bluuebunny/crossref_metadata_2025 huggingface dataset:
Competitive antagonism by phentolamine of responses to biogenic amines and the transmitter at a neuroglandular junction.
Authors: Bowser-Riley F , House C R , Smith R K
Published: December 2014

1. A quantitative study has been made of phentolamine's inhibition of the electrical and secretory responses of the isolated salivary glands of Nauphoeta cinerea Olivier to nerve stimulation and bath applications of agonists. 2. The results suggested that phentolamine is a competitive antagonist having an affinity constant of about 1 micrometer‐1 for the receptors for dopamine, noradrenaline, adrenaline and the neurotransmitter. 3. Phentolamine also inhibited responses to 5‐hydroxytryptamine in a manner seemingly more complex than competitive antagonism. Attempts to estimate the affinity constant gave values of about 0.08 and 0.015 microgram‐1 for inhibition of the secretory and electrical responses respectively. 4. This investigation showed that phentolamine discriminates between two kinds of receptor in this gland, one binding 5‐hydroxytryptamine and the other combining with catecholamines and the neurotransmitter.
An analysis of excitatory junctional potentials recorded from arterioles.
Authors: Hirst G D , Neild T O
Published: December 2014

1. Arterioles were impaled with two independent micro‐electrodes, one to pass current and the other to record membrane potential. 2. When current was injected into one branch of an arteriole, a membrane potential change could be detected either in the same branch or in an adjoining branch indicating that the arteriolar smooth muscle cells were electrically connected. 3. Fine dissection of the arteriolar tree gave short segments of arteriole which appeared to behave electrically as short cables with sealed ends. 4. Analysis of the electrotonic potentials recorded from isolated segments of arterioles allowed a determination of the arteriole cable properties. 5. Using the data from the cable analyses it was concluded that the junctional current underlying an excitatory junction potential has a duration that is brief when compared with that of the potential.
Ouabain‐sensitive fluid accumulation and ion transport by rabbit blastocysts.
Authors: Biggers J D , Borland R M , Lechene C P
Published: December 2014

1. By incubating 6‐day post‐coitum (p.c.) blastocysts in medium supplemented with either 20 mM‐sucrose or 10 mM‐KCl it was possible to show that the trophectoderm of the blastocyst prevents the concentration of K in the blastocoele fluid rising to external concentrations. 2. The concentrations of K in the blastocoele fluid are maintained predominantly by leakage of K from the trophoblast cells into the blastocoele and by ouabain‐sensitive transport of K into the trophoblast cells from the blastocoele fluid. 3. Exposure of blastocysts to ouabain on the juxtacoelic, but not abcoelic, surface of the trophectoderm may inhibit blastocoele fluid accumulation.
Amino acid pharmacology of mammalian central neurones grown in tissue culture.
Authors: Barker J L , Ransom B R
Published: December 2014

1. Spinal and cerebellar‐brainstem areas of fetal mouse were dissociated and grown in tissue culture until large enough to permit stable intracellular recording. 2. The tissue‐cultured neurones, growing as a monolayer and accessible under direct vision using phase contrast optics, allowed precise placement of intracellular recording and extracellular ionophoretic pipettes. 3. Ionophoresis of GABA and glutamate revealed a non‐uniform distribution of responses over the cell surface, with a lack of spatial coincidence in sensitivity between the two. GABA inhibited and glutamate excited all cells tested. 4. GABA responses evoked at the cell body and on nearby process membrane were almost uniformly hyperpolarizing, while those at some peripheral process membrane were either hyperpolarizing, depolarizing or a combination of both events. All responses were associated with an increase in membrane slope conductance. 5. Membrane polarization showed that all hyperpolarizing events extrapolated to about the same inversion potential, which averaged about 9 mV more negative than resting potential (n = 95 cells). The depolarizing phases of responses evoked at peripheral membranes extrapolated to about 0 mV (n = 5 cells). 6. The hyperpolarization and increase in membrane conductance of GABA responses at the cell body were dependent on Cl‐ ions and the inversion potential of the response was dependent on the Cl‐ ion concentration gradient. The inversion potentials of GABA, glycine and beta‐alanine responses were identical. 7. When matched in magnitude for evoked conductance increase, glycine responses decayed more rapidly than GABA. Glycine and beta‐alanine voltage responses both decayed faster than GABA responses of comparable size. 8. In about half the cells tested sustained or rapidly repeated application of GABA and glycine transformed hyperpolarizing responses into depolarizations which were associated with a maintained conductance increase. Results from conditioning‐test experiments with pairs of GABA and glycine responses suggest that the reversal of response polarity is due to a rapid redistribution of Cl‐ ions. 9. The limiting slope of log‐log dose‐response curves for GABA‐induced conductance averaged about 2, while those for glutamate‐induced depolarizations averaged about 1. The results suggest that two molecules of GABA and one molecule of glutamate participate in the respective post‐synaptic responses. 10. The observation indicate that mammalian C.N.S. tissue grown in culture is a suitable model to study C.N.S. membrane pharmacology with increasing precision.
Non‐parallel enzyme secretion from rat pancreas: in vivo studies.
Authors: Dagorn J C
Published: December 2014

The secretion of amylase, lipase and chymotrypsinogen was measured in the pancreatic juice of anaesthetized rats. 1. Stimulation of the protein secretion by I.V. cholecystokinin‐pancreozymin (8 IDU kg‐1) given together with secretin (5 CU kg‐1) resulted in a change in the enzyme proportions in pancreatic juice, characterized by decreases in the amylase to chymotrypsinogen and amylase to lipase ratios. 2. The same phenomenon was elicited by pilocarpine (15 mg kg‐1) associated with secretin (5 CU kg‐1) but not by secretin alone. 3. Blockade of protein synthesis by cycloheximide did not suppress the induction of non‐parallelism by stimulation. 4. It was concluded that the exocrine proteins are stored in two pools in which the proportions of enzymes are different. 5. With the help of a mathematical model it is proposed that one pool which corresponds to less than 0.35% of total enzyme storage, is responsible for basal secretion and is not sensitive to stimulation. The second (preponderant) pool provides secretion with a protein output increasing with stimulation.
Localization of the effect of acetylcholine in regulating intestinal ion transport.
Authors: Browning J G , Hardcastle J , Hardcastle P T , Redfern J S
Published: December 2014

1. The location of the site involved in the secretory response of rat jejunum and colon to ACh was investigated by selectively damaging either the villi of the jejunum and the surface epithelium of the colon or the crypts. 2. The secretory response induced by ACh was measured both in terms of changes in electrical activity and chloride fluxes. 3. Exposure of the mucosa to 2 M‐Na2SO4 for 30 min selectively damaged the jejunal villi and colonic surface epithelium but did not reduce the increased potential difference and current generated by ACh. 4. When resistance changes were taken into account the colonic response was markedly increased after Na2SO4 treatment although the jejunal response was unchanged. Under control conditions ACh reduced net Na absorption and stimulated Cl secretion by the colon. After exposure to Na2SO4 only the Cl secretory component of the ACh response remained, thus accounting for the enhanced effect. 5. Cycloheximide, administered I.V. at a dose of 12 mg/kg, damaged the crypts after 2 hr without affecting the villi of the jejunum or the surface epithelium of the colon. After cycloheximide treatment the increased potential difference, current and net Cl secretion induced by ACh were significantly reduced. 6. The crypts therefore appear to be the site primarily involved in the secretory response of rat jejunum and colon to ACh, although in the colon an inhibitory effect on the Na transport process located in the surface epithelium was observed.
Properties of the calcium‐extruding mechanism of liver cells.
Authors: Cittadini A , Van Rossum G D
Published: December 2014

1. The movements of Ca2+ between liver slices and the suspending medium have been followed with a Ca2+‐specific electrode and with measurements of the efflux of 45Ca. 2. A net entry of Ca2+ into the tissue occurred during anaerobiosis. Reoxygenation of the medium resulted in a net extrusion of Ca2+ which was reversed by the addition of a respiratory inhibitor (Amytal), an uncoupler of oxidative phosphorylation (pentachlorophenol) or the divalent‐cation‐specific ionophore, A23187. 3. The net extrusion of Ca2+ was dependent on the presence of Mg2+ in the medium, but was not prevented by ouabain or by incubation in a Na+‐free medium. Extrusion was not prevented by cytochalasin B or colchicine. 4. The undirectional efflux of 45Ca required Mg2+ to attain its maximal rate, and the magnitude was not affected by the presence of ouabain or the absence of Na+ from the medium. 5. It is concluded that extrusion of Ca2+ from liver cells is a metabolically dependent transport process that occurs independently of the exchange of Na+ between tissue and medium.
A morphological study of the axons and recurrent axon collaterals of cat alpha‐motoneurones supplying different hind‐limb muscles.
Authors: Cullheim S , Kellerth J O
Published: December 2014

1. Intracellular injections with horseradish peroxidasewere performed in cat alpha‐motoneurones supplying various hind‐limb muscles. 2. Ten alpha‐motoneurones from each of the quadriceps, posterior biceps, gastrocnemius‐soleus and anterior tibial pools as well as from the pool supplying the short plantar muscles were collected for morphological analysis of the intramedullary axonal systems including the recurrent axon collaterals. 3. The diameter of the alpha‐motor axons showed considerable variation within each motoneurone pool, the total range being from 4.6 to 9.0 micrometer. No significant difference in mean axon diameter was obtained between the different pools. 4. All alpha‐motoneurones supplying the short plantar muscles and one single alpha‐motoneurone supplying the quadriceps muscle lacked collaterals completely, while the remaining motoneurones gave off one to five collaterals. 5. The number of axon collateral outbulgings, interpreted as synaptic boutons, wihch originated from a single alpha‐motoneurone showed large variation within each pool that possessed axon collaterals, the total range being from seventeen of 158. The mean number varied from forty‐four (quadriceps) to eighty‐two (anterior tibial). 6. The axon collateral outbulgings were distributed not only in the Renshaw cell area ventromedial to the main motor nuclei but also in those parts of the motor nuclei which were located in the vicinity of the parent cell bodies. In the rostrocaudal direction, the outbulgings were distributed within a distances of less than 1 mm around the position of the parent cell bodies. 7. Some physiological implications of the lack of axon collaterals from alpha‐motoneurones supplying the short plantar muscles were discussed in relation to the functional characteristics of plantar muscles and motor units.
The role of calcium in the receptor mediated control of potassium permeability in the rat lacrimal gland.
Authors: Parod R J , Putney J W
Published: December 2014

1. In the presence of extracellular Ca, adrenaline stimulated a large increase in the rate of K (86Rb) release from rat lacrimal slices, followed by a lower, more sustained rate. 2. In the absence of extracellular Ca, adrenaline elicited only a transient release of 86Rb. 3. The artificial introduction of Ca into the cytosol by the ionophore A‐23187 could also initiate the release of 86Rb. 4. In a zero‐Ca medium, if either adrenaline or carbachol produced a transient release of 86Rb, the tissue could not respond to the other agonist with a transient release unless Ca was momentarily reintroduced to the medium. 5. If Ca was present in a limiting concentration, the Ca‐dependent rate of 86Rb release elicited from a lacrimal slice exposed simultaneously to carbachol and adrenaline was not significantly different from the release seen with carbachol alone. 6. It is concluded that the agonist‐induced release of K from the lacrimal gland consists of both a Ca‐independent phase which is initiated by the release of a limited pool of Ca, and a Ca‐dependent phase which is mediated by the influx of extracellular Ca. 7. It is also concluded that both alpha‐adrenergic and muscarinic receptor occupation activate a common, post‐receptor mechanism which may be responsible for both phases of K release.
Propagating calcium spikes in an axon of Aplysia.
Authors: Horn R
Published: December 2014

1. Intracellular recordings were obtained from the axon of the giant neurone R2 of Aplysia in order to study the ionic dependency of action potentials. 2. The overshoot potential of the axon spike increases with Na concentration in the manner predicted for a Na electrode. The maximum rate of rise (Vm) is linearly related to Na concentration. The overshoot potential is insensitive to Ca concentration at Na concentrations as low as 250 mM. 3. Tetrodotoxin (TTX) or replacement of Na with Tris abolishes action potentials in the axon but not soma of R2. Addition of 4‐aminopyridine to a Na‐free solution permits axon spikes to be generated. These action potentials are blocked by 30 mM‐Co2+, but not by TTX. The overshoot potential and Vm of these action potentials increase monotonically with Ca concentration. 4. Axonal action potentials can be generated when an equimolar concentration of Sr is substituted for all of the Ca and Mg in Na‐free medium. These action potentials are abolished by 30 mM‐Ca2+ or mM‐Co2+, and increase with Sr concentration. 5. TTX‐resistant Ba spikes can similarly be elicited in R2 axon. These action potentials are reduced by Ca, Co, or Cd, and enhanced by raising the Ba concentration. 6. The Vm of Na spikes in the absence of Ca is greater in the axon than in the soma of R2, whereas the Vm of divalent spikes is greater in the soma. 7. During repetitive stimulation the axon spikes incrase in duration. This broadening is inhibited by replacing Ca in the bath with Mn or by the addition of 30 mM‐CoCl2, and is enhanced by raising the Ca concentration by 30 mM. 8. The action potention of R2 axon has a mixed Na/Ca dependency. The density of Ca current may be greater in the some than in the axon of this cell.
Dopamine receptors in the central thermoregulatory pathways of the rat.
Authors: Cox B , Kerwin R , Lee T F
Published: December 2014

1. Intrahypothalamic injection of either dopamine (10 microgram) or apomorphine (10 microgram) in a dose volume of 1 microliter. caused an almost immediate rise in tail skin temperature and a concomitant fall in core temperature in the conscious rat maintained at an ambient temperature of 17 +/‐ 1 degrees C. 2. The location of the dopamine‐sensitive site was defined more accurately by reducing the dose volume to 0.5 microliter. and injecting dopamine at different points throughout the preoptic and anterior hypothalamic region. 3. The largest mean fall in core temperature (1.13 +/‐ 0.22 degrees C) was obtained after injection into the preoptic region. Injections with their perimeters more than 0.4 mm rostral or caudal to this site were ineffective. 4. Rats placed 0.65 m below a 250 W infra‐red lamp responded to the imposed heat load by vasodilation of the tail skin blood vessels, indicated by an increased tail skin temperature. 5. Bilateral, but not unilateral, injection of either pimozide (0.5 microgram) or haloperidol (2.5 microgram) into the preoptic region significantly reduced the increase in tail skin temperature so that the rats were less able to withstand the imposed heat load. 6. Three serial sections (0.5 mm thick) were prepared from the preoptic anterior hypothalamic region of the rat brain, one anterior, one posterior and one corresponding to the dopamine‐sensitive site. 7. Tissue from the middle slice increased its rate of synthesis of 3,5‐cyclic AMP in response to addition of dopamine 20 or 100 micron to the incubation medium. The posterior slice was inactive, but the anterior slice had similar activity to the middle slice. 8. The effect of dopamine on the middle slice was specifically blocked by haloperidol (0.1 micron), whereas the effects on the anterior slice were partially blocked by both haloperidol (0.1 micron) and propranolol (0.1 micron). 9. These results indicate that there is within a well defined area of the preoptic region a population of dopamine receptors, which play a part in the transmission of information from warm sensors to heat loss effectors.
Adrenergic and 'non‐adrenergic' components in the contractile response of the vas deferens to a single indirect stimulus.
Authors: McGrath J C
Published: December 2014

1. The mechanical response of the longitudinal smooth muscle of the rat vas deferens to stimulation of its motor nerves by a single pulse has been examined. The motor nerves were stimulated in vivo via the spinal outflows in the pithed rat or in vitro by field stimulation. 2. The contraction in the whole vas consisted of two components, an initial, rapid, brief contraction reaching a maximum at 300 msec and a second, slower and more prolonged contraction reaching its maximum at 600 msec. When the isolated vas was divided into prostatic and epididymal halves the contribution of these two components varied. The initial rapid component was more prominent in the prostatic half and the slower, second component more prominent in the epididymal half. Lowering the bath temperature caused, in both halves, these two components to merge into a single, slow, prolonged response. Both components were more rapid and briefer than the equivalent response of rat anococcygeus. 3. The second, slow component was abolished by alpha‐adrenoceptor antagonist drugs, potentiated and prolonged by drugs which inhibit the neuronal uptake of noradrenaline and absent from tissues taken from rats pre‐treated with reserpine, suggesting that the neurotransmitter for this component is noradrenaline. 4. These experiments were extended to the mouse or guinea‐pig vas deferens. Both showed the same two component mechanical response as the rat vas and in both the second, slow component was preferentially inhibited by alpha‐adrenoceptor antagonists and potentiated by drugs blocking noradrenaline uptake. 5. Drugs known to reduce the response to repetitive nerve stimulation of the vas were examined for their effect on the response to a single stimulus. Lysergic acid diethylamide preferentially inhibited the second, slow phase of contraction whereas apomorphine preferentially inhibited the first rapid phase. Guanethidine inhibited responses but any differential effects could not be analysed due to its stimulant properties. 6. These results show that there are two components even to the response to a single stimulus. The second of these appears to be adrenergic while the transmitter responsible for the first remains to be determined.
The correlation between ouabain binding and potassium pump inhibition in human and sheep erythrocytes.
Authors: Joiner C H , Lauf P K
Published: December 2014

1. [3H]Ouabain binding to human and sheep red blood cells was shown to be specific for receptors associated with Na/K transport. Virtually all tritium binding was abolished by dilution with unlabelled drug. Saturation levels of binding were independent of glycoside concentration and were identical to those associated with 100% inhibition of K pumping. 2. [3H]Ouabain binding and 42K influx were measured simultaneously in order to correlate the degree of K pump inhibition with the amount of glycoside bound. Results by this method agreed exactly with those obtained by pre‐exposing cells to drug, followed by washing and then measuring K influx. 3. Plots of [3H]oubain binding vs. K pump inhibition were rectilinear for human and low K (LK) sheep red cells, indicating one glycoside receptor per K pump site and functional homogeneity of pump sites. High K (HK) sheep red cells exhibited curved plots of binding versus inhibition, which were best explained in terms of one receptor per pump, but a heterogeneous population of pump sites. 4. External K reduced the rate of glycoside binding, but did not alter the relationship between binding and inhibition. 5. The number of K pump sites was estimated as 450‐‐500 per human cell and 30‐‐50 per LK sheep cell. HK sheep cells had 90‐‐130 sites per cell, of which eighty to ninety were functionally dominant. The number of K pump sites on LK sheep cells was not changed by anti‐L, although the maximum velocity of pump turnover was increased.
The physiological effects of monocular deprivation and their reversal in the monkey's visual cortex.
Authors: Blakemore C , Garey L J , Vital-Durand F
Published: December 2014

1. 1127 single units were recorded during oblique penetrations in area 17 of one normal, three monocularly deprived and four reverse sutured monkeys. 2. In all animals most cells outside layer IV c were orientation‐selective, and preferred orientation usually shifted from cell to cell in a regular progressive sequence. 3. The presence in layer IV c of non‐oriented, monocularly driven units, organized in alternating right‐eye and left‐eye 'stripes' (LeVay, Hubel & Wiesel, 1975) was confirmed. 4. Early monocular deprivation (2‐‐5 1/2 weeks) caused a strong shift of ocular dominance towards the non‐deprived eye. However, even outside layer IV c, neural background and some isolated cells could still be driven from the deprived eye in regularly spaced, narrow columnar regions. In layer IV c the non‐deprived eye's stripes were almost three times wider, on average, than the deprived. 5. Later monocular deprivation (11‐‐16 months) had no detectable influence on layer IV c but seemed to cause a small shift in ocular dominance outside IV c. Deprivation for 6 1/4 months in an adult had no such effect. 6. After early reverse suturing (at 5 1/2 weeks) the originally deprived eye gained dominance over cells outside layer IV c just as complete as that originally exercised by the eye that was first non‐deprived. 7. The later reverse suturing was delayed, the less effective was recapture by the originally deprived eye. Reversal at 8 weeks led to roughly equal numbers of cells being dominated by each eye; fewer cells became dominated by the newly open eye after reverse suturing at 9 weeks and most of them were non‐oriented; reversal at 38 1/2 weeks had no effect. 8. Binocular cells, though rare in reverse sutured animals, always had very similar preferred orientations in the two eyes. The columnar sequences of preferred orientation were not interrupted at the borders of ocular dominance columns. 9. Even within layer IV c there was evidence for re‐expansion of physiologically determined ocular dominance stripes. After early reverse suture, stripes for the two eyes became roughly equal in width. Possible mechanisms for these changes are discussed.
Chloride dependence of active sodium transport in frog skin: the role of intercellular spaces.
Authors: Ferreira K T , Hill B S
Published: December 2014

1. In agreement with previous observations the replacement of Cl by a nonpenetrating anion in the solution bathing either the outside or both sides of the frog skin causes a fall in the short‐circuit current. 2. When Cl is replaced by a non‐penetrating anion in the solution bathing the outside of the frog skin the Isc is still a correct measure of the net Na transport. 3. Under the same conditions both active and shunt paths seem to be affected since there is a decrease in Isc, Na influx, amiloride‐dependent conductance, and initial Na uptake across the external barrier, together with a decrease in Cl‐backfluxes and amiloride‐independent conductance. There is also a decrease in water permeability and a reduction in size of the intercellular spaces. 4. The removal of Cl does not appear to affect the entry step of Na but may have an effect on the shunt path. This in turn may change the active Na transport.
Movement‐sensitive and direction and orientation‐selective cutaneous receptive fields in the hand area of the post‐central gyrus in monkeys.
Authors: Hyvärinen J , Poranen A
Published: December 2014

1. In the hand area of the post‐central gyrus of three alert Macaca speciosa monkeys neurones related to cutaneous receptors but not activated by simple touch on the receptive field were recorded using the transdural micro‐electrode recording technique. Thirty‐six cells were found to have complex cutaneous receptive field properties. These neurones were subdivided into the following three groups. 2. Nine neurones were not activated by punctate stimuli on the receptive fields but responded well to movement along the skin. The activity of these neurones was not affected by the direction of movement; nor was it sensitive to different textures of the moving surface. 3. Eighteen neurones responded to cutaneous movement along the skin surface in a particular direction giving no response to stimulation in the opposite direction and intermediate responses to intermediate directions. Similar responses were evoked from different subparts of the receptive field. 4. Nine neurones responded well to an edge placed on the skin in an optimal orientation or moved along the skin in a direction perpendicular to the edge. A maximal response was produced by stimuli of the same optimal orientation in different parts of the receptive field. The significance of the stimuli to the monkey had only a minor influence on the magnitude of the responses of these neurones and no influence on the receptive field properties. 5. The occurrence of the complex cutaneous cells increased from anterior to posterior within the post‐central gyrus and most of them were found in Brodmann's area 2. Thus we postulate that the complex receptive field properties arise as a consequence of cortical processing in a network in which postsynaptic one‐way lateral inhibition generates the directional properties of the neurones. 6. The complex cutaneous neurones constituted only 6% of the neurones studied in the hand area of the post‐central gyrus. Thus the prevalence of neurones with elongated and direction‐selective receptive fields is low in the primary somatosensory cortex in comparison with the visual cortex. These neurones may, however, serve the sterognostic capcity of the hand by contributing information about stimulus motion, orientation and direction of movement on the skin.
Some anatomical and electrophysiological properties of tooth‐pulp afferents in the cat.
Authors: Lisney S J
Published: December 2014

1. The responses of nerves which could be excited by electrical stimulation of the canine tooth‐pulp were recorded from the trigeminal ganglion. 2. Preliminary experiments showed that the responses of mandibular canine pulpal afferents were recorded from the postero‐lateral part of the trigeminal ganglion whereas the responses of maxillary canine pulpal afferents were recorded from the central part of the ganglion. 3. The conduction velocity differed in various parts of these nerves; the conduction velocity inside the tooth tended to be slower than that from the tooth to the trigeminal ganglion; the mean conduction velocity in the part of the nerve peripheral to the trigeminal ganglion was faster than that in the part central to the ganglion, and in the central part the conduction velocity decreased caudally. 4. Collision experiments combining tooth stimulation and stimulation of sites in the trigeminal sensory nuclear complex were carried out to investigate the projections of individual pulpal afferents. 5. The results of these experiments showed that some tooth‐pulp afferents bifurcate and project to both the main sensory nucleus and the nucleus caudalis. For other pulpal afferents only a projection to the main sensory nucleus or the nucleus caudalis could be demonstrated. 6. Pulpal afferents that bifurcated had faster conduction velocities than those for which no bifurcation could be shown.
The distribution of sodium, potassium and chloride in the nucleus and cytoplasm of Bufo bufo oocytes measured by electron microprobe analysis.
Authors: Dick D A
Published: December 2014

1. Measurements of cytoplasmic and nuclear Na, K and Cl have been made by electron microprobe analysis on freeze‐dried sections of oocytes of Bufo bufo, using standards of bovine plasma albumin and gamma‐globulin. Concentrations were obtained per kilogram of dry mass, were converted to concentrations per litre of water content using known figures for water and solid concentration of nucleus and cytoplasm, and were then compared with measurements on cells from the same animal obtained by flame photometry. 2. In fresh oocytes concentrations were (mean +/‐ S.E. of mean in m‐mole/l. H2O) in cytoplasm Na 10.9 +/‐ 1.95, K 70.2 +/‐ 3.22, Cl 98.8 +/‐ 11.0, and in nucleus Na 10.4 +/‐ 1.79, K 266.4 +/‐ 22.8, Cl 91.3 +/‐ 9.0. 3. After treatment with Na‐free Ringer (Li substituted for Na) for 5 hr, concentrations were in cytoplasm Na 11.1 +/‐ 2.44, K 64.4 +/‐ 5.7, Cl 88.7 +/‐ 8.8, and in nucleus Na 2.4 +/‐ 0.73, K 141 +/‐ 13.9, Cl 75.0 +/‐ 6.7. Na inexchangeable with Li therefore lay in the cytoplasm but not in the nucleus as previously shown by autoradiography. 4. For K electron microscopic analysis measurements agreed well with those obtained by flame photometry but the former measured only 35% of Na measured by flame photometry. This discrepancy may be due either to technical difficulties with the electron microprobe analysis or to localization of Na in the cytoplasm.
Mucosal receptors in the gastric antrum and small intestine of the rat with afferent fibres in the cervical vagus.
Authors: Clarke G D , Davison J S
Published: December 2014

1. Electrical stimulation of the abdominal vagi revealed that abdominal vagal fibres are distributed throughout the cervical vagal trunk. Conduction velocities of the main group of abdominal fibres ranged from 0.4 to 1.5 m.sec‐1. 2. Thirty‐seven single afferent fibres, with endings in the gastric and intestinal mucosa, were isolated from the cervical vagus of adult rats. Conduction velocities of eighteen of these endings ranged from 0.5 to 2.5 m.sec‐1. 3. Light mechanical stimulation, such as stroking the mucosa, evoked a rapidly adapting response from these endings. Sustained pressure or distension with fluid or air did not excite these endings although excessive stretching of the mucosa excited three units. Balloon distension usually evoked an 'on‐off' response due to phasic stimulation of the mucosa by the balloon during inflation and deflation. 4. These same endings also functioned as non‐specific, slowly adapting chemoreceptors responding to various organic and inorganic acids, tap water and distilled water, alcohol, hypertonic saline, NaOH, NH4Cl, CuSO4, casein hydrolysate, mustard powder and cayenne pepper. Hypertonic glucose and guinea‐pig bile were ineffective as stimuli. 5. In the presence of an excess of chloride ions the effectiveness of acids in stimulating these endings was in part determined by the pK of the acid. However pH per se was not the basic determining factor but rather the molecular size of the acid.
Role of joint afferents in motor control exemplified by effects on reflex pathways from Ib afferents.
Authors: Lundberg A , Malmgren K , Schomburg E D
Published: December 2014

1. Intracellular recording from motoneurones to hind limb muscles in the cat was used to investigate the effect of volleys in the posterior nerve to the knee joint on motoneurones and on transmission from Ib afferents. 2. Volleys in the joint nerve facilitate transmission in disynaptic and trisynaptic inhibitory and excitatory reflex pathways from Ib afferents. It is postulated that facilitation, which appears at a strength of 1.5 times threshold, is evoked, not by Ib afferents which 'contaminate' the joint nerve, but by afferents from joints receptors. 3. T;e time course of facilitation of the disynaptic Ib i.p.s.p.s in motoneurones indicates that these joint afferents have disynaptic connexions with the interneurones of the Ib inhibitory pathway. 4. A brief description is given of synaptic effects evoked in motoneurones by graded electrical stimulation of the posterior nerve to the knee joint. At low stimulus strength the effects may be evoked via interneurones of Ib reflex pathways, but some results suggest that other interneuronal paths are utilized as well. Somewhat higher strengths, but occasionally less than 2 times threshold, produce later synaptic effects presumably mediated by reflex paths from the flexor reflex afferents; it does not seem likely that the contributory afferents in the joint nerve have nociceptive function. 5. It is suggested that impulses from impulses from joint receptors can influence tension regulation from Golgi tendon organs; if these receptors are activated in the terminal phase of the movement they may contribute a purposeful decrease of tension. It is pointed out that joint receptors may have an important role in motor regulation by their effects on interneurones of the different neuronal systems controlling motoneurones.
The distribution of motoneurones supplying chick hind limb muscles.
Authors: Landmesser L
Published: December 2014

1. The motor nuclei supplying many of the hind limb muscles were localized in late chick embryos (stage 36‐37; 10‐11 days) by utilizing the technique of retrograde transport of horseradish peroxidase. 2. Each nucleus was found to be localized in a characteristic position in both the rostro‐caudal and transverse plane of the spinal cord with only slight individual variation. 3. Each motor nucleus consisted of an elongate, coherent cluster of labelled cells, with few cells occurring outside the cluster. Thus, there did not appear to be extensive overlap of nuclei nor extensive intermingling of motoneurones projecting to different muscles. 4. The position of a motor nucleus in the transverse plane was not correlated with whether its muscle was used as an extensor or flexor; nor were adjacent nuclei necessarily co‐activated during normal unrestrained walking movements as deduced from e.m.g. recordings. The position of a motor nucleus also was not correlated in a topographical manner with the adult position in the limb of the muscle to which it projected. 5. Further, while no correlation was found between the rostrocaudal position of a motor nucleus and the embryonic muscle mass from which its muscle was derived, such a relationship existed for the medio‐lateral position; all muscles arising from the dorsal muscle mass, regardless of their function or adult position, were innervated by laterally situated motoneurones, all muscles arising from the ventral muscle mass by medially situated motoneurones. 6. It is concluded that motoneurone position is most closely correlated with ontogenetic events presumaeriphery. It can also be inferred that the central connexions onto motoneurones, responsible for their proper activation, cannot be achieved by a simple mechanism based largely on the position of the motoneurone soma.
Inhibition by metiamide of secretagogue‐induced gastric acid secretion in the conscious Heidenhain pouch rat.
Authors: Bunce K T , Parsons M E
Published: December 2014

1. The inhibition by metiamide of gastric of gastric acid secretion in response to histamine, pentagastrin and bethanechol has been investigated in the conscious Heidenhain pouch rat. 2. Histamine alone stimulated only a low rate of acid secretion. This response was markedly potentiated in the presence of mepyramine. 3. Metiamide at a dose of 0.15 mumole . kg‐1 . min‐1 I.V. significantly inhibited the acid secretory responses to histamine (in the presence of mepyramine) and pentagastrin. In each case the inhibition of acid output was the result of a significant decrease in both secretory volume and acid concentration. 4. Metiamide at a dose of 0.15 mumole . kg‐1 . min‐1 I.V. did not inhibit bethanechol‐stimulated acid secretion. Increasing the dose of metiamide to 1.0 mumole . kg 1 . min‐1 I.V. did produce a significant inhibition. In contrast with histamine and pentagastrin, metiamide inhibited bethanechol‐stimulated secretion only by reducing acid concentration; there was no significant decrease in the gastric secretory volume. 5. It is concluded that these results are consistent with the view that histamine and pentagastrin share a common pathway in stimulating gastric acid secretion in the rat. The role of histamine in the control of bethanechol‐stimulated acid secretion remains unclear.
Analysis of periodic changes in ventilation in new‐born infants.
Authors: Hathorn M K
Published: December 2014

1. Ventilation was recorded in thirty term infants during the first week after delivery using the trunk plethysmograph, during periods of rapid eye movement sleep (r.e.m.) and quiet sleep (n.r.e.m.). 2. Continuous histograms of tidal volume (VT) and instantaneous respiration rate (f) were samples at 0.5 sec intervals, passed through a digital filter to remove long‐term trends in the data, and then subjected to frequency analysis. 3. In all the infants oscillations in VT and f were detected, with mean periods varying from 6.7 to 12.5 sec. The amplitude of these oscillations was higher during r.e.m. than n.r.e.m. sleep in all the infants. 4. The oscillations in VT tended to be out of phase with those for f, particularly during n.r.e.m. sleep; this contrasted with in‐phase oscillations in VT and f found during periodic breathing in an additional six premature infants studied.
Recruitment order of human spindle endings in isometric voluntary contractions
Authors: Burke David , Hagbarth Karl-Erik , Skuse Nevell F.
Published: December 2014

1. The responses of twenty‐two spindle endings in the anterior tibial and toe extensor muscles of human subjects were studied during isometric voluntary contractions of the receptor‐bearing muscle with the ankle joint fixed in 25° plantar flexion.

2. The discharge of eighteen endings accelerated in voluntary contractions when the contraction strength exceeded a threshold level which differed for different endings but was reproducible for the same ending.

3. With contractions of slow onset the latency to spindle acceleration varied with the speed of onset of the contraction. Endings with a background discharge were often unloaded by contractions until the contraction strength exceeded the threshold for activation of the ending.

4. No correlation was found between the sensitivity of a spindle to external length changes and its ease of activation in a voluntary contraction. For two spindle endings with a background discharge there was no change in either discharge frequency or the regularity of spindle discharge during contractions which were below the threshold for activation of the endings. It is concluded that the threshold for activation of a spindle ending in an isometric voluntary contraction is determined by its fusimotor innervation, and that fusimotor neurones probably have a recruitment order, much as do skeletomotor neurones.

5. Once activated, the discharge of spindle endings fluctuated with changes in skeletomotor activity but the relationship for some endings contained non‐linearities. Such non‐linearities were not as apparent in multi‐unit recordings from a number of spindle endings in the contracting muscle. It is concluded that the fusimotor drive to a muscle is proportional to the skeletomotor drive to the muscle, and that skeletomotor and fusimotor neurones are subjected to similar if not identical descending command signals. From the work of Evarts (1968), it seems likely that these command signals are related more to desired muscle force than to desired muscle length.
Rapid orthograde and retrograde axonal transport of acetylcholinesterase as characterized by the stop‐flow technique.
Authors: Brimijoin S , Wiermaa M J
Published: December 2014

1. In rabbit peroneal nerves incubated in vitro at 37 degrees C, acetylcholinesterase (AChE) activity accumulated at both borders of a short region cooled to 5 degrees C. Accumulation was unaffected by concentrations of cycloheximide that inhibited 86% of local protein synthesis, as measured by the incorporation of [3H]leucine. It is probable that the local changes in enzyme activity during incubation reflected redistribution of the enzyme by axonal transport. 2. AChE activity accumulated almost three times faster at the proximal than at the distal border of cooled regions. This suggests that three times more enzyme is normally exported from nerve cell bodies than is returned to them, as though most of the transported AChE were degraded or secreted from distal parts of the neurones. The rates of accumulation of enzyme activity were consistent with average velocities of transport of 24 mm/day in the distal (orthograde) direction and 8.6 mm/day in the proximal (retrograde) direction. 3. When nerves that had been locally cooled for 3 hr were rewarmed to 37 degrees C, the accumulated AChE activity moved rapidly away from the cooled region. More than half of the activity appeared in a wave moving distally with a maximum velocity of 400 +/‐ 35 mm/day. A smaller wave moved proximally with a maximum velocity of 288 mm/day. 4. The observed behaviour of AChE is direct evidence that a small amount of this enzyme, probably less than 10% of the axonal content, is normally transported away from cell bodies as rapidly as any substance known. A still smaller amount of the enzyme is subject to an almost equally rapid retrograde transport. However, 85% of the AChE in peripheral nerve appears to be stationary, which probably explains why the average velocity of transport of this enzyme is so low.
Mechanism of the vibration paradox: excitatory and inhibitory effects of tendon vibration on single soleus muscle motor units in man
Authors: Desmedt John E. , Godaux Emile
Published: December 2014

1. The parameters of presynaptic inhibition of the Ia spindle afferents from soleus muscle by vibration have been investigated. The inhibitory effects increase with the amplitude of vibration, but decrease when the vibration frequency is increased.

2. The monosynaptic reflex threshold of twenty‐one single soleus motor units activated in the H (Hoffmann) reflex by a single electrical stimulus to the posterior tibial nerve was estimated quantitatively and expressed in relation to the size of the simultaneously recorded H reflex.

3. A parametric study of the effects of various Achilles tendon vibrations on the reflex threshold of the single soleus motor units indicated that their order of derecruitment is concordant with their rank order for activation in the phasic reflexes of the soleus. The last recruited motoneurones are the most susceptible to being silenced by steady vibration.

4. Muscle vibration progressively recruits single motor units according to the motoneurone size principle through polysynaptic proprioceptive pathways. However the presynaptic inhibition of Ia spindle afferents simultaneously induced by the vibration works in reverse on the same rank order of motoneurones of the soleus spinal pool, thereby limiting the polysynaptic recruitment of units in the tonic vibration reflex while depressing the autogenic phasic proprioceptive reflexes. These mechanisms elucidate the so‐called vibration paradox and extend the size principle of Henneman to presynaptic inhibitory effects.
Increased formation of diamines and polyamines in the pregnant rat.
Authors: Andersson A C , Henningsson S , Rosengren E
Published: December 2014

1. The urinary excretion of histamine, methylhistamine, putrescine, cadaverine, spermidine and spermine was examined before, during and after pregnancy in rats. 2. During the last third of undisturbed pregnancy a distinct and steep rise occurred in the excretion of all amines studied except spermine. The peak values were found a few days before the birth of the young. In spermidine excretion a second peak was observed one or two days after delivery. 3. Before and during the first 2 weeks of gestation on a molar basis putrescine excretion was the greatest one. During the last trimester histamine was excreted in the largest amount. 4. Under the influence of the diamine oxidase inhibitor aminoguanidine the general pattern of excretion of diamines and polyamines in pregnant rats remained essentially unchanged but the total amount excreted increased. Most conspicuous was the great elevation of urinary contents of putrescine and cadaverine.
Measurement of calcium influx under voltage clamp in molluscan neurones using the metallochromic dye arsenazo III.
Authors: Ahmed Z , Connor J A
Published: December 2014

1. The metallochromic indicator dye, arsenazo III, was injected into somata of molluscan neurones from Archidoris monteryensis. Membrane current and dye absorbance change were simultaneously monitored under voltage clamp. 2. Absorbance measured at 660 nm increased during positive‐going voltage steps large enough to activate membrane conductances. In situ idifference spectra were qualitatively similar to dye, dye‐calcium difference spectra recorded in vitro. The absorbance change was abolished by either a thorough removal of external calcium or internal chelation of calcium by EGTA. It was concluded that the absorbance increase primarily reflected changing internal calcium concentration and that the calcium entered from the outside. 3. Dye absorbance increased in a nearly linear fashion during voltage clamp pulses of 100‐‐300 msec duration. This is in qualitative agreement with electrical stuidies which demonstrated only fractional inactivation of calcium conductance during such periods. Plots of absorbance change vs. Vm peaked at +30 to +40 mV and fell off sharply until approximately +70 mV where the slope became less steep. A null or reversal of the absorbance change was generally observed aroung +110 mV. Evidence is presented that calcium influx was in some cases sufficient to cause sizeable changes in its equilibrium potential. 4. During multisecond voltage clamps the slope of the absorbance change showed a large decline. Where barium substituted for calcium as the influx species in identical clamps, the absorbance at 660 nm also increased but in a much more linear fashion. Except for a slight effect on the initial few pulses, the absorbance signal did not recover after a period of barium influx. These results suggest that part of the slope decline might result from processes related to calcium uptake and not to membrane conductance decrease. 5. Dye absorbance changes during normal and TEA action potentials were measured. Comparison of these changes with voltage clamp records indicated that calcium influx during a spike was capable of raising concentration by roughly 2 X 10(‐7) M if the cell were considered to be a uniform sphere with no buffering capacity. Calcium influx during action potentials was increased dramatically by TEA, primarily as a result of a prolonged plateau phase. The existence and duration of the plateau was controlled mainly by potassium conductance systems, however. There was no evidence found for facilitation of the calcium conductance. 6. Following a moderate influx of calcium it required 20‐‐60 sec, depending on the neurone, for the dye absorbance to return to base line (at 9 degrees C). The recovery time course showed a marked difference when examined at different wavelengths. For lambda = 660 nm there was an initial period in which the absorbance decreased rapidly, followed by a slower phase which generally carried the absorbance below the initial (prepulse) value...