bluuebunny/crossref_metadata_2025 huggingface dataset:
The presence of ergothioneine in the central nervous system and its probable identity with the cerebellar factor
Authors: Crossland J. , Mitchell J. F. , Woodruff G. N.
Published: December 2014

1. Ergothioneine has been detected and quantitatively estimated in the brains of mice, rats, guinea‐pigs, rabbits, cats and sheep. It is present in the cerebellum in amounts ranging from about 3·0 μg/g in the cat to 10 μg/g in the guinea‐pig. Amounts in the cerebral hemispheres are much smaller, ranging from < 0·1 μg/g in the cat to 1·6 μg/g in the guinea‐pig.

2. Large amounts of ergothioneine (about 30 μg/g) were found in the optic nerves of the rabbit. None was detected in the dorsal columns of the spinal cord of the same species.

3. Ergothioneine has an excitatory action on the electrical activity of the cerebellum of the decerebrate rabbit and the excitatory actions of cerebellar extracts on this preparation are completely accounted for by their contained ergothioneine.

4. It is concluded that the cerebellar factor of Crossland & Mitchell (1956) is identical with ergothioneine.
The inhibitory innervation of the taenia of the guinea‐pig caecum
Authors: Burnstock G. , Campbell G. , Rand M. J.
Published: December 2014

1. The inhibitory innervation of the taenia of the guinea‐pig caecum has been studied, after blocking the responses to stimulation of excitatory cholinergic nerves with atropine.

2. Stimulation of the perivascular nerves supplying the taenia caused relaxations. These nerves had properties which were typical of sympathetic post‐ganglionic adrenergic nerves. The relaxations caused by stimulation were maximal at frequencies of stimulation above 30 pulses/sec and they were abolished by bretylium, guanethidine and 1,1‐dimethyl‐4‐phenylpiperazinium iodide (DMPP).

3. The taenia is also innervated by intramural inhibitory nerves with their cell bodies in Auerbach's plexus. These nerves can be excited by electrical stimulation of the taenia or by the application of ganglion‐stimulating drugs.

4. The intramural inhibitory nerves have different properties from sympathetic adrenergic nerves. Relaxations in response to stimulation were maximal with frequencies of stimulation of about 5 pulses/sec and they were not blocked by bretylium, guanethidine or DMPP.

5. Preganglionic cholinergic fibres in the caecal wall make synaptic connexions with the intramural inhibitory neurones.

6. The role of the intramural inhibitory neurones in intestinal activity and their possible connexions with the central nervous system have been discussed.
Influence of temperature acclimatization on sodium—glucose interactions in the goldfish intestine
Authors: Smith M. W.
Published: December 2014

1. Transmural potentials across goldfish intestines in vitro were found to depend on the acclimatization temperature of the fish. At any incubation temperature potentials were lower in fish kept previously at a high temperature, and if the transmural potentials were recorded at incubation temperatures equal to the previous acclimatization temperatures the values remained constant from 8 to 30° C. The glucose‐evoked potential was also reduced by previous acclimatization of the fish to a high temperature.

2. As the sodium concentration was reduced the steady transmural potential increased and later fell in proportion to the low external sodium concentration, but the glucose‐evoked potential fell as soon as the sodium concentration was reduced below 140 m
M. Similar changes were seen with intestines taken from fish acclimatized to a high temperature but both the steady‐state potential and the transitory glucose‐evoked potential were more dependent on the external sodium concentration.

3. The maximum glucose‐evoked potential depended on the concentration of glucose used and temperature acclimatization had no significant effect on this relation. The steady potential was lower in the presence of glucose at low incubation temperatures but higher at higher incubation temperatures, and the temperature at which glucose ceased to inhibit depended on the previous acclimatization temperature. Glucose also lowered the steady potential, whatever the previous acclimatization temperature, when the external sodium concentration was low.

4. The inhibitory effect of glucose on the steady potential of an intestine taken from a 30°‐acclimatized fish could be abolished by lowering the external concentration of glucose from 27 to 16 m
M.

5. Intestines taken from fish acclimatized to 3° C gave variable results.

6. It is concluded that sodium moves across the luminal membrane of the goldfish mucosa attached to a carrier which can exist in one of two forms. It is changes in this postulated carrier which serve to stabilize sodium transport at different acclimatization temperatures. Changes in the concentration of this postulated carrier may also occur and function in the regulation of sodium transport, particularly at acclimatization temperatures below 15° C, where the switching of the carrier does not operate.
A study of the interaction between motoneurones in the frog spinal cord
Authors: Grinnell A. D.
Published: December 2014

1. A short‐latency interaction between motoneurones has been studied with intracellular and root potential recordings from the isolated spinal cord of the frog. Antidromic stimulation of one ventral root causes brief depolarization (VR‐EPSP) of the motoneurones of adjacent, non‐excited motoneurones. The summed activity of many such VR‐EPSPs can be seen as a brief depolarization (VR‐VRP) passing out an adjacent ventral root.

2. Both intracellular and root‐recorded signs of this interaction are graded in amplitude.

3. It was found that this interaction decreased with increasing temperature. This is in contrast to the behaviour of the ventral root potential resulting from dorsal root stimulation (DR‐VRP) or the dorsal root potentials resulting from either dorsal root (DR‐DRP) or ventral root (VR‐DRP) stimulation, all of which increased in amplitude from below 10 to about 17° C.

4. Pharmacological evidence suggests that the interaction between motoneurones is not chemically mediated. The VR‐VRP was not affected by a large variety of transmitter blocking agents, including curare, dihydro‐β‐erythroidine, atropine, succinylcholine, hexamethonium and DOPA, while the VR‐DRP, which probably originates with the release of ACh from an axon collateral, was consistently blocked.

5. Mg2+ suppressed the VR‐VRP more slowly than the other potentials, and this suppression was increased by adding Ca2+, rather than reversed, as in the case of the other root potentials, which are presumably mediated by chemical transmission.

6. The interaction between motoneurones is strongly facilitated by orthodromic depolarization of the motoneurones being antidromically stimulated. Extracellular recordings within the cord support the conclusion that this facilitation is a result of the enhancement of antidromic invasion, perhaps especially of the dendrites, by slight depolarization.

7. One VR‐VRP (or VR‐EPSP) first suppresses response to another (for about 10 msec), then facilitates response to the second, with maximum effect around 20‐40 msec. This is the case whether both stimuli go to the same or to different ventral roots, although occlusion is less and facilitation greater in the latter case. Occlusion of the VR‐EPSP also results from full excitation of the cell in which recording is being done.

8. The mechanism of this interaction remains uncertain, but it would seem likely that overlapping dendrites of adjacent motoneurones interact with each other electrically through close apposition or specialized contacts. Occlusion would result from the refractoriness of strongly depolarized dendrites, facilitation from the enhancement of invasion of antidromically stimulated motoneurones by the weaker (or residual) depolarization occurring after earlier activity of motoneurones or their dendrites.
The effect of acute haemorrhage in the dog and man on plasma‐renin concentration
Authors: Brown J. J. , Davies D. L. , Lever A. F. , Robertson J. I. S. , Verniory A.
Published: December 2014

1. The effect of acute haemorrhage on the plasma renin concentration was studied in the dog and man.

2. Plasma‐renin concentration was regularly increased after the larger bleeds; after the smaller haemorrhages plasma‐renin concentration remained unchanged.

3. The results are discussed in relation to current hypotheses concerning the control of renin and aldosterone secretion.
Somatic sensory cortical projection areas excited by tactile stimulation of the cat: a triple representation
Authors: Darian-Smith I. , Isbister J. , Mok H. , Yokota T.
Published: December 2014

1. The specific somatic sensory projection from the face to the cerebral cortex of the cat was investigated in two series of experiments. α‐chloralose and Nembutal were the anaesthetics used.

2. Evoked potentials, recorded at the cortical surface, were used in the first series for identifying three discrete projection areas from the face and forelimb. Two of these regions correspond to the established S I and S II projections. The third area, designated S III, was in the dorsal part of the anterior suprasylvian gyrus adjacent to the ansate sulcus.

3. Single neurone analysis demonstrated that the cell populations responding to ‘tactile’ cutaneous stimulation of the face within each of the three specific somatic sensory projection areas had similar static functional properties. Most neurones observed had receptive fields restricted in size and were modality specific. Their receptive fields were mainly contralateral, although some had an ipsilateral extension. Fewer than 10% of cells observed in each specific cortical area were ‘non‐specific’. Such cells had extensive receptive fields and some of these fired to an auditory stimulus.

4. Both field recording and single neurone analysis revealed a somatotopic projection to the S III area as well as to the S I and S II areas.
The behaviour of a mammalian muscle during sinusoidal stretching
Authors: Rack P. M. H.
Published: December 2014

1. Tension changes have been recorded in tetanized and passive cat soleus muscles during sinusoidal stretching at frequencies between 0·25 and 12·5 c/s.

2. During sinusoidal stretching the muscle tension varied in an approximately sinusoidal manner. The tension record showed an angular advance on muscle length. A method of measuring mean angular advance in nonlinear systems is described.

3. In tetanized muscle, resistance to lengthening increased with increasing frequency of stretching. With increasing frequency the elastic stiffness increased more rapidly than the viscous stiffness, so that at the higher frequencies the angular separation between length and tension became smaller.

4. With increasing stretch amplitude the elastic stiffness of the tetanized muscle declined, and the mean angular advance of tension became larger.

5. In passive muscle the viscous stiffness increased at the higher frequencies, and the mean angular advance of tension on length was correspondingly increased.

6. The functional significance of these findings and their relation to the findings of other workers are discussed.
The effect of membrane fixed charges on diffusion potentials and streaming potentials
Authors: Diamond Jared M. , Harrison S. C.
Published: December 2014

1. Electrical potential differences (p.d.'s) have been measured across an in vitro preparation of rabbit gall‐bladder.

2. When the gall‐bladder separates identical bathing solutions, the p.d. is always zero, regardless of the composition of the bathing solution. Hence the gall‐bladder is symmetrical: i.e. the mucosal and serosal cell membranes have the same relative permeability coefficients.

3. Osmotic water flow causes streaming potentials of up to 20 mV, of a sign indicating greater permeability to cations than to anions.

4. At constant osmolarity, streaming potentials increase slightly with NaCl concentration. Streaming potentials decrease considerably with changes in osmolarity resulting from changes in NaCl concentration.

5. Diffusion potentials resulting from electrolyte concentration gradients are fitted well by the constant‐field equation with the relative permeability coefficients PNa = 1·00, PCl = 0·33, PK = 2·3. These permeability coefficients are independent of osmolarity and of salt concentration.

6. Relative to 0·25 m
M‐Ca, 5 m
M‐Ca reduces streaming potentials by 40%, NaCl diffusion potentials by 62%, and potassium diffusion potentials by 43%.

7. The aqueous channels through which water and electrolytes traverse the cell membranes of the gall‐bladder contain negative fixed charges, which are blocked by Ca. The physiological significance of the charges may be to reduce chloride permeability and thereby to increase the effectiveness of the gall‐bladder in concentrating bile.

8. The effect of pH, and analogy with surface charges of other cells, suggest that the charges are organic acids of low pKa.
Non‐linear osmosis
Authors: Diamond Jared M.
Published: December 2014

1. The relation between osmotic gradient and rate of osmotic water flow has been measured in rabbit gall‐bladder by a gravimetric procedure and by a rapid method based on streaming potentials. Streaming potentials were directly proportional to gravimetrically measured water fluxes.

2. As in many other tissues, water flow was found to vary with gradient in a markedly non‐linear fashion. There was no consistent relation between the water permeability and either the direction or the rate of water flow.

3. Water flow in response to a given gradient decreased at higher osmolarities. The resistance to water flow increased linearly with osmolarity over the range 186‐825 m‐os
M.

4. The resistance to water flow was the same when the gall‐bladder separated any two bathing solutions with the same average osmolarity, regardless of the magnitude of the gradient. In other words, the rate of water flow is given by the expression (Om — Os)/[Ro′ + ½k′ (Om + Os)], where Ro′ and k′ are constants and Om and Os are the bathing solution osmolarities.

5. Of the theories advanced to explain non‐linear osmosis in other tissues, flow‐induced membrane deformations, unstirred layers, asymmetrical series‐membrane effects, and non‐osmotic effects of solutes could not explain the results. However, experimental measurements of water permeability as a function of osmolarity permitted quantitative reconstruction of the observed water flow—osmotic gradient curves. Hence non‐linear osmosis in rabbit gall‐bladder is due to a decrease in water permeability with increasing osmolarity.

6. The results suggest that aqueous channels in the cell membrane behave as osmometers, shrinking in concentrated solutions of impermeant molecules and thereby increasing membrane resistance to water flow. A mathematical formulation of such a membrane structure is offered.
Increased permeability of the capillaries of the rat heart to the plasma albumin with asphyxiation and with perfusion
Authors: Sutherland T. M. , Young D. A. B.
Published: December 2014

1. Studies on the rate of efflux from the isolated perfused rat heart of plasma albumin conjugated with Evans Blue showed the conjugate to have penetrated extensively the extravascular compartment of the organ during a period of 2 min. This was confirmed by direct analysis of hearts for Evans Blue after perfusion.

2. Exposure of the hearts to Evans Blue‐albumin conjugate for 8 min in vivo showed no significant penetration of the interstitial space.

3. With the isolated preparation inclusion of promethazine in the perfusing medium significantly diminished the rate of penetration of the extravascular compartment by the conjugate as did injection of the animals with either reserpine 2 days before, or bretylium immediately before the experiment.

4. Penetration of the interstitial compartment in vivo could be induced by repeated asphyxiation. This penetration could also be diminished by promethazine but was not influenced by mepyramine maleate.

The increased permeability of capillaries to plasma proteins can be readily demonstrated in the whole animal by detecting the leakage from the vasculature of the plasma proteins conjugated with a dye (Menkin & Menkin, 1930; Miles & Miles, 1952). Evans Blue, which has been widely used as a vascular marker because of the stability of its conjugate with plasma albumin, is the most suitable dye for this purpose. In the present work this method has been applied to the isolated rat heart, to determine if changes in capillary permeability occur in the perfused tissue.

When plasma albumin conjugated with Evans Blue was used as a vascular marker in this preparation, its rate of clearance was very much less than that of erythrocytes, and the amount contained in the heart corresponded to a space approaching that occupied by extracellular markers such as raffinose and inulin. It was concluded, therefore, that there was a failure of a considerable number of the cardiac capillaries to retain the plasma albumin, and subsequent work was directed towards the identification of the condition that gives rise to these changes and the possible involvement of a permeability factor.

A preliminary account of part of this work was given to the Physiologcal Society (Sutherland & Young, 1961).
Taste reception in the goat, sheep and calf
Authors: Bell F. R. , Kitchell R. L.
Published: December 2014

1. The goat, sheep and calf have gustatory chemoreceptors which respond to salt, sweet, sour and bitter solutions, from which the afferent fibres pass centrally in the chorda tympani and glossopharyngeal nerves.

2. Action potentials in the afferent gustatory nerves can also be detected when the tongue is irrigated with sodium bicarbonate, ethylene glycol, glycerine, and saccharine.

