bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrical and mechanical response of arteries to stimulation of sympathetic nerves
Authors: Keatinge W. R.
Published: December 2014

1. When common carotid arteries of sheep were studied in vitro by the sucrose‐gap method, application of acetylcholine or nicotine caused small irregular spikes of depolarization. The discharge was prevented by hexamethonium, Hydergine, phentolamine, or chronic denervation, indicating that it represented electrical activity of groups of smooth muscle cells induced by the stimulation of sympathetic nerve fibres.

2. The size of spikes produced by acetylcholine or nicotine, together with counts of the total number of smooth muscle cells in cross‐sections of the arterial strips, indicated that the larger groups of smooth muscle cells activated by one sympathetic nerve fibre contained approximately 1300 cells.

3. Sections of arteries treated with hot formaldehyde vapour contained numerous fluorescent fibres which were intensified by previous injection of noradrenaline into the animal and were scanty or absent after chronic sympathetic denervation. They are therefore believed to be post‐ganglionic sympathetic nerve fibres.

4. Most of these fibres ran circularly in the outer ½‐¾ of the media. A few ran longitudinally in the adventitia. There were none in the inner ¼‐½ of the media.

5. Electrical stimulation of the cervical sympathetic nerve of anaesthetized sheep caused large contractions of the common carotid artery of the same side, reducing its external diameter by 30‐39%.
Action potentials in parasympathetic and sympathetic efferent fibres to the trachea and lungs of dogs and cats
Authors: Widdicombe J. G.
Published: December 2014

1. Action potentials were recorded from seventy‐four single and twenty‐nine small multifibre nerve strands efferent to the trachea and lungs of cats and dogs. From the pathway (vagal or sympathetic), spontaneous activity, conduction velocity and responses to various interventions the efferent fibres were classified in the following way.

2. Group I, vagal. These had a mean conduction velocity of 9·7 m/sec, and had a respiratory but seldom a cardiac rhythm. Their discharge was inhibited during hypertension caused by injections of adrenaline and during inflation of the lungs, but was increased during tracheal occlusion, stimulation of peripheral chemoreceptors and irritation of the larynx. The fibres are thought to be constrictor to the airways.

3. Group II, sympathetic. These had a mean conduction velocity of 0·85 m/sec and usually had inspiratory and cardiac rhythms. Their discharge usually responded qualitatively as that of group I fibres to the various interventions, but with clear quantitative differences. They are divided into three subgroups on the basis of their responses to injections of adrenaline and to asphyxial stimuli.

4. Group III, vagal and sympathetic. These had a mean conduction velocity of 9·0 m/sec, very slow discharge rates and often an expiratory and cardiac modulation. They were activated during hypertension due to adrenaline and often by tracheal occlusion, chemoreceptor stimulation, laryngeal irritation and lung inflation. Their motor action is unknown.

5. Group IV, vagal and sympathetic. These had conspicuous cardiac rhythms resembling those of vascular baroreceptors, but their discharge could not be correlated with arterial blood pressure. Their mean conduction velocity was 6·6 m/sec. Some were active after combined vagotomy and sympathectomy. Together with some unclassified fibres, those of group IV are thought to be aberrant afferent nerves or collateral afferent branches, and possibly to subserve local reflexes.

6. The results are discussed in relation to nervous control of effector tissues in the airways and autonomic nervous control generally.
The effect of oligomycin and some nitrophenols on acid secretion and oxygen uptake by gastric mucosa of the frog
Authors: Bannister W. H.
Published: December 2014

1. The ability of the three nitrophenols, m‐nitrophenol, p‐nitrophenol and 2,4‐dinitrophenol, to inhibit acid secretion and stimulate oxygen uptake by gastric mucosa paralleled their extent of dissociation at physiological pH.

2. Oligomycin inhibited oxygen uptake by gastric mucosa, and showed a tendency to inhibit acid secretion.

3. 2,4‐dinitrophenol lowered the value of the ratio between acid secretion and the associated oxygen uptake. Oligomycin did not affect the value of this ratio.

4. It would appear that a non‐phosphorylated high‐energy intermediate of oxidative phosphorylation might be involved in acid secretion by gastric mucosa.
Polarized light and the human fundus oculi
Authors: Weale R. A.
Published: December 2014

1. Measurements were made of the relative fractions of diffuse and specular reflexions in the fovea and periphery of the human fundus oculi.

2. All the light emerging from the eye is scattered or reflected behind the receptors as bleaching the retina affects both fractions equally.

3. Bruch's membrane is the most likely surface at which specular reflexion occurs whereas the choroid and sclera are probably involved in scattering.

4. Both diffuse and specular components show marked directional effects that vary with wave‐length.
Active transport of sodium and potassium in mammalian skeletal muscle and its modification by nerve and by cholinergic and adrenergic agents
Authors: Dockry Margaret , Kernan R. P. , Tangney Aileen
Published: December 2014

1. Active transport of Na+ and K+ by Na‐rich extensor digitorum and soleus muscles of rat was found to be increased considerably when muscles were innervated during enrichment with Na+ in K‐free modified Krebs solution containing 160 m
M‐Na at 2° C and recovery in a similar fluid with 10 m
M‐K and 137 m
M‐Na at 37° C, bubbled with oxygen.

2. Addition of acetylcholine (2·0 μg/ml.) to recovery fluid containing denervated extensors increased active transport, whereas addition of eserine (50 μg/ml.), decamethonium (0·1 μg/ml.) and to a lesser extent tubocurarine (0·26 μg/ml.) inhibited active transport. Blocking of nerve conduction in innervated extensor inhibited K+ uptake more than Na+ excretion.

3. The membrane potential of Na‐rich extensor muscles measured soon after re‐immersion in recovery fluid was higher in denervated than in innervated muscles. In the latter it was close to the K‐equilibrium potential (EK). It is suggested that denervation here makes the Na‐pump electrogenic by decreasing K+ uptake either by decreased permeability or by inactivating a K‐pump. Evidence is presented that the latter is more likely.

4. Addition of isoprenaline to Na‐rich soleus muscles in recovery fluid increased active transport and reduced the membrane potential measured soon after re‐immersion in recovery fluid. The Na‐pump still remained electrogenic in the presence of isoprenaline. It was suggested that isoprenaline might also stimulate the Na‐pump, perhaps through activation of lactic dehydrogenase.
Cardiovascular and metabolic responses to noradrenaline in man, before and after acclimatization to cold in Antarctica
Authors: Budd G. M. , Warhaft N.
Published: December 2014

1. Four men of European descent were infused with noradrenaline at rates of 0·038, 0·075, 0·150 and 0·300 μg/kg.min in Australia, and again after 29 weeks' residence at Mawson, Antarctica. A concurrent study of their responses to whole‐body cooling showed that they acclimatized to cold in Antarctica.

2. Blood pressure rose and heart rate fell in proportion to the dose of noradrenaline infused. The response was much less after than before acclimatization in three of the four subjects. Subjective effects of the drug decreased in proportion to the decrease in the pressor effect.

3. Finger temperature fell in proportion to the dose infused, in three subjects. The response was unchanged or increased after acclimatization.

4. Oxygen consumption was initially unaffected by noradrenaline, but after acclimatization it apparently increased in proportion to the dose infused. The increase in pulmonary ventilation during infusion was slightly greater after acclimatization.
The effect of the replacement of calcium by strontium on excitation‐contraction coupling in frog skeletal muscle
Authors: Edwards Charles , Lorković Hrvoje , Weber Annemarie
Published: December 2014

1. In frog skeletal muscle strontium can replace calcium in potassium contractures for 5 hr, though it is less effective than Ca. Sr can restore the responsiveness to K after it had been lost in the presence of Mn.

2. Muscles refractory to caffeine following repeated exposure to it in the absence of Ca, recover in part following addition of Sr.

3. The uptake of 85Sr was increased during mechanical activity, whereas the uptake of 58Co was not changed. Resting uptake of 58Co was 3‐4 times greater than that of 85Sr.

4. Sr fully activated the myofibrillar adenosine triphosphatase (ATP‐ase), though its affinity was about 30 times less than Ca.

5. The sarcoplasmic reticulum took up Sr, though less effectively than Ca.
The use of labelled vitamin B12 in the measurement of glomerular filtration rate
Authors: Ekins R. P. , Nashat F. S. , Portal R. W. , Sgherzi A. M.
Published: December 2014

1. Two preparations of radioactive vitamin B12 labelled respectively with 57Co and 58Co have been employed in the estimation of the glomerular filtration rate (
G.F.R.) in dogs. The intravenous injection of these preparations at an interval of 20 min resulted in a changing ratio of their activities in plasma and urine and so permitted a relation in time to be established between the urine and the plasma from which it was filtered.

2. When urine and plasma were sampled at short intervals an effective renal delay or transit time could be derived from their isotope ratio curves and used as a correction in the clearance equation. This allowed serial clearances of either isotope to be calculated despite a falling plasma concentration.

3. This method was applied to the study of the
G.F.R. in fourteen dogs using short urine collections of 2 or 4 min for periods up to 80 min. The results under stable conditions and with deliberately induced changes in the
G.F.R. are illustrated and discussed.

4. Application of the technique in four patients undergoing differential renal function studies gave results comparable with those in the experimental work.

5. The plasma binding of administered vitamin B12 in serial blood samples in dogs and man was investigated.
The effects of ventilation of dogs with different gas mixtures on airway calibre and lung mechanics
Authors: Green M. , Widdicombe J. G.
Published: December 2014

1. Dead space (CO2‐front method), lung compliance, cervical tracheal volume change and total lung resistance were measured simultaneously in anