was completely replaced by Ca, Li, ammonium, methylamine and guanidine. No change in the reversal potential of the glutamate current was observed when Na was replaced by these ions. It is suggested that the glutamate ionic channel has a similar permeability to Na and to these foreign cations, although the foreign ions cause a longer‐term block of the permeability increase or receptor function. 2. Procaine, pentobarbitone, 2‐4‐6‐triaminopyrimidine, high and low pH and low temperature reduced the synaptic ionic permeability but did not alter the ratio of the conductance increase of Na to K (delta g Na/delta gK). 4‐Aminopyridine and TEA did not reduce the synaptic ionic permeability. 3. The 3. The properties of the synaptic ionic channels resemble the tight junction transepithelial ionic channels of the mammalian gall‐bladder, but are very different from the Na and K non‐synaptic channels of axons. It is suggested that Na and K normally pass through a single relatively large channel containing strong proton accepting acidic ligands which render the channel cation selective.
Vagal control of lower oesophageal sphincter motility in the cat
Authors: Gonella J. , Niel J. P. , Roman C.
Published: December 2014

1. The effects of vagal efferent fibre stimulation on the smooth muscle of the lower oesophageal sphincter have been studied on the anaesthetized animal and on the isolated and perfused organ.

2. In both muscle layers (longitudinal and circular) vagal stimulation elicits two types of electromyographic (e.m.g.) potentials: (a) excitatory junction potentials (e.j.p.s) where there is a depolarization of the smooth muscle fibres. E.j.p.s can give rise to spike potentials inducing a contraction of the sphincter; (b) inhibitory junction potentials (i.j.p.s) where there is hyperpolarization of the smooth muscle fibres, often followed by a transient depolarization which may initiate spikes (post‐inhibitory rebound).

3. Pure i.j.p.s are observed after atropine treatment which suppresses e.j.p.s. Under these conditions, a long lasting vagal stimulation induces a long duration hyperpolarization concomitant with an opening of the lower oesophageal sphincter followed after the cessation of stimulation by a powerful rebound leading to a strong contraction which closes the sphincter.

4. Several arguments, pharmacological (action of acetylcholine (ACh), atropine and hexamethonium) and physiological (threshold and latency of responses) lead to the following conclusions.

Preganglionic vagal fibres are cholinergic and they activate (a) intramural excitatory cholinergic neurones; (b) intramural non‐adrenergic inhibitory neurones (purinergic neurones). Preganglionic fibres leading to inhibition have a higher threshold than those leading to excitation.

Both excitatory and inhibitory pathways are interconnected inside the intramural network. In particular, activation of intramural inhibitory neurones, by relaxing the oesophagus orally to the lower oesophageal sphincter, inhibits intramural excitatory neurones and subsequently blocks vagal excitatory responses.

5. Two functions may be attributed to the vagal extrinsic innervation: (a) closure of the lower oesophageal sphincter by maintaining the basal tone of the sphincter; this would imply that at rest the inhibitory control is supplanted by the excitatory one; (b) sphincter opening during swallowing by suppressing the excitatory stimulus and reinforcing the inhibitory one (it may be recalled that after bilateral vagotomy, swallowing is no longer followed by a relaxation of the sphincter).
Pancreatic acinar cells: acetylcholine‐evoked electrical uncoupling and its ionic dependency
Authors: Iwatsuki N. , Petersen O. H.
Published: December 2014

1. Isolated segments of mouse or rat pancreas were placed in a Perspex bath through which physiological saline solutions were circulated. Intracellular recordings from surface acini were made by inserting up to three separate micro‐electrodes into neighbouring cells within the same acinus. Through one of these electrodes current pulses could be injected. Electrical coupling between the cells could be continuously assessed. The acinus under investigation was stimulated by iontophoresis of ACh from an extracellular micropipette.

2. During resting conditions all cells within an acinus were fully electrically coupled. A 5‐10 sec pulse of a relatively large iontophoretic ACh ejecting current, causing initially the well characterized surface cell membrane depolarization and resistance reduction, was followed by a marked electrical uncoupling of neighbouring cells. In some cases one cell was clearly being isolated equally from the two other cells impaled, in other cases the cell into which current pulses were injected was becoming more isolated from one of the neighbouring cells than from the other one.

3. The ACh‐evoked electrical uncoupling was completely reversible and could be repeatedly observed in the same cell.

4. The electrical uncoupling in response to short pulses of ACh (5‐10 sec) was not affected by even prolonged (up to 50 min) exposure to Ca‐free solution containing EGTA.

5. ACh‐evoked uncoupling (short pulses) was not reduced about 5 min after introduction of Mn (2 m
M), Ni or Co (5 m
M). Mn thereafter gradually reduced and finally (after about half an hour) abolished the ACh‐evoked uncoupling. Ni and Co gradually enhanced the uncoupling response. The blocking effect of Mn on the ACh‐evoked uncoupling occurred much faster in the absence of superfusion fluid Ca.

6. During a period of sustained ACh stimulation sustained electrical uncoupling was observed. If Ni or Co (5 m
M) was introduced during such a stimulatory period the cells recoupled. This effect of Ni and Co was immediate and fully reversible.

7. The uncoupling responses to short pulses of ACh was not reduced immediately after replacing superfusion fluid Na by Tris at a time when the surface cell membrane depolarization and resistance reduction was already severely reduced. Thereafter a gradual slow reduction of the ACh‐evoked uncoupling was observed. This did not occur if Na was replaced by Li.

8. It is concluded that the Ca needed to raise [Ca2+]i sufficiently to cause electrical uncoupling comes from the cells in cases of uncoupling evoked by short pulses of ACh, but from the external solution in cases of sustained uncoupling evoked by sustained stimulation of ACh.
Modification of visual response properties in the superior colliculus of the golden hamster following stroboscopic rearing
Authors: Chalupa Leo M. , Rhoades Robert W.
Published: December 2014

1. Visual response properties of superior collicular neurones were investigated in golden hamsters reared from birth to adulthood in a stroboscopic environment.

2. In comparison to normally reared animals, there was a marked decrease in the incidence of directionally selective cells in the colliculus of the strobe‐reared hamsters. This effect was apparent when directional selectivity was determined by either the null criterion or a statistical measure. The reduction in directionally selective cells was found in both superficial and the deep layers of the colliculus.

3. Neurones in strobe‐reared hamsters also exhibited a different speed preference distribution from that obtained for normal animals, in that more cells in the restricted hamsters responded only to slow velocities, and less were broadly tuned with regard to the speed of moving stimuli.

4. In addition to the effects obtained in dynamic response properties, there were also changes in the static response properties of superior collicular neurones. These were an increase in the proportion of cells whose responses were not affected by changing the size of a stationary flashed stimulus, and a concomitant decrease in the number of cells demonstrating either partial or complete suppression when the size of a flashed stimulus exceeded the boundaries of the receptive field activating region. Furthermore, while all cells which responded to stationary stimuli in normal animals yielded only phasic responses to stimulus onset and/or offset, in the strobe‐reared hamsters eight cells were encountered which responded in a sustained fashion to stationary spots.

5. There was no indication of an increased responsivity in the restricted animals to strobe stimulation, even when a strobe rate identical to that employed in the rearing environment was employed.

6. The results were interpreted as indicating a disruption of normal visual functional organization in the hamster's superior colliculus by an aberrant visual input during development.
Significance of 2,4‐dinitrophenol action on spinal motoneurones.
Authors: Krnjević K , Puil E , Werman R
Published: December 2014

1. Extracellular iontophoretic applications of DNP lead to an increase in the membrane conductance of cat spinal motoneurones, manifested by a rise in input conductance, a slower rate of rise and fall of action potentials, and occlusion of the afterhyperpolarization. 2. There is also some hyperpolarization, but the reversal potential for the action of DNP is only about 12 mV more negative than the resting potential. 3. These effect of DNP can be abolished or significantly reduced by intracellular injections of EGTA. On the other hand, DNP can partly reverse the decreased conductance and the depression of the slow afterhyperpolarization caused by EGTA. 4. Intracellular injections of DNP also induce a rise in input conductance; when repeated, they tend to have a depolarizing effect, mainly irreversible. 5. It is concluded that DNP acts principally inside the motoneurone, by liberating bound internal Ca, the free Ca ions then raising membrane conductance, especially GK.
Surface charges and the effects of calcium on the frequency of miniature end‐plate potentials at the frog neuromuscular junction.
Authors: Madden K S , Van der Kloot W
Published: December 2014

1. When motor nerve terminals are slightly depolarized with increased [K+]o, progressive increases in [Ca2+]o raise min.e.p.p. frequencies until a maximum is reached; further increases then produce a depression (Cook & Quastel, 1973; Matthews & Wickelgren, 1977). 2. Increases in [Mg2+]o also produce the depression. 3. It has been suggested that the depression results from this sequence of events: (a) the divalent cations screen the fixed negative surface charges on the outer face of the nerve terminal, which (b) decreases the negativity of the surface potential, which (c) increases the voltage gradient within the membrane itself, which (d) tends to shut depolarization‐gated channels for Ca2+ entry, which (e) decreases min.e.p.p. frequency. 4. In agreement with the interpretation, in frog neuromuscular junctions slightly depolarized with 11 mM‐[K+]o, min.e.p.p. frequency is a monotonically increasing function of [Ca2+]o, as long as the sum of [Ca2+]o plus [Mg2+]o is kept constant. 5. The decrease in min.e.p.p. frequency caused by raising [Mg2+]o by 5 mM can be counterbalanced by raising [K+]o by about 9 mM. Using the Grahame equation (1947), assuming that the elevated divalent cations act solely by screening and have no effect on conductance, the negative surface charge is estimated to be roughly 1 electronic charge/75 A2.
Drinking and haemodynamic changes induced in the dog by intracranial injection of components of the renin‐angiotensin system.
Authors: Fitzsimons J T , Kucharczyk J
Published: December 2014

1. Intracranial injections of the individual components of the renin‐angiotensin system caused drinking in water‐replete dogs. 2. Angiotensin II was the most reliable, potent and rapidly acting intracranial dipsogen and elicited drinking in the absence of peripheral circulatory changes. After the highest dose of angiotensin II (10(‐9) mole) five dogs drank a mean amount of 380.0 +/‐ 88.6 ml. For the other components, the order of dipsogenic effectiveness was angiotensin I, synthetic renin substrate, and angiotensin III. 3. Isotonic saline, bradykinin (10(‐10) mole), eledosin‐hexapeptide (10(‐10) mole), oxytocin (10(‐10) mole) and prostaglandin F2alpha (1‐200 X 10(‐12) mole) were ineffective. 4. Intracranial renin (10 m‐u.) produced a mean intake of 445 +/‐ 152 ml. of water in eight dogs. 5. Dog renin substrate and synthetic renin substrate, injected intracranially in a dose of 10(‐10) mole, produced similar intakes of water but these amounts were very much less than the volume drunk in response to the same dose of angiotensin II. 6. None of the components injected into dipsogenically responsive sites in the brain caused changes in blood pressure, although the act of drinking itself produced a small rise. 7. Angiotensin II at the highest dose produced drinking when injected into the subfornical organ, preoptic region, anterior hypothalamus, lateral ventricle, third ventricle, ventral hippocampus and mid‐line thalamus. Negative sites were found in the caudate nucleus, fourth ventricle, mid‐brain, posterior thalamus, dorsal hippocampus, lateral hypothalamus and posterior hypothalamus. 8. After the lowest dose of intracranial angiotensin II (10(‐12) mole) only the preoptic region and subfornical orgal were responsive. These two sites were equally sensitive in terms of latency and amounts drunk at all doses injected. 9. Angiotensin did not necessarily have to reach a cerebral ventricle in order to cause drinking. 10. The dog resembles the rat in its responsiveness to the dipsogenic action of intracranial angiotensin II. The regions of the brain from which drinking can be elicited are more widespread than has been claimed by some in the rat.
The topographic organization of rhesus monkey prestriate cortex.
Authors: Essen D C , Zeki S M
Published: December 2014

1. The topographic organization of prestriate visual cortex in the rhesus monkey has been studied both anatomically, by determining the pattern of termination of fibres passing through the corpus callosum, and physiologically, in the same animals, by plotting receptive field positions for different recording sites. Results are displayed on two‐dimensional, "unfolded" maps of the cortex in the dorsal half of the occipital lobe. 2. Transcallosal fibres terminate in a narrow strip of cortex along the boundary between striate and prestriate areas and in a separate, broader, zone occupying much of the anterior bank of the lunate sulcus, the annectant gyrus, and the parietooccipital sulcus. The detailed pattern of inputs is highly complicated but shows considerable similarities from one animal to the next. 3. Physiological recordings confirmed earlier reports that regions where transcallosal fibres terminate correspond to representations of the vertical meridian in the visual field. This relationship is most precise along the striate‐prestriate boundary and along the boundary of area V3 farthest from V1; it is less precise within area V4, where the pattern of transcallosal inputs is more complex. 4. A distinct, topographically organized visual area, named V3A, was found in the region between areas V3 and V4 in the lunate and parieto‐occipital sulci. Area V3A differs from V2 and V3 in that both superior and inferior visual quadrants are represented in a single region of the dorsal occipital lobe. 5. The contralateral visual field is represented in a suprisingly complex fashion in areas V3A and V4. Within each area there are multiple representations of some, but perhaps not all, parts of the visual hemifield. It is unclear whether V3A and V4 should be more appropriately considered as sets of distinct sub‐areas, each representing only a portion of the hemifield, or as larger areas with complicated internal topographies. 6. Most cells in areas V2, V3 and V3A are orientation selective but not selective for stimulus colour or direction of movement. In contrast, area V4 contains a higher incidence of colour selective cells and a lower incidence of orientation selectivity. These results support the notion of a functional division of labour within the prestriate cortex.
Plasma vasopressin levels during hypoxaemia and the cardiovascular effects of exogenous vasopressin in foetal and adult sheep.
Authors: Rurak D W
Published: December 2014

1. Fotetal plasma vasopressin levels were measured by bio‐assay in chronically catheterized sheep from 110 to 145 days gestation. 2. In foetuses in good condition resting circulating vasopressin concentrations were generally undetectable (less than 5 micromicron./ml.). In 15% of the samples low concentrations (5‐10 micromicron./ml.) were observed. 3. Hypoxaemia in the foetus was caused by allowing the ewe to breathe 9% O2‐3% CO2 in N2 for 1 hr. Plasma vasopressin levels rose in the foetus to 119 +/‐ 32 micromicron./ml., whereas the hormone levels in the ewe were not routinely increased. In the foetus, the rise in plasma vasopressin levels was significantly related to the fall in pH and Pa, O2 during the hypoxia. 4. In foetuses in which the cervical vagosympathetic trunks were cut, the rise in plasma vasopressin levels (to 48 +/‐ 25 micromicron./ml.) during hypoxaemia was less than in intact foetuses. The increase was related only to the fall in arterial pH and the regression coefficient was less than in intact foetuses. 5. During hypoxaemia arterial pressure rose and heart rate fell in the normal foetuses. The rise in arterial pressure was greatest when the plasma vasopressin concentration was highest. 6. Spontaneous episodes of hypoxaemia (Pa, O2 less than 15 mmHg) and/or acidaemia (pH less than 7.30) occurred in four intact foetuses and four foetuses in which the cervical vagosympathetic trunks were cut; all of the latter lambs died in utero. Plasma vasopressin levels were elevated and the concentrations were inversely related to arterial pH. 7. Intravenous infusions of vasopressin to foetuses increased plasma vasopressin levels to 6‐202 micromicron./ml.; the rate of clearance of the hormone was three times that in adult ewes. There was a large increase in arterial pressure and bradycardia. The hypertensive effects of vasopressin were relatively much greater in the foetus than in adult ewes.
Effect of cholinergic antagonists on sympathetic ganglionic transmission of vasomotor reflexes from the carotid baroreceptors and chemoreceptors of the dog.
Authors: Henderson C G , Ungar A
Published: December 2014

1. In anaesthetized dogs the reflex vascular resistance changes in a perfused hind limb were studied following carotid baroreceptor or chemoreceptor stimulation. 2. The observed rises in resistance were sympathetically mediated and thus provided a means of studying the action of the cholinergic antagonists on the sympathetic ganglion transmission. 3. The reflex response to carotid baroreceptor stimulation produced by lowering the pressure in the carotid sinuses was abolished by hexamethonium bromide but not reduced by hyoscine methyl bromide. 4. The reflex response to carotid body chemoreceptor stimulation, by hypoxia, was not altered by hexamethonium bromide but was greatly reduced by the hyoscine methyl bromide. No reflex response was seen when both antagonists were present. 5. These results indicate that sympathetic ganglion synaptic transmission during the baroreceptor reflex is mediated by nicotinic receptor activation. The transmission evoked by chemoreceptor stimulation involves muscarinic receptors with a subsidiary nicotinic pathway. High doses of an antagonist were necessary to block the muscarinic component of transmission and this is discussed in relation to previous work. 6. No non‐cholinergic transmission of the reflex responses was observed.
Noise and relaxation studies of acetylcholine induced currents in the presence of procaine.
Authors: Marty A
Published: December 2014

1. The effects of procaine on the excitatory effects of acetylcholine (ACh) on Aplysia neurones were studied by analysing the current relaxations induced by voltage steps. Procaine was applied by perfusion and ACh was applied iontophoretically under two sets of experimental conditions designed to produce very different ACh concentrations at the membrane. 2. When ACh was applied at high concentration, the current relaxation following a hyperpolarizing step showed two components at procaine concentrations of about 2 X 10(‐5) M; a fast increase was followed by a slow decrease. At high procaine concentrations (greater than 10(‐4) M), the relaxation has only one component, corresponding to an exponential current decrease. 3. When ACh was applied at low concentrations, the current relaxation usually showed two components. At low procaine concentrations a fast increase was followed by a slower one; at higher procaine concentrations, a fast decrease preceded the slow increase. 4. All the results can be accounted for by assuming that procaine binds preferentially to the activated receptor‐channel complex and converts it into a non‐conducting complex. The association and dissociation constants were calculated to be (at 12 degrees C, ‐80 mV) 1.3 X 10(6) M‐1 sec‐1 and 10 sec‐1.
Influence of intermittent breathing on ventricular depolarization patterns in chelonian reptiles.
Authors: Burggren W W
Published: December 2014

1. Alterations between two quite distinct patterns of epicardial depolarization are associated with the normal occurrence of intermittent lung ventilation in both lightly anaesthetized and unrestrained, conscious turtles (Pseudemys scripta) and tortoises (Testudo graeca). 2. During apnoea depolarization sweeps from the left to the right over the ventricular surface at a conduction velocity of 0.15 m/sec. With the onset of lung ventilation the direction of depolarization propagation over the ventricle is reversed, and conduction velocity in the epicardium falls to 0.09 m/sec. 3. Vagal stimulation and acetylcholine produce a shift from the apnoea to the breathing pattern of depolarization in intact animals, while vagal sectioning and atropine abolish all shifts. Acetylcholine reduces conduction velocity but has no effect on the strength of contraction of isolated cardiac muscle strips from turtle hearts. Changes between the two patterns of ventricle depolarization are likely produced by vagal innervation of the rudimentary conduction system of the chelonian heart. 4. Experimental induction of the depolarization pattern of the ventricle normally evident during lung ventilation produces an improved separation of oxygenated and deoxygenated blood within the anatomically undivided chelonian ventricle. It is suggested that changes in ventricle depolarization patterns during intermittent lung ventilation may be an active component of the cardiovascular responses controlling intracardiac blood shunting in reptiles.
The equilibrium between metarhodopsin I and metarhodopsin II in the isolated frog retina
Authors: Baumann Ch.
Published: December 2014

1. Rapid and slow changes in the absorbance of isolated frog retinae produced by exposure to brief flashes were studied at temperatures between 5 and 30 °C.

2. Rapid changes observed at 475 nm consist of a transient increase of absorbance followed by an exponential decay to a new level of absorbance which is lower than before the flash exposure.

3. The new level of absorbance determines the initial conditions of slow changes following the rapid ones. At higher temperatures, the loss of absorbance during the rapid changes is greater than at lower temperatures. Accordingly, the slow reactions start at lower levels of absorbance when the temperature is high.

4. Quantitative analysis showed that the rapid reactions can be described in terms of two consecutive reactions followed by an equilibrium reaction: the light‐controlled formation of lumirhodopsin, decay of lumirhodopsin to metarhodopsin I, and the equilibrium reaction between the metarhodopsins I and II.

5. The slow absorbance changes observed in the visible (λ = 480 nm) are due to metarhodopsin I and to metarhodopsin III. Metarhodopsin I decays during the early phase of slow reactions but can noticeably influence the kinetics at lower temperatures.

6. The activation energy of the lumirhodopsin decay is 22.5 kcal/mole, that of the conversion of metarhodopsin I into metarhodopsin II is 30.1 kcal/mole. The entropy change associated with the metarhodopsin I‐II equilibrium amounts to +34 cal/mole. K.
On the receptors involved in the nervous control of salivary secretion by Nauphoeta cinerea Olivier.
Authors: House C R , Smith R K
Published: December 2014

1. It has been shown that the isolated salivary glands of Nauphoeta cinerea Olivier produce fluid secretion in response to nerve stimulation or bath applications of dopamine, noradrenaline, adrenaline and 5‐HT. These catecholamines, of which dopamine is the most potent, evoked maximal responses matching that to nerve stimulation whereas 5‐HT was less effective. 2. The receptors combining with 5‐HT could be distinguished from those for the catecholamines and the transmitter at this salivary neuroglandular junction. 3. The results of experiments where glands were stimulated by dopamine in the presence of noradrenaline or adrenaline suggested that there are receptors with specific binding sites for dopamine. 4. The effects of several antagonists (Ginsborg, House & Silinsky, 1976) of the hyperpolarizing responses from acinar cells to nerve stimulation and the above agonists have been examined. Phentolamine reversibly suppressed the secretory responses to these stimuli whereas methysergide had no effect and ergometrine elicited fluid secretion in a dose‐dependent manner.
Activation and inhibition of olfactory bulb neurones by anterior commissure volleys in the rabbit.
Authors: Mori K , Takagi S F
Published: December 2014

1. In the rabbit olfactory bulb, analysis has been carried out on intracellular potentials recorded from mitral cells and neurones in the granule cell layer (g.c.l. cells) in addition to the extracellular field potentials in the olfactory bulb elicited by anterior commissure (a.c.) stimulation. 2. Most mitral cell recordings showed i.p.s.p.s with latency of 7‐11 msec following a.c. stimulation. These i.p.s.p.s were similar to those evoked by lateral olfactory tract (l.o.t.) stimulation in their sensitivity to internally applied current and showed asymmetrical reversal during application of the hyperpolarizing current. 3. Volleys in the a.c. elicited e.p.s.p.s in type 1 g.c.l. cells whose characteristics were in agreement with those of inhibitory interneurones inferred from the analyses of mitral cell i.p.s.p.s. It has been suggested that these type 1 g.c.l. cells may be the common inhibitory interneurones (presumably granule cells) mediating both a.c.‐evoked and l.o.t.‐evoked i.p.s.p.s in mitral cells. 4. Conditioning a.c. stimulation depressed the test l.o.t.‐evoked i.p.s.p.s in mitral cells and test l.o.t.‐evoked e.p.s.p.s in type 1 g.c.l. cells. These observations are in good agreement with the hypothesis that l.o.t.‐evoked i.p.s.p.s are mainly mediated by the dendrodendritic reciprocal synapses between mitral cell dendrites and peripheral processes of granule cells. 5. The results are discussed in relation to the inhibitory mechanisms controlling mitral cell activity in the olfactory bulb.
The internodal axon membrane: electrical excitability and continuous conduction in segmental demyelination.
Authors: Bostock H , Sears T A
Published: December 2014

1. Longitudinal action currents were recorded from single undissected myelinated nerve fibres in intact, perfused ventral roots of normal rats and ones treated with diphtheria toxin to produce demyelination. 2. Closely spaced recording electrodes (120 micron), signal averaging and the use of a calibrating current throught the root permitted membrane currents to be determined over 240 micron lengths of nerve. Contour plotting was used to plot membrane current density as a function of space and time. 3. The previous result of Rasminsky & Sears (1972) of delayed saltation in demyelinated nerve fibres was confirmed. 4. In addition a new phenomenon of continuous conduction was observed, along distances of up to 1 1/2 times the afferent internodal distance. The continuous spatial distribution of inward current in these cases showed that electrical excitability was distributed along the internodes. 5. Internodal excitability was also revealed in demyelinated fibres by extra foci of inward current judged to be internodal on the basis of the spacing of the other (nodal) foci. 6. Continuous conduction occurred at velocities in the range of 1.1‐2.3 m/sec or roughly 1/20th‐1/40th of the velocities expected for normal stretches of the same fibres. 7. The continuous conduction was attributed to conduction along lengths of demyelinated axon. This was supported by estimates of 0.86 and 1.5 muF/cm2 for membrane capacity from the foot of a continuously conducted action potential. 8. The implications of internodal electrical excitability in demyelinated nerve fibres are discussed in relation to (a) recent estimates of the density of sodium channels in intact and homogenized normal nerves, (b) the pathophysiology of demyelinating disease.
Inactivation kinetics and steady‐state current noise in the anomalous rectifier of tunicate egg cell membranes.
Authors: Ohmori H
Published: December 2014

1. Inward K current through the anomalous rectifier in the tunicate egg (Halocynthis roretzi, Drashe) was studied under voltage clamp. The transient inward current in response to a step change of membrane potential was measured. The steady‐state current fluctuations were analysed using the power density spectrum (p.d.s.). 2. The inward current showed time‐dependent changes, which were described by a pair of the first order kinetic parameters, n and s for activation and inactivation, respectively. The steady‐state channel open probability due to the activation process (n infinity) was assumed to be 1.0 for V more negative than about‐‐100 mV, but that of the inactivation process (s infinity) and the time constant of inactivation (taus) were membrane potential dependent in the same potential range; both decreased with increasing hyperpolarization. 3. The inward currents in Na‐free choline medium did not inactivate, but were decreased in size. In Na‐free Li medium, inactivation was very small; the steady‐state conductance was not affected significantly. 4. After exposure to high Ca media, an increase of the conductance was observed. This effect is probably caused by an increase of intracellular Ca due to Ca ions entering through the Na channels. Mg ions slightly decreased the conductance. 5. In the hyperpolarized membrane (‐160 less than or equal to V less than or equal to ‐80mV), steady‐state current noise was recorded and analysed using p.d.s. A p.d.s. of the 1/[1 + (f/fc)2] type as well a p.d.s. of the 1/f type was observed; f, frequency, fc, cut‐off frequency. 6. fc was translated into time constant tauN (= 1/2pIfC) and compared with the time constant of inactivation, taus. There was a significant correlation betwen these values with a regression coefficient of 0.82. 7. Changing from 400 mM‐Li abloshied inactivation and changed the p.d.s. from the 1/[1 + (f/fc)2] into the 1/f type. These results (paragraphs 5‐‐7)suggest that the fluctuations in the steady‐state currents originatte in the inactivation gatin kinetics of the an ofthe anomalous rectifier. 8. The number of anomalous rectifier channels and the unit channel conductance were estimated from the 1/[1 + (f/fc)2] type current noise according to the formula : (see text), where I infinity = gamma Nninfinity s infinity (V‐‐VK), gamma the unit channel conductance, N the maximum number of channels that can be opened by a hyperpolarizing pulse per egg. The unit conductance was 6 pmho in standard artificial sea water and the channel density was 0.028/micrometer2. 9. The unit channel conductance (gamma) was dependent upon external K concentration, but the number ofchannels (N) was not. 10. The increase in chord conductance evoked by higher Ca concentrations was due to the increase of the channel number. By contrast, Mg ions seem to decrease the unit channel conductance slightly.