3. Distilled water reduces the background activity in the isolated gustatory nerves, thus demonstrating the absence of fibres in ruminant ungulates of receptors which respond to stimulation by distilled water.

4. The responses from the chemoreceptors, associated especially with the circumvallate papillae, are enhanced if the papillae are gently moved at the time of irrigation with sapid solutions.

5. The chorda tympani is most responsive to salt and acid solutions while the glossopharyngeal is more responsive to sugars, quinine and acid.
The formation of peptides with uterine activity from ovine, human and bovine growth hormones and from bovine and ovine lactogenic hormones
Authors: Lockett Mary F.
Published: December 2014

1. Both starch gel and disk electrophoresis demonstrated stepwise degradation of acidic preparations of human and bovine growth hormones and of ovine and bovine lactogenic hormones in solution at pH 9·0‐10·0. This developed in 1‐3 weeks in refrigerated solutions and in 5‐16 hr on incubation at 37° C. Increasing acidity accompanied degradation.

2. Oxytocic activity, initially absent, developed in these same solutions of hormones during stepwise degradation and appeared to be associated with a single phase of degradation.

3. Storage in solution at pH 9·5 generated oxytocic activity in an initially basic preparation of ovine growth hormone. The uterine action was attributable to a small amount of acidic material with electrophoretic properties very similar to those of the oxytocic fractions formed during stepwise degradation of the acidic preparations of growth and lactogenic hormones.

4. Prolonged storage of all these hormones at pH 9·0‐10·0 resulted in the formation of acidic substances of low molecular weight which ran close to the buffer front and were dialysable (14 hr) through membranes which permitted the passage of nonapeptides in 6‐8 hr.

5. α‐Chymotrypsin very rapidly generated uterine stimulant action in freshly prepared solutions of human growth and bovine lactogenic hormones at pH 9·5.

6. All the hormone samples used proved capable of hydrolysing purified ox haemoglobin, urea‐denatured, at pH 9·5.
Rapid hydrogen ion uptake of rod outer segments and rhodopsin solutions on illumination
Authors: Falk G. , Fatt P.
Published: December 2014

1. Flash illumination of a suspension of frog rod outer segments or rhodopsin solution in contact with a platinum electrode produces a rapidly developing negative displacement of potential of the electrode (with respect to a reversible electrode).

2. The amplitude of the potential change varies inversely with the H+ buffering capacity of the medium. It is inferred that the response is due to an uptake of H+ by the rod outer segments or rhodopsin, with the platinum surface acting as a pH electrode.

3. Determination of the action spectrum shows that the response depends on the absorption of light by rhodopsin.

4. In frog rods one acid‐binding group with a pK of about 7·9 is produced for each molecule of rhodopsin bleached, consistent with a rhodopsin concentration in frog rods of 1·7 m
M.

5. It is suggested that the time course of the response with rhodopsin solutions reflects the kinetics of the conversion of metarhodopsin I to metarhodopsin II.

6. A slower time course of voltage change observed for suspensions of outer segments is attributable to the time required for the diffusion of H+ buffer out of the rods.
Anomalous rectification in the metacerebral giant cells and its consequences for synaptic transmission
Authors: Kandel E. R. , Tauc L.
Published: December 2014

1. In the central neurones that have so far been examined the passive electrical properties of the extrasynaptic membrane has been shown to be relatively constant in the subthreshold range. Consequently, excitatory synaptic potentials produced by chemical transmission tend to vary in amplitude with changes in membrane potential, decreasing with depolarization and increasing with hyperpolarization.

2. In the two symmetrical giant cells of the ventral metacerebrum of the snail, the EPSPs failed to show the expected alterations in amplitude with changes in membrane potential. Near the resting level the EPSP increased slightly with membrane depolarization and decreased slightly with hyperpolarization.

3. These paradoxical results were not attributable to a change in transmitter release since similar results were obtained when ACh, the putative transmitter, was released iontophoretically on to the cell membrane by means of an extracellular pipette.

4. Measurement of the current—voltage relation of the extrasynaptic membrane revealed two types of rectifying conductance changes. The first, an increase in conductance with depolarization, was turned on at a depolarization of about 15 mV. Its conductance change was similar to the delayed rectification familiar from studies of peripheral nerve and muscle. The second occurred on either side of the resting level, from about 15 mV hyperpolarization to about 10 mV depolarization, and manifested itself as a decrease in conductance with depolarization and an increase with hyperpolarization. By analogy to a similar phenomenon known to occur in skeletal muscle this second rectification has been termed anomalous rectification.

5. The average resistance at 25 mV hyperpolarization was 2·3 × 106 Ω, while at 10 mV depolarization it was 2·1 × 107 Ω, yielding an average rectification ratio of 10 for the anomalous conductance change.

6. The anomalous rectifying conductance seems to account for the paradoxical behaviour of the EPSP and ACh response to changes in membrane potential. Moreover, the finding that the sharpest change in the anomalous rectification curve occurred on either side of the resting level suggests that this rectification is functionally important as a postsynaptic determinant of synaptic efficacy. Several additional lines of evidence in support of this suggestion have been obtained.
The composition of human saliva secreted in response to a gustatory stimulus and to pilocarpine
Authors: Dawes C.
Published: December 2014

1. The composition of human saliva secreted in response to sour lemon drops (
S.L.D.), and pilocarpine, was studied.

2. At a given flow rate, pilocarpine‐stimulated submandibular and parotid saliva contained less sodium and potassium and an equivalent amount of inorganic phosphate, and parotid saliva also contained more calcium and protein than did the corresponding types of
S.L.D.‐stimulated saliva.

3. Prolonged
S.L.D. stimulation did not cause a depletion in the protein concentration of either parotid or submandibular saliva and neither this procedure nor pilocarpine stimulation altered the proportions of the different proteins secreted.

4. Pilocarpine was judged to be an inadequate substitute for more physiological, gustatory stimuli.
The effect of inhibitors on intestinal transfer of glucose and fluid
Authors: Detheridge Joan F. , Matthews J. , Smyth D. H.
Published: December 2014

1. The effect of various experimental conditions has been studied on the transfer of hexoses and fluid by everted sacs of rat small intestine.

2. The existence of glucose‐dependent and glucose‐independent mechanisms has been confirmed; the energy for the former comes from the citric acid cycle, and for the latter from either the glycolytic or pentose cycle.

3. The energy for glucose transfer against a concentration gradient can come from metabolism of glucose by some route other than the citric acid cycle, or it may come from the citric acid cycle.

4. Two‐stage transfer of glucose is discussed as a possible explanation of the results.
A study of the inhibitory action of γ‐aminobutyric acid on neuromuscular transmission in the crayfish
Authors: Takeuchi A. , Takeuchi Noriko
Published: December 2014

1. The effect of γ‐aminobutyric acid (GABA) on the neuromuscular junction of the crayfish (Cambarus clarkii) was investigated. The drug was applied iontophoretically to a junction and the potential changes were recorded intracellularly as well as extracellularly with micro‐electrodes.

2. The amplitude of the potential produced by iontophoretically applied
L‐glutamate was decreased by simultaneous application of GABA to the same junctional area. When the membrane potential was clamped at the resting level the clamping current for the
L‐glutamate injection was not changed by GABA application, indicating that there is no appreciable competition between
L‐glutamate and GABA for the glutamate‐sensitive receptor.

3. The excitatory nerve was stimulated repetitively and the excitatory junctional potentials (e.j.p.s) were recorded extracellularly with a micro‐electrode placed on the surface of the muscle. The average size of the extracellular e.j.p.s was reduced by the application of GABA.

4. The number of quanta released per impulse calculated from the extracellular e.j.p.s was decreased during the application of GABA, while the quantum size remained unchanged.

5. The size of the excitatory presynaptic nerve spike was decreased by the application of GABA. However, no appreciable change was observed in the inhibitory nerve spike.

6. These results indicate that in addition to its post‐synaptic action GABA acts on the excitatory presynaptic nerve terminal and reduces the release of the transmitter.
On the permeability of the presynaptic terminal of the crayfish neuromuscular junction during synaptic inhibition and the action of γ‐aminobutyric acid
Authors: Takeuchi A. , Takeuchi Noriko
Published: December 2014

1. The contribution of chloride to presynaptic inhibition of the crayfish neuromuscular junction during the action of γ‐aminobutyric acid (GABA) and the inhibitory transmitter was investigated. Chloride in van Harreveld's solution was replaced with propionate, acetate, methylsulphate or glycerophosphate and electrical changes were recorded intracellularly and extracellularly with micro‐electrodes.

2. When the preparation was soaked in Cl‐deficient solutions, the quantum content of the excitatory junctional potentials (e.j.p.s), calculated from the number of failures, was increased.

3. The presynaptic inhibitory action of GABA was reduced or almost absent when the preparation was soaked in Cl‐deficient solution. In Cl‐deficient solution the stimulation of the inhibitory axon showed little or no inhibitory action on e.j.p.s.

4. If GABA was applied shortly after the outside solution was changed to the Cl‐deficient one, the frequency of the spontaneous e.j.p.s was increased transiently.

5. It is suggested that GABA or the inhibitory transmitter act on the presynaptic excitatory terminal and predominantly increase its permeability to chloride.
Electrical responses of smooth muscle to external stimulation in hypertonic solution
Authors: Tomita T.
Published: December 2014

1. The electrical responses of single smooth muscle cells of the guinea‐pig taenia coli to external stimulation were studied in two times hypertonic solution and compared with the responses to intracellular stimulation.

2. Exposure to Krebs solution made two times hypertonic by adding sucrose abolished the mechanical movement and stopped the spontaneous electrical activity. The electrical response to stimulation was essentially similar to that in physiological solution.

3. When the tissue was placed between stimulating electrodes, the cells near the cathode were depolarized and produced spikes, while the cells near the anode were hyperpolarized and produced small spikes only with weak stimuli. The cells near the centre were not polarized but produced spikes with a frequency pattern similar to that near the cathode.

4. When both stimulating electrodes were put close together at one end of the tissue, the intracellularly recorded extrapolar polarization changed its polarity at 1–2 mm distance from the stimulating electrode. When an insulating partition was placed between the stimulating and recording site, the reversed polarity was no longer observed and the electrotonic potential spread decayed roughly exponentially with distance from the stimulating electrode. The time course of the electrotonic potential was similar to that predicted from the cable equation applied to nerve. The space constant was 1·68 ± 0·08 mm (
S.E. of mean) and the time constant was 60‐100 msec. The cable properties may be explained by assuming that many fibres, connected in series and in parallel, are aggregated as functional units.

5. The strength—duration curve was a simple hyperbola and the chronaxie was about 20 msec. The relation between extracellularly applied current and intracellularly recorded potential showed that membrane resistance decreased with depolarization and slightly increased with hyperpolarization. The spike was propagated in both directions at the same speed as in physiological solution (7·3 ± 0·7 cm/sec).

6. Long anodal current often produced electrical activity of low amplitude which seemed to be due to the spike activity near the cathode, because the same frequency modulation was seen in both activities, and external hyperpolarization reduced the size of the propagated spike. Cessation of a strong and long anodal current was followed by slow depolarization, about 1 sec in duration and up to 10 mV in amplitude, which sometimes triggered a spike.

7. The difference between responses to intracellular and to external stimulation may be explained by assuming that different parts of the cell membrane have different electrical properties. They may be: A, areas of close apposition between cells; B, areas capable of generating the slow component; C, an area capable of producing the spike, but less excitable.
The flicker fusion frequency of the blue‐sensitive mechanism of colour vision
Authors: Brindley G. S. , Du Croz J. J. , Rushton W. A. H.
Published: December 2014

1. The flicker fusion frequency for blue stimuli on zero background increases steadily with increasing luminance up to 50 c/s, but if a strong yellow background is added it increases steadily only to about 18 c/s, and then remains nearly independent of luminance over a range of a factor of 20.

2. It is argued that the maximum flicker fusion frequency is about three times lower for the blue‐sensitive mechanism of colour vision than for the red‐ or green‐sensitive.
The thalamic relay and cortical projection of Group I muscle afferents from the forelimb of the cat
Authors: Andersson S. A. , Landgren S. , Wolsk D.
Published: December 2014

1. Stimulation of Group I muscle afferents in contralateral forelimb nerves evoked a response in nucleus ventralis posterolateralis (VPL) in the thalamus of the cat. This response was located in the rostral two‐thirds of VPL in a narrow zone near the dorsomedial border of the nucleus.

2. Group I afferents in nerves from more than one of the muscles in the contralateral forelimb often excited the same thalamic relay cell. In addition these cells were often discharged by skin afferents from the contralateral forelimb. They were not affected by electrical stimulation of the dorsal column‐lemniscal or the spino‐cervico‐lemniscal paths from the contralateral hind limb.

3. In experiments with peripheral conduction paths of similar length, the latency of the thalamic focal potential evoked by stimulation of Group I muscle afferents in the nerve to m. extensor carpi radialis was 3·8
S.E. ± 0·1 msec, and that of the focal potential evoked by skin afferents (n. radialis superficialis) in the centromedial part of VPL was 4·3 ± 0·1 msec.

4. The majority of the thalamic neurones discharged by Group I muscle afferents responded with a latency shorter than 1 msec to electrical stimulation of the cerebral cortex in the region of the post‐cruciate dimple. A considerable number of the thalamic Group I relay cells were also discharged with a similar short latency from another cortical focus located on either side of the anterior suprasylvian sulcus near the S II hind limb areas. These responses were considered to be antidromic in nature, and the findings were interpreted as indicating two separate cortical projection areas for the Group I path. The second projection area was assumed to be located in the cortical fold formed by the anterior suprasylvian sulcus.

5. Cortical stimulation also excited the thalamic Group I relay cells trans‐synaptically. Trans‐synaptic excitation with short (1‐2 msec) and longer (2‐7 msec) latency was observed. The cortical focus near the S II area was particularly potent in evoking trans‐synaptic excitation in the thalamic region where the Group I relays were located.
Analysis of sodium and potassium conductances in the procaine end‐plate potential
Authors: Maeno Takashi
Published: December 2014

1. The effect of procaine on neuromuscular transmission was studied on the sartorius muscle of the frog, Rana pipiens, with intracellular microelectrodes.

2. Mean quantal content of the e.p.p. in high Mg Ringer was little affected by procaine.

3. The short circuit effect of the e.p.p. on the action potential, which was an indication of change in potassium conductance (ΔgK) during the e.p.p., was investigated on the muscle fibre immobilized in hypertonic Ringer. It was found that procaine had little effect on ΔgK.

4. The equilibrium potential of the e.p.p. (Ee.p.p.) was measured in hypertonic Ringer. Ee.p.p. was 12 mV in control experiment and was decreased to 3·1 mV in 10−4 procaine. The ratio ΔgNa/ΔgK was calculated to be 2·75 in control and 2·11 in 10−4 procaine.

5. E.p.p.s were recorded extracellularly to study changes in the time course of ΔgNa in procaine. Procaine reduced the peak magnitude of ΔgNa; following the peak, ΔgNa fell quickly to a lower level, which decayed much more slowly.

6. An end‐plate model with separate sodium and potassium pathways is proposed to explain the procaine e.p.p. Procaine is assumed to affect the time course of ΔgNa.

7. E.p.p.s simulated from the proposed end‐plate model with theoretical ΔgNa and ΔgK agreed satisfactorily with actual procaine e.p.p.
Circulatory responses to simulated gravitational shifts of blood in man induced by exposure of the body below the iliac crests to sub‐atmospheric pressure
Authors: Brown Ellen , Goei J. S. , Greenfield A. D. M. , Plassaras G. C.
Published: December 2014

1. Exposure of the body from iliac crests to feet of a horizontal subject to a pressure 70 mm Hg below atmospheric causes a displacement of about 10 g of blood/kg total body weight from the upper to the lower part of the body. Much of this blood is returned very rapidly at the end of suction.

2. During suction, the changes in the circulation resemble those during a foot‐down tilt. After suction, the changes resemble to some extent those following the Valsalva manoeuvre.

3. The overshoot of forearm blood flow following suction is caused by variations in the activity of adrenergic vasoconstrictor nerves. The receptors for this reflex have not been identified, but their stimulation depends upon a rapid and large return of blood to the central circulation.
Application of the sucrose‐gap method to determine the ionic basis of the membrane potential of smooth muscle
Authors: Bennett M. R. , Burnstock G.
Published: December 2014

1. A study has been made of the ionic basis of the smooth muscle membrane potential by changing the ionic environment of the ureter and recording the resultant potential changes with the sucrose gap. The relation of these potential changes to the membrane potential of individual cells has also been studied.

2. It is shown that if the ionic environment of all the cells in the tissue is uniformly changed, then the potential change recorded by the sucrose gap is proportional to the magnitude of the short circuit factor, the liquid junction potential change at the sucrose‐test solution interface, and the amplitude of the membrane potential change of a single cell.

3. A simple method is described for determining the steady value of the short circuiting factor, and the liquid junction potential changes, so that the recorded potentials can be corrected to give membrane potentials.

4. The action of isotonic potassium sulphate and isotonic potassium chloride on the membrane potentials of the ureter smooth muscle cells is described.

5. When the extracellular potassium concentration is changed reciprocally with the extracellular chloride concentration in order to maintain these ions in a Donnan equilibrium across the muscle cell membrane, the membrane potential is found to decrease by 53 mV for a 10‐fold change in external potassium concentration, for concentrations above 10 m
M.

6. It is concluded that above an external potassium concentration of 10 m
M the membrane potential of ureteral smooth muscle cells obeys the prediction of the Nernst equation for a potassium electrode.
Central pathways of some autonomic reflex discharges
Authors: Coote J. H. , Downman C. B. B.
Published: December 2014

1. Electrical stimulation of spinal sensory nerves evoked discharges in inferior cardiac and renal nerves. In the anaesthetized cat both an early and a late response could be recorded in each nerve.

2. For any one afferent input the central delay of the late cardiac nerve response was significantly less than that of the late renal nerve response. The central delay of the early responses was similar for both nerves. In the spinal cat only the early response was present.

3. Cooling the floor of the 4th ventricle abolished the late responses in renal nerves, but left reflex volleys in white rami and intercostal nerves unchanged.

4. Stimulation in the brain stem evoked responses in both cardiac and renal nerves which had a shorter latency than the reflexes evoked in these nerves by stimulating dorsal roots.

5. The late responses could be abolished by lesions in the cervical spinal cord.

6. Such evidence led to the conclusion that there are two pathways for reflex discharge into inferior cardiac and renal nerves, one involving a supraspinal relay and the other confined to the spinal cord.
An inhibitory process in the cerebral cortex
Authors: Krnjević K. , Randić Mirjana , Straughan D. W.
Published: December 2014

1. In cats, rabbits and monkeys, single cortical shocks can reduce the excitability of cortical neurones for 100‐300 msec; the inhibitory effect is readily demonstrated, even in previously quiescent cells, against a background of activity evoked with small amounts of
L‐glutamate, released from an extracellular recording micropipette by iontophoresis.

2. Other forms of cortical activity are also inhibited in a similar way by direct or indirect cortical stimulation; they include single unit discharges produced by iontophoretic applications of ACh or by a cathodal current, spontaneous discharges, and slow wave activity, both spontaneous and evoked.

3. Most stimuli which elicit cortical activity also evoke some inhibition in the cortex, for instance, transcallosal volleys, and thalamic or peripheral shocks. In each case, a characteristic, prolonged depression is produced by single shocks.

4. The most effective stimuli are direct cortical shocks, especially when applied within the cortex, below a depth of 0·6 mm; surface cathodal shocks are more effective than anodal shocks. These stimuli do not first excite the cells which are inhibited and they are not strong enough to cause appreciable local injury.

5. Because of its long duration, the inhibition is often readily maintained by repetitive stimulation at frequencies of 5‐7/sec. A cumulative effect leads to a further silent period after the end of stimulation; this increases with the strength, frequency and duration of the tetanus, so that after stimulation at 50‐100/sec, the silent period may last for over 1 min. During this time, a stronger depolarizing stimulus can initiate firing.

6. The inhibitory effect is often preceded and followed by phases of increased excitability; these may also show cumulative enhancement during repetitive stimulation, and a high frequency tetanus often leads to a short after‐discharge, which is then followed by a long silent period, as above. Comparable changes take place in rabbits during spreading depression.

7. The inhibitory effect of a direct shock can spread over an area covering 1 cm of cortical surface, affecting the cells through all cortical layers; but the spread is uneven in different directions, being particularly poor under most sulci.

8. This type of inhibition can be elicited in all areas of the neocortex, and it is evident in kittens within a week of birth.

9. Antidromic pyramidal stimulation is very much less effective in evoking inhibition of Betz cells, and other cortical neurones, than direct cortical stimulation; the inhibition by direct shocks is therefore not likely to be mediated through pyramidal excitation.
Nature of a cortical inhibitory process
Authors: Krnjević K. , Randić Mirjana , Straughan D. W.
Published: December 2014

1. Since the inhibitory effect of direct or indirect cortical stimulation on cortical units can be overcome by excitation with even more
L‐glutamate, it is not likely to be due to an excessive depolarization.

2. Further evidence that surface stimulation has a hyperpolarizing action on cortical cells was obtained by intracellular recording from over 120 pericruciate cells. Inhibitory post‐synaptic potentials (IPSPs) are seen in most cells, which are comparable in threshold and duration with the inhibitory effect observed extracellularly. The IPSPs are usually not preceded by a discharge of the same cells.

3. The extracellular slow wave corresponding to the inhibitory effect varies considerably with different preparations and different depths within the cortex. A predominantly positive wave is only seen occasionally. In general, the relevant wave recorded deep in the cortex tends to be mainly negative.

4. This negative slow wave can be much potentiated by tetanic stimulation, or, especially, by a large local release of
L‐glutamate; the last procedure is most effective either very near the surface, or below a depth of 1·0 mm. These observations suggest that inhibitory synapses occur more profusely in the superficial half of the grey matter.

5. Unlike
L‐glutamate, GABA tends to depress the ‘inhibitory’ slow wave.

6. The inhibitory effect must be produced by intracortical neurones, since it is fully preserved in isolated cortical slabs. In both acute and chronic slabs, the inhibition is particularly well marked and long lasting, partly because spontaneous activity and the usual post‐inhibitory rebound of excitability are absent.

7. The intracortical pathways responsible for the spread of inhibition cannot be situated mainly in the superficial layers, as they are not readily blocked by surface cooling or the application of local anaesthetics.

8. One can record unit discharges immediately after a surface shock. Some of these discharges could be from inhibitory interneurones, but they do not last more than 10‐20 msec.

9. We conclude from the observations described in this and a previous paper (Krnjević, Randić & Straughan, 1966a) that a widespread system of intracortical interneurones can be activated by direct or indirect stimulation of the cortex; these interneurones have a powerful and prolonged inhibitory action on most cortical cells.

10. The identity and distribution of the postulated inhibitory interneurones is discussed in the light of some relevant morphological evidence.
Membrane potential and ion content in the smooth muscle of the guinea‐pig's taenia coli at different external potassium concentrations
Authors: Casteels R. , Kuriyama H.
Published: December 2014

1. The relation between the membrane potential and the intracellular ion concentration of the taenia coli was studied in solutions with different external potassium concentrations.

2. Isotonic solution in which the sum of NaCl+KCl was constant did not produce swelling of the smooth muscle of taenia coli, even at high [K]o, and did not change the intracellular chloride concentration.

3. Addition of an equivalent amount (118 m
M) of NaCl or KCl to Krebs solution produced the same loss of water.

4. Solutions in which the product [K][Cl] was kept constant decreased the internal chloride concentration so that the chloride equilibrium potential became temporarily positive and returned only after 2 hr to a negative value.

5. From these results and the finding that even in normal Krebs solution ECl was about 35 mV more positive than the membrane potential, it is concluded that the chloride ions are not passively distributed. The potassium equilibrium potential is the main factor in the generation of the membrane potential. The large discrepancy between the two can be explained by the non‐passive chloride distribution and by the sodium permeability of the membrane. The maintenance of the normal cell volume in solutions with constant sum of NaCl+KCl is explained by the constant intracellular chloride concentration.
Tension development in highly stretched vertebrate muscle fibres
Authors: Gordon A. M. , Huxley A. F. , Julian F. J.
Published: December 2014

1. An apparatus is described by which the length of a selected part of an isolated muscle fibre can be held constant, giving isometric conditions, or alternatively its length can be measured while tension is held constant (isotonic). Control can be switched between length and tension so as to carry out afterloaded contractions with a shortening stop.

2. When a part of a fibre with uniform striation spacing is stretched so far that there is presumably no overlap of filaments, the tension developed during an isometric tetanus with this apparatus is very small (not more than 3‐5% of the tension developed at optimum length).

3. If the tendon ends are held stationary, a fibre with the same initial length develops a large amount of tension (order of 30‐40% of tension at optimum length) with a slow time course. This additional tension is due to shortening of the end parts of the fibre, where the striation spacing is smaller and overlap of filaments still exists.

4. The resistance to elongation of a part of a fibre where there is no overlap is only slightly increased on stimulation.

5. To a first approximation, the results are in good agreement with expectations based on the sliding filament theory. The development of detectable amounts of tension, and of a slight increase of stiffness, on stimulation, are however not expected on the simplest form of this theory; possible explanations are discussed.