bluuebunny/crossref_metadata_2025 huggingface dataset:
Short‐latency projections to the cat cerebral cortex from skin and muscle afferents in the contralateral forelimb
Authors: Oscarsson O. , Rosén I.
Published: December 2014

1. The potentials evoked in the first sensorimotor area on stimulation of muscle and skin nerves in the contralateral forelimb were recorded in preparations with either the dorsal funiculus (DF) or the spinocervical tract (SCT) interrupted.

2. The short‐latency, surface‐positive potentials in these preparations are mediated by the remaining path, either the DF or SCT.

3. Cutaneous afferents project through both paths to two discrete areas which correspond to the classical sensory and motor cortices (Fig. 10 A and B). The projection areas are not identical: the DF path seems to activate most effectively the sensory cortex; and the SCT path, most effectively the motor cortex.

4. The potentials evoked from cutaneous nerves have a similar latency in the two areas. On stimulation of the superficial radial nerve the latency was about 4·5 msec in preparations with intact DF, and about 5·3 msec in preparations with intact SCT.

5. High threshold muscle afferents project to the same areas as the cutaneous afferents.

6. Group I muscle afferents project, exclusively through the DF path, to an area distinct from the two cutaneous projection areas (Fig. 10C). It occupies a caudal part of the motor cortex and an intermediate zone between the sensory and motor cortices.

7. The projection areas are compared with the recent cytoarchitectonic map of Hassler & Muhs‐Clement (1964) (Fig. 10D).

8. It is suggested that the afferent projections to the motor cortex and the intermediate zone are used in the integration of movements elicited from the cortex. The general similarity in the organization of afferent paths to the motor cortex and the cerebellum is pointed out.
Interaction experiments on the responses evoked in Purkinje cells by climbing fibres
Authors: Eccles J. C. , Llinás R. , Sasaki K. , Voorhoeve P. E.
Published: December 2014

1. The uniquely powerful excitatory synaptic action of a single climbing fibre on a Purkinje cell in the cerebellum of the cat was tested during the intense and prolonged inhibitory action produced by the parallel fibre, basket and stellate cell system. There was depression of the later spike discharges, but the initial discharge was never suppressed.

2. With intracellular recording the excitatory post‐synaptic potential was depressed during the initial phase (about 10 msec) of the inhibitory action, but there was a later increase with a time course resembling the latter part of the inhibitory hyperpolarization. An explanation of these and other effects is given in terms of conventional ideas of excitatory and inhibitory synaptic interaction.

3. These observations on single Purkinje cells, particularly with intracellular recording, have helped in formulating a provisional explanation of the finding that during inhibition there is an increase in the negative field potential evoked by a climbing fibre volley.

4. The excitatory action of a climbing fibre synapse is shown to be greatly depressed immediately after a preceding activation and recovery takes hundreds of milliseconds. By the collision technique it is shown that the same climbing fibre is activated by inferior olive and juxta‐fastigial stimulation.

5. With rapid repetitive activation there was initially a progressive decline in the effectiveness of each successive impulse, but a steady level was soon reached. On cessation of a tetanus of twenty or more impulses there was a delayed recovery of the depolarization, which suggests a continued action of the accumulated transmitter.

6. With extracellular recording repetitive spike initiation continued with stimulation frequencies as high as 100/sec, but at still higher frequencies spikes were depressed by the intense synaptically evoked depolarization. On cessation of the stimulation after‐discharge often developed as the depolarization declined. The prolonged after‐discharges following severe tetani suggest that there is a very effective accumulation of the transmitter.
The action of antidromic impulses on the cerebellar Purkinje cells
Authors: Eccles J. C. , Llinás R. , Sasaki K.
Published: December 2014

1. Antidromic impulses have been set up in the axons of Purkinje cells of the cerebellar vermis by stimulation in the juxta‐fastigial (
J.F.) region. Most experiments were performed on the normal cat cerebellum, but in nine the cerebellum was chronically deafferented by bilateral pedunculotomy 9‐23 days previously.

2. Intra‐ and extracellular recording from Purkinje cells both showed a characteristic inflexion on the rising phase of the spike potential (the characteristic IS—SD inflexion) that presumably signals a delay in invasion between the axon and the large soma‐dendritic expansion.

3. Laminar field analysis of the antidromic spike potentials showed that the antidromic impulses invaded at least 200 μ of the main dendrites as well as the soma, there being then a steep decrement to the surface. At superficial levels there was even an inverse antidromic spike potential. There appeared to be a synchronous invasion of the soma‐dendritic complex, perhaps due to trigger zones of low threshold on the dendrites.

4. Antidromic soma‐dendritic invasion was modified in the expected manner by a volley in the parallel fibres; there was inhibition of transmission into the soma and up the main dendrites (maximum effect at 200‐300 μ depth) due to the inhibitory action of the basket and superficial stellate cells that are excited by the parallel fibres; there was facilitation of transmission in the dendrites at levels superficial to 200 μ due to the direct excitatory action of parallel fibres. Both the inhibitory and excitatory actions had a duration in excess of 100 msec.

5. In the chronically deafferented cerebellum a second
J.F. stimulation evoked a full size antidromic spike potential at an interval of 3 msec. There was a gradual decline in size down to intervals of about 2 msec, and at briefer intervals, to 1 msec, there was a small residual spike potential that possibly is due to transmission into the Purkinje cell axon collaterals at intervals too brief for soma‐dendritic invasion. With repetitive stimulation there was a well maintained soma‐dendritic invasion at a frequency as high as 300/sec.

6. In the chronically deafferented cerebellum an antidromic volley in the Purkinje cell axons caused a brief inhibitory silence of rhythmically discharging Purkinje cells. It is suggested that this is a direct inhibitory action of the Purkinje axon collaterals, that parallels their direct inhibitory action that has been demonstrated by Ito and collaborators (1964) on the intracerebellar nuclei and Deiters nucleus.

7. In the chronically deafferented cerebellum an antidromic volley in the Purkinje axons produced not only the large negative spike potential indicative of antidromic soma‐dendritic invasion, but also a later small and slow positive wave that appeared to be closely linked with the negative spike. It is shown how this would arise by current flow into the dendrites that had been depolarized but not excited by the initial antidromic invasion.
Transmission from perivascular inhibitory nerves to the smooth muscle of the guinea‐pig taenia coli
Authors: Bennett M. R. , Burnstock G. , Holman Mollie E.
Published: December 2014

1. Membrane potential changes of the smooth muscle cells of the taenia coli were recorded during stimulation of the perivascular inhibitory nerves.

2. Some spontaneous action potentials were preceded by a slow pacemaker‐like potential. Others began at or near the maximum level of the membrane potential and were not preceded by pacemaker‐like potentials.

3. There were no changes in the membrane potential of smooth muscle cells when the inhibitory nerves were stimulated with a single pulse. Stimulation at frequencies greater than 5 pulses/sec caused a hyperpolarization of the smooth muscle membrane. This resulted in a decrease in spike frequency and relaxation.

4. When the frequency of stimulation of the inhibitory nerves was increased there was an increase in the amplitude and rate of rise of the hyperpolarization and a decrease of the latency. The latency varied from 150 to 300 msec, and the largest hyperpolarization recorded was 16 mV.

5. The effect of the hyperpolarization due to nerve stimulation in cells showing pacemaker‐like activity was to increase the level of the membrane potential at which the action potentials began and to increase the membrane potential to which the action potentials repolarized. Action potentials which occurred during hyperpolarizations of the membrane had greater rates of rise and fall and larger amplitudes than did the action potentials which occurred before hyperpolarization.

6. The effect of the hyperpolarization due to nerve stimulation in cells which did not show pacemaker‐like activity depended on the amplitude of the hyperpolarization. Small hyperpolarizations exposed small depolarizations of the membrane which occurred when an action potential would normally have been expected. Large hyperpolarizations blocked the action potentials entirely.

7. Action potentials did not begin firing again at the normal rate immediately after stimulation ceased. The time taken for the rate of firing of action potentials to return to normal increased with increasing frequency of stimulation.

8. The hyperpolarization in response to perivascular inhibitory nerve stimulation was blocked by guanethidine and bretylium.
Transmission from intramural inhibitory nerves to the smooth muscle of the guinea‐pig taenia coli
Authors: Bennett M. R. , Burnstock G. , Holman Mollie E.
Published: December 2014

1. Membrane potential changes of smooth muscle cells were recorded during stimulation of the intramural inhibitory nerves to the taenia coli.

2. Stimulation across the taenia coli with single pulses of 200 μsec duration excites the intramural nerves and not the muscle directly.

3. The membrane potential changes due to stimulation of the intramural inhibitory nerves were different from those produced by perivascular inhibitory nerve stimulation in the following ways: hyperpolarizations (i.j.p.'s) of up to 25 mV were produced in response to single pulses; the latency, i.e. the time taken for the membrane to hyperpolarize after a stimulus of maximal strength, was as short as 80 msec; when the nerves were stimulated repetitively the membrane was hyperpolarized by up to 35 mV and all spontaneous activity was abolished; the mean hyperpolarization due to repetitive stimulation increased with the frequency of stimulation up to 10 pulses/sec and then remained constant; the hyperpolarization due to stimulation at frequencies greater than 5 pulses/sec was not maintained but decreased after 3‐5 sec of stimulation; and finally when stimulation had ceased action potentials commenced firing at frequencies greater than normal.

4. The amplitude and rate of hyperpolarization of the i.j.p. increased with increasing strength of stimulation until a maximum amplitude and rate of hyperpolarization was reached. The recovery or depolarizing phase of the i.j.p. was exponential with a time constant which varied from about 250 msec to 500 msec and could not therefore be due to the discharge of the membrane capacitance. In some cases there was an inflexion on this depolarizing phase and in these cases recovery led directly into an action potential.

5. Spontaneous hyperpolarizations of the membrane were seen in some cells, and these hyperpolarizations were similar to those recorded on submaximal stimulation of the intramural nerves.

6. There were no changes in the characteristics of the i.j.p. in the presence of guanethidine or bretylium.
Streaming potentials in the rat small intestine
Authors: Smyth D. H. , Wright E. M.
Published: December 2014

1. The effect of adverse osmotic pressure gradients on fluid transfer and electrical potential across the wall of sacs of rat everted small intestine was investigated.

2. Addition of mannitol to the mucosal fluid produced a potential change of 0·062 mV/m‐os
M and a decrease in fluid transfer of 0·015 ml./m‐os
M/hr. This is consistent with the production of streaming potentials due to fluid movement through negatively charged pores in the intestine.

3. The solute‐linked fluid movement does not pass through these negatively charged pores which are responsible for the streaming potentials.

4. From the magnitude and polarity of the streaming potential a value of —50 mV has been calculated for the zeta potential at the phase boundary in the pores.

5. Streaming potentials have been used to measure the equivalent pore radius, and a value of 4Å has been obtained.

6. It is concluded that electro‐osmosis is not responsible for fluid transfer by the intestine, and the potential difference associated with hexose transfer is not electrokinetic in origin.
Dexamethasone suppression of the plasma corticosterone response to stress in the rat
Authors: Donald R. A.
Published: December 2014

1. The effect of dexamethasone on the plasma corticosterone response to heat‐immobilization stress was investigated in male and female rats.

2. The plasma corticosterone response of control rats to the type of stress described was 64 μg% (± 10·5 μg% standard deviation) in males, and 128 μg% in females.

3. A straight line relation between the dose of dexamethasone and the log of the plasma corticosterone response was demonstrated in male rats. The slope of the dose—log response line was used to indicate the degree of suppression of the plasma corticosterone response to stress.

4. The straight line relation did not hold for female rats, suggesting the presence of an additional factor or factors which influenced the plasma corticosterone levels.

5. An exponential relation between the duration of dexamethasone administration and the slope of the dose—log response line was demonstrated, maximum suppression occurring after an infinite period of time. After 30 days, 95% maximum suppression occurred when the plasma corticosterone response was measured 8 hr after dexamethasone administration had ceased.
The reflex response to sinusoidal stretching of soleus in the decerebrate cat
Authors: Jansen J. K. S. , Rack P. M. H.
Published: December 2014

1. Soleus muscle in the decerebrate cat was stretched sinusoidally through various distances, at various frequencies while tension and e.m.g. activity were recorded.

2. Two patterns of stretch reflex activity were seen. In one, slow stretching led to a large increase in tension, whereas in the other tension increased little during slow stretching, but rose steeply during a more rapid stretch. Intermediate states were also seen.

3. Both these reflex patterns were abolished when the fusimotor fibres were blocked with Xylocaine.

4. At low frequencies of stretching the e.m.g. activity was greatest at peak muscle length; at higher frequencies the greatest activity was found during lengthening. This angular advance of e.m.g. activity on length was greatest at 3·3‐5 c/s. At the higher frequencies the e.m.g. activity was less in advance of muscle length.

5. Angular advance of e.m.g. activity was greatest in the preparations that were also the most sensitive to slow stretching.

6. Muscle contraction follows an electrical stimulus with a small delay. The delay between the end of stimulation and the end of muscle relaxation is longer, and may exceed 200 msec in cat soleus.

7. The timing of the reflex tension during sinusoidal stretching depended on how far the angular advance of the e.m.g. combined with the damping properties of muscle offset the time delays in the reflex pathway.

8. Changes in muscle tension generally preceded changes in muscle length. When, however, stretch amplitudes of 1 mm (peak to peak) were used, a phase delay of tension was sometimes seen. This only occurred in preparations that also showed little sensitivity to slow stretching.

9. Phase delay of tension was usually found with frequencies of approximately 6‐8 c/s, and this corresponds to the clonus frequency for soleus.

10. The mechanisms of the two types of reflex behaviour, and the damping properties of the system are discussed.
A rapid method for determining voltage‐concentration relations across membranes
Authors: Diamond Jared M.
Published: December 2014

1. A rapid method is described for obtaining curves relating the potential difference (p.d.) across a membrane to solute concentration gradients. The experiment consists of measuring the p.d. as a function of time while the concentration at the membrane is continuously increasing from 0 to Co (or decreasing from Co to 0) owing to diffusion through an unstirred layer.

2. The voltage trace is then analysed with a piece of transparent paper, on which lines corresponding to solutions of the diffusion equation convert the time axis of the voltage trace into a concentration axis. Superposition of this paper on an experimental voltage trace permits one to read off the p.d. corresponding to any concentration between 0 and Co.

3. The relation between diffusion potentials and NaCl concentration, and between streaming potentials and concentrations of impermeant non‐electrolytes, has been reconstructed by this procedure in rabbit gall‐bladder. The method yields non‐linear voltage—concentration curves in good agreement with those obtained by conventional methods, but requires much less time and experimental manipulation. The conditions that must exist for the method to be valid are discussed.

4. The thicknesses of the unstirred layers in rabbit gall‐bladder are measured, and are shown to have a negligible effect upon steady‐state streaming potentials and NaCl diffusion potentials.

5. The changes of permeability with osmolarity described in rabbit gall‐bladder must be complete within a fraction of a second, in agreement with the interpretation that they represent swelling and shrinking of the cell membrane itself.
Lingual mechanoreceptors activated by muscle twitch
Authors: Porter R.
Published: December 2014

1. Two groups of mechanoreceptors in the tongue have been identified by recording afferent discharges in single nerve fibres dissected from the lingual nerves of anaesthetized cats. The group of superficially situated, rapidly adapting mechanoreceptors had faster conduction velocities than the presumed deeply situated, slowly adapting endings.

2. Stretch of the tongue musculature did not prove to be as efficient in activating the endings as local deformation, although it was possible to excite some of the presumed deeply situated endings in this way.

3. No mechanoreceptor fibres could be identified in filaments dissected from the hypoglossal nerves in the same experiments.

4. Twitches of the tongue musculature produced by stimulation of the hypoglossal nerve were able to cause discharge of superficial and presumed deeply situated mechanoreceptors during the tension change.

5. The timing of the discharges in response to twitch was such that it could account for the delay in synaptic potentials produced in hypoglossal motoneurones when supramaximal stimuli were applied to the hypoglossal nerve.

6. The possible significance of mechanoreceptor discharges in reflex activation of tongue motor units is discussed.
The action of ketonic prostaglandins on the guinea‐pig myometrium
Authors: Clegg P. Catherine , Hall W. J. , Pickles V. R.
Published: December 2014

1. Prostaglandin E1 or E2 has two clearly distinguishable effects on the guinea‐pig myometrium in vitro.

2. The first of these, the ‘direct’ effect, is manifested by contraction accompanied by spiking, is readily modified by changes in the concentrations of Mg2+, Ca2+ and K+ in the suspension medium, and does not long outlast the presence of the prostaglandin in the organ‐bath. In this respect it resembles the responses to other stimulants.

3. The second effect is manifested by ‘enhancement’ of the responses to non‐specific stimulation, whether this be by chemical or electrical means. Enhancement may be demonstrated for up to 20‐80 min after the PGE1 or PGE2 has been washed out of the organ‐bath, and during this time the myometrium shows no consistent changes in electrical activity or in resting mechanical tension that may be associated with the enhancement effect. Enhancement following PGEs is not readily affected by moderate changes in the Mg2+, Ca2+ or K+ concentrations of the suspension medium, and in all these respects it differs markedly from the effects of other stimulants.

4. K+‐depolarized myometrial preparations show feeble direct responses to PGEs, like those to other stimulants. They also show post‐PGE enhancement of the responses to other stimulants, but not of the responses to electric field stimulation.

5. The empirical method used for measuring the enhancement effect is examined critically.

6. The possible mechanisms of the direct and enhancement effects are discussed. It is postulated that they involve actions at two different sites, which may be on two different types of cell but are more likely to co‐exist on the same cells. The direct effect is postulated to result from depolarization at the exposed cell membrane, whereas enhancement may result from facilitation of excitation—contraction coupling.
The localization of lysosomal enzymes in chromaffin tissue
Authors: Smith A. D. , Winkler H.
Published: December 2014

1. An homogenate of bovine adrenal medulla contains significant amounts of six acid hydrolases: acid ribonuclease, acid deoxyribonuclease, cathepsin, acid phosphatase, β‐glucuronidase and arylsulphatase. Most of the activity of each enzyme could be sedimented in the large‐granule fraction at 242,000 g‐min.

2. Differential centrifugation indicated the presence of three populations of particles, which sedimented at slightly different rates; these are, in order of decreasing sedimentation rate, mitochondria, particles containing the acid hydrolases, and chromaffin granules.

3. The three types of particle could be separated by ultracentrifuging the large‐granule fraction in a sucrose density gradient. Most of the activity of each hydrolase was recovered in a layer intermediate between those formed by mitochondria and chromaffin granules.

4. The large‐granule fraction therefore contains particles which are defined by their enzyme content as lysosomes.

5. Highly purified chromaffin granules, containing less than 5% of the activity of each acid hydrolase, were obtained from the gradient.
Organization of neurones in the cat cerebral cortex that are influenced from Group I muscle afferents
Authors: Oscarsson O. , Rosén I. , Sulg I.
Published: December 2014

1. Neurones in the Group I projection area of the first sensori‐motor cortex were investigated with extra‐ and intracellular technique.

2. The majority of the neurones influenced by volleys in Group I afferents of contralateral forelimb nerves received exclusively excitation, but some received exclusively inhibition, and some mixed excitation and inhibition.

3. The Group I influenced cells were usually found 500‐1500 μ beneath the cortical surface.

4. The EPSPs and IPSPs evoked from Group I afferents had a steep rising phase and a slow, approximately exponential decay. The duration was sometimes more than 50 msec. The EPSP evoked by a maximal Group I volley was often formed by a small number of large unitary EPSPs.

5. Latency measurements indicate that the majority of the Group I activated neurones were monosynaptically excited from the thalamic fibres, and hence constitute the fourth‐order neurones in the Group I projection system. The latencies of the IPSPs suggest a disynaptic linkage with thalamic fibres. Hence, the exclusively inhibited cells would constitute fifth‐order neurones. It is suggested that most or all of the fourth‐order neurones are inhibitory.

6. The convergence of excitation and/or inhibition to individual cells was usually extensive and included effects not only from muscle groups working at different joints but also effects from antagonistic groups at the same joint. In addition cutaneous afferents contributed synaptic actions which had a longer latency than the synaptic actions from Group I afferents.

7. The neurones influenced from Group I afferents were not antidromically activated on stimulation of the pyramidal tract.
Water diuresis in the domestic fowl
Authors: Dicker S. E. , Haslam J.
Published: December 2014

1. The exteriorization of ureters in domestic fowls allows the collection of urine uncontaminated by faeces.

2. When water is administered by stomach tube to a fowl, water is stored in the crop, from which it is slowly released into the proventriculus.

3. Immediately after water gavage, there is a sharp rise of urine flow accompanied by an increase in endogenous creatinine excretion and a fall in the osmolarity of the urine. This initial increase in urine flow is of short duration, and is followed by a normal curve of diuresis with a peak at about 90 min after hydration.

4. The first rise in urine flow following the filling of the crop appears to be of reflex origin, as distension of the crop with paraffin produces an enhanced excretion of urine and of creatinine.

5. Changes in urine flow and in creatinine excretion are closely correlated.

6. After water deprivation for 18 hr, the urine is slightly hyptertonic to blood. The maximum urine concentration observed was of the order of 600 m‐osmole/l.
Evidence that the secreting adrenal chromaffin cell releases catecholamines directly from ATP‐rich granules
Authors: Douglas W. W. , Poisner A. M.
Published: December 2014

1. Cats’ adrenal glands were perfused with Locke's solution and stimulated through the splanchnic nerves or by acetylcholine.

2. In response to such stimulation there appeared in the venous effluent, in addition to catecholamines, large amounts of AMP and adenosine and smaller amounts of ATP and ADP. Like the catecholamines, these substances had their origin in the chromaffin cells as was shown by their failure to appear when the splanchnic nerves were stimulated during perfusion with drugs blocking the adrenal synapses.

3. During stimulation the ratio of catecholamines: ATP and metabolites in the venous effluent corresponded closely with the reported ratio of catecholamines: adenine nucleotides in the ‘heavy’ chromaffin granules.

4. Adenine nucleotide appeared in the adrenal effluent pari passu with catecholamines within a second or two of beginning stimulation.

5. It is concluded that the nucleotide‐rich granules are the immediate source of catecholamines released from the stimulated adrenal chromaffin cell, and that the other two intracellular ‘pools’ that have been described, nucleotide‐poor and ‘free’ cytoplasmic catecholamines, contribute little or not at all.
Input organization of two symmetrical giant cells in the snail brain
Authors: Kandel E. R. , Tauc L.
Published: December 2014

1. The ventral surface of the snail brain contains two symmetrical giant cells which are readily identifiable in each preparation. These cells lie in the left and right metacerebrum, a cerebral integrative structure which makes afferent and efferent connexions with the periphery and with the infraoesophageal ganglia on each side by means of four ipsi‐ and four contralateral peripheral nerves and three ipsi‐ and three contralateral connectives.

2. In order to examine the functional consequences of this anatomical symmetry single or double micro‐electrodes, for intracellular recording and for direct stimulation, were placed in one or both of the ventral metacerebral giant cells.

3. Responses from 6 ipsi‐ and 6 contralateral inputs were examined for orthodromic and antidromic components. The results of these experiments revealed that the output organization (the pathways of the three axonal branches of the giant cells) as well as the input organization were completely symmetrical in the two cells. The anatomical symmetry therefore seems to have been functionally preserved. Simultaneous recordings from both cells failed to reveal direct interconnexions, but did show that the cells do share in common the output of at least two interneurones.

4. By recording from both cells it was also possible to demonstrate, for each of the symmetrical nerves and connectives, that laterality of an input was signalled by latency and by synaptic efficacy; the ipsilateral input produced EPSPs that were consistently more effective and of shorter latency than the contralateral ones.

5. Pharmacological studies revealed that both cells fall into the category called D cells by Tauc & Gerschenfeld (1961); they responded with depolarization to iontophoretic injection of ACh and all excitatory synaptic inputs were blocked by d‐tubocurarine.

6. With none of the twelve afferent inputs was synaptic inhibition observed. The results support the notion that D cells do not receive inhibitory input.
The mechanism of insulin action. The effect of insulin on the allosteric properties of intracellular haemoglobin
Authors: Dormandy T. L.
Published: December 2014

1. The results in three experimental series have suggested that a number of modifying factors must be taken into account in considering the allosteric behaviour of structurally bound intracellular, as distinct from free, haemoglobin. It seems that intracellular haemoglobin maintains its maximal internal stability during oxygen uptake and release by configurational changes which involve not only its acid—base‐binding groups but also partial electron‐transfer complexes with the stromal macro‐molecular framework. Conversely, the affinity of intracellular haemoglobin for oxygen reflects the positive or negative electron pressures prevailing at the haemoglobin‐stromal complexing sites.

2. Active glucolysis in intact cells entails continuous poising of metabolic redox potential changes by the stromal material (in the same way as it entails continuous buffering of acid metabolic products). The consequent shifts in stromal redox potential and capacity are transmitted to haemoglobin and are reflected in a changing affinity for oxygen.

3. The behaviour of the intracellular haemoglobin‐stromal complex is further modified by extracellular electron donors and acceptors and by the capacity of the cell/extracellular interface to act as an electrochemical barrier between them. It is probably the last variable which is directly influenced by insulin.

4. Two parameters have been introduced as empirical measures of the distinctive allosteric properties of cell‐bound haemoglobin: (i) D—pH to represent the apparent cell/extracellular pH gradient; and (ii) D—O2 to represent the volume of oxygen evolved when cells are lysed at a constant PO2. Under a variety of experimental conditions insulin affected both these parameters.

5. The insulin effects were consistent with a concept which rests on three main contentions. (i) Insulin has an immediate physical action on the cell/extracellular interface, altering the redox potential gradient (electron conductance) across the plasma membrane. (ii) Conversely, the formation of an insulin‐membrane complex depends, among other factors, on the prevailing trans‐membrane redox potential difference. (iii) The consequences of insulin‐membrane interaction are both immediate and sustained, and, under appropriate conditions, they are reflected in the affinity of intracellular haemoglobin for oxygen.

6. At a more general level it has been shown that in many respects haemoglobin behaves as a built‐in intracellular redox indicator dye. Like most synthetic redox indicators, it is pH dependent.
The relation between sarcomere length and active tension in isolated semitendinosus fibres of the frog
Authors: Edman K. A. P.
Published: December 2014

1. The relation between sarcomere length and tetanic tension at various states of shortening was investigated in single frog semitendinosus fibres that were subjected to different degrees of prestretch (2·45‐3·0 μ).

2. The capacity to produce tension changed in a characteristic way during shortening, the tension output at each length being determined by the actual sarcomere spacing without reference to the striation spacing at the onset of contraction.

3. The capacity to shorten against a given load was independent of the initial striation spacing, provided the load was not great enough to cause fatigue of the fibre.

4. The findings strongly suggest that the functionally relevant structure of the contractile system of the intact muscle cell is always in the same state at a given sarcomere length independent of how the previous length change has been achieved, by passive extension at rest or by active shortening from a prestretched position. This probably means that contraction involves a structural change of the contractile system, which, at least in so far as it is of relevance to function, is a true reversal of the change produced by passive extension of the resting fibre. These aspects of the contractile behaviour of the intact muscle fibre are in full accord with the concepts of the sliding‐filament hypothesis of muscular contraction.
The distribution of cholinesterases in the cat carotid body
Authors: Biscoe T. J. , Silver Ann
Published: December 2014

1. The distribution of acetyl‐ and butyrylcholinesterase in the carotid body of the cat has been examined histochemically. Studies were made on normal carotid bodies and on carotid bodies from cats in which certain nerves had been cut some time previously. The nerves sectioned were the sinus nerve, the post‐ganglionic sympathetic branch of the superior cervical ganglion or the preganglionic cervical sympathetic trunk.

2. It was confirmed that more butyrylcholinesterase than acetylcholinesterase is present. Both enzymes are found in three sites: (i) as strands, (ii) as plexuses, (iii) inside a few cells.

3. The distribution is unaffected by cutting the sinus nerve or preganglionic cervical sympathetic nerves. Disorganization and depletion of the cholinesterases in the strands and plexuses occurs when the post‐ganglionic branch of the superior cervical ganglion is cut. The cholinesterase in cells is unaffected.

4. In carotid bodies in which vessels were filled with red blood cells or in which the vascular bed was injected with carmine‐gelatine, it was seen that strands and plexuses are associated with blood vessels, and with blood vessels and cells respectively.

5. It is suggested that a cholinergic pathway controlling carotid body blood vessels runs in the post‐ganglionic cervical sympathetic.
The distribution of ions in the smooth muscle of the guinea‐pig taenia coli
Authors: Buck B. , Goodford P. J.
Published: December 2014

1. Tracer movements and ionic composition have been observed in the smooth muscle of the guinea‐pig taenia coli in vitro at 4, and 35° C. The muscle was quiescent at 4° C, and did not show spontaneous electrical nor mechanical activity for 25 min after re‐warming. It was therefore possible to make observations on the quiescent tissue at 35° C.

2. The rate of loss of tracer sodium was sensitive to changes of temperature, with an average Q10 of 3·4 ± 0·4 on warming in the range 4‐35° C. Exponential analysis of 24Na efflux at 35° C showed an initial rapid phase, a second phase with t½ = 2 min, and a slowly exchanging phase. The second phase was most sensitive to changes of temperature and contained 15 m‐mole Na/kg fresh wt. The corresponding transmembrane flux in spontaneously active muscle at 35° C would then be 30 p‐mole cm−2 sec−1, and 20% of the available metabolic energy would be needed to maintain this exchange.

3. The rate of loss of tracer sodium was reduced in potassium‐free or sodium‐free solutions, but the effects were not impressive.

4. The cell size increased at 4° C, and fell again on warming while Na and Cl left the cell and K was taken up. Cell chloride content was linearly related to cell size.

5. The observations are interpreted on the assumption that the cytoplasm is osmotically isotonic and electrically neutral, and that some Na, K and Cl are sequestered elsewhere in the tissue. It is concluded that the quiescent smooth‐muscle cell membrane is rather more permeable to sodium than the skeletal‐muscle cell membrane.
The interrelation of thermoregulatory and baroreceptor reflexes in the control of the blood vessels in the human forearm
Authors: Crossley R. J. , Greenfield A. D. M. , Plassaras G. C. , Stephens Dorothy
Published: December 2014

1. The interrelation of thermoregulatory and baroreceptor reflexes in the control of the circulation through the forearm has been investigated in eight men.

2. The results are compatible with the current hypotheses that thermoregulatory reflexes employ exclusively blood vessels in the skin, and that baroreceptor vasodilator reflexes excited by transfer of blood from the legs to the trunk employ exclusively blood vessels in the muscles. They are compatible with the hypothesis that baroreceptor vasoconstrictor reflexes excited by transfer of blood from the trunk to the legs employ blood vessels in muscles, but not with the hypothesis that they do so exclusively.

3. The results indicate that when blood is transferred from the trunk to the legs, vasoconstriction over‐rides thermoregulatory vasodilatation, presumably in the blood vessels of the skin.

4. The circulation through the skin appears, therefore, to be under baroreceptor as well as thermoregulatory reflex control, and over the short period of time examined, namely 1 min, the baroreceptor control takes precedence.
Time course and nature of temperature‐induced changes in sodium‐glucose interactions of the goldfish intestine
Authors: Smith M. W.
Published: December 2014

1. Glucose‐evoked potentials measured at low incubation temperatures were found to be highly temperature dependent (phase 1), but less so at high incubation temperatures (phase 2) and acclimatization of an 8°C fish to 25° C resulted in the extension of phase 1 up to the environmental temperature of the fish. This change was only part of the mechanism controlling the acclimatization of sodium transport across the intestine.

2. The temperature at which the glucose‐evoked potential changed from phase 1 to phase 2 was approximately equal to the temperature at which glucose began to raise the steady transmural potential of the intestine.

3. No changes in intestinal electrical parameters could be detected when fish, acclimatized to 8° C, were heated at 25° C for 15 hr, but after 20 hr at the higher temperature, acclimatization to the new temperature was complete.

4. Intestines from fish acclimatized to 8° C, but which had first spent 15 hr at 25° C and then 10 hr at 8° C, still behaved qualitatively like 8° C — intestines but the magnitude of the glucose‐evoked potentials was slightly reduced.

5. It is suggested as a working hypothesis that acclimatization of the sodium‐glucose interaction to different environmental temperatures involves the synthesis of new carrier molecules, qualitatively different from the old ones.
The characteristics of spontaneous and evoked action potentials recorded from the rabbit's uterine nerves
Authors: Bower E. A.
Published: December 2014

1. A method is described for recording in vivo the action potentials of afferent and efferent fibres in whole nerves supplying the rabbit's uterus.

2. Examination of these nerves under the light microscope and the electron microscope showed them to be composed almost entirely of non‐myelinated fibres.

3. Two types of spontaneous action potential were observed; one travelled at about 4 m/sec and probably came from the myelinated fibres, the other travelled at 0·4‐1·4 m/sec and certainly came from non‐myelinated fibres.

4. The efferent fibre spikes were shown to be faster and higher than the spikes from uterine afferent fibres, but slower and smaller than spikes from broad ligament afferent fibres.

5. Apart from differences in conduction velocity and height, all spikes were basically similar, lasting about 1·5 msec. The height was related to the square of the velocity. Some more complex spikes were also observed.

6. The compound action potential evoked by stimulation of the uterine nerve had three peaks, conducted at 1·3, 0·8 and 0·6 m/sec, respectively, and thought to correspond to the fast afferent fibres, the efferent fibres and the slow afferent fibres, respectively. There were also some late peaks due to reflexion of the antidromic action potentials from the ganglion cells.

7. Stimulation of the hypogastric nerve also evoked a compound action potential in the uterine nerves. Stimulation of the pelvic nerves had no effect.

8. By means of ganglion blocking agents, the uterine ganglia were shown to lie in the pelvic plexus, peripheral to the hypogastric nerve, but central to the uterine nerves.

9. It is argued that the spontaneous action potentials came from individual fibres rather than Remak bundles, and that the recording technique used detected the activity of all but the smallest fibres.
Intracellular and extracellular compartments of mammalian central nervous tissue*
Authors: Ames A. , Nesbett Frances B.
Published: December 2014

1. Isolated rabbit retina was used as a prototype of grey matter to study the partition of water and electrolytes between the intracellular and extracellular phase. Previously published morphologic, chemical, and functional evidence has shown that it can be maintained in vitro in a nearly physiological state.

2. Following equilibration with mannitol or inulin, retinas were eluted in isotonic tris acetate at 0° C, and measurements were made of the rates at which K+, Na+, Cl− and inulin or mannitol diffused from the tissue.

3. K+ was eluted slowly according to a single exponential decay. The Na+ and Cl− elution curves demonstrated two phases which could be dissected into a rapid, multicomponent regression superimposed upon a slow exponential decrease.

4. The volume of distribution of the readily elutable Na+ equalled that of the readily elutable Cl− and corresponded closely to the volume of distribution of mannitol and inulin. On the basis of these and previously published data, the interstitial fluid was estimated to constitute 31% (w/w) of rabbit retina and 22% of rabbit brain.

5. The composition of the extracellular fluid of retina resembled closely that of the medium in which the tissue had been previously incubated.

6. Inulin, mannitol, and NaCl diffused through the less accessible portions of the extracellular space at rates which differed from one another as predicted from the diffusion coefficients of these solutes. Their diffusion through the more accessible portions of the extracellular space was apparently affected by bulk flow of the fluid.

7. The intracellular concentrations of K+, Na+, and Cl− were estimated to be 148, 31, and 17 m
M respectively.

8. Na+ and K+ moved across the cell membranes at almost precisely the same rate under the conditions of the elution.
An investigation of the post‐tetanic potentiation of end‐plate potentials at a mammalian neuromuscular junction
Authors: Gage P. W. , Hubbard J. I.
Published: December 2014

1. End‐plate potentials (e.p.p.s) were recorded intracellularly from neuromuscular junctions in curarized or Mg‐paralysed rat diaphragm‐phrenic nerve preparations in vitro. In Mg‐paralysed preparations after 1000 impulses at 100/sec the amplitude of e.p.p.s elicited at 1/sec before and after the tetanus was on average greater than the control amplitude for 120 ± 30 sec.

2. The post‐tetanic potentiation (
P.T.P.) of e.p.p. amplitudes was not thought to be dependent upon post‐tetanic hyperpolarization (
P.T.H.) of nerve terminals as it lasted longer than the hyperpolarization generated by an identical tetanus; was unaffected by hyperpolarizing currents which reduced
P.T.H. or depolarizing currents which prolonged
P.T.H.; and was diminished in solutions containing 30% of the normal NaCl concentration or 1% ethyl alcohol, both of which procedures prolong
P.T.H. The magnitude and duration of
P.T.P. were influenced by the pH of the bathing solution in the range 7‐7·5 although there was no change in
P.T.H. under these conditions. The inability of polarizing currents to influence
P.T.P. was also thought inconsistent with the hypothesis that
P.T.P. is due to an increase in available transmitter.

3.
P.T.P. was not thought to be due to sodium accumulation in nerve terminals, for
P.T.P. was reduced or abolished by procedures which would be expected to increase the intraterminal sodium ion concentration. These procedures were: exhibition of metabolic inhibitors (1·8 × 10−6
M antimycin A, 3‐5 m
M sodium azide or 1 m
M sodium iodoacetate), exhibition of cardiac glycosides (7·7 × 10−6
M digoxin or 0·42 m
M ouabain), and omission of glucose or potassium ions from the bathing solution. Abolition of
P.T.P. by potassium‐free solutions was also thought to be inconsistent with the hypothesis that
P.T.P. is due to a reduction in the potassium concentration in nerve terminals.

4.
P.T.P. was not thought to be due to terminal volume changes, for no consistent effect upon the quantal content of e.p.p.s could be detected in hypo‐ or hyperosmotic solutions.

5. It was concluded that the only hypothesis for
P.T.P. not excluded by our experiments was that
P.T.P. is due to some change in ionized calcium at a membrane site important in transmitter release.
Blocking of the impulse and depression of the receptor potential by tetrodotoxin in non‐myelinated nerve terminals in pacinian corpuscles
Authors: Nishi K. , Sato M.
Published: December 2014

1. The effect of tetrodotoxin on the impulse and the receptor potential of the non‐myelinated nerve terminal in Pacinian corpuscles has been investigated.

2. Tetrodotoxin at a concentration of 1 × 10−7 g/ml. raises the threshold for initiating an impulse at the terminal. 5 × 10−7 g/ml. tetrodotoxin blocks the initiation of impulses.

3. The receptor potential magnitude is reduced to about 60% of the control value by 5 × 10−7 g/ml. tetrodotoxin within 30‐60 min and maintains this value for a logn time. The amount of the maximum reduction in the receptor potential by 1 × 10−6 and 2 × 10−6 g/ml. tetrodotoxin is not significantly greater than the one by 5 × 10−7 g/ml. tetrodotoxin.

4. No difference in the time constant of the falling phase of the receptor potential was found before and after application of tetrodotoxin.

5. The mechanism underlying the generation of the receptor potential has been discussed and the difference of its mechanism from the one concerned with the junctional potential pointed out.
Calcium metabolism in normal and thyro‐parathyroidectomized goats
Authors: Payne J. M. , Sansom B. F.
Published: December 2014

1. The effects of thyro‐parathyroidectomy on calcium metabolism in the goat have been investigated using stable calcium balance techniques and the isotopes 45Ca, 47Ca and 85Sr.

2. Thyro‐parathyroidectomized goats, whether receiving supplementary thyroxine or not, are in negative calcium balance, whereas normal or thyroidectomized animals are in positive balance.

3. Gastro‐intestinal absorption of 45Ca is less in thyro‐parathyroidectomized goats, whether receiving supplementary thyroxine or not, than in either normal goats or thyroidectomized goats receiving thyroxine supplements.

4. The rate of endogenous secretion of calcium into the gastro‐intestinal tract is unchanged by either thyroidectomy or thyro‐parathyroidectomy. Urinary excretion of calcium is also apparently unchanged.

5. The bone calcium accretion rate is reduced to approximately the same extent in thyroidectomized and thyro‐parathyroidectomized goats. Thyroxine supplements restore the bone accretion rate of both groups of animals to normal or greater than normal levels.

6. The bone calcium resorption rate is greater in thyro‐parathyroidectomized goats, whether receiving thyroxine supplements or not, than in either normal goats or thyroidectomized goats receiving thyroxine supplements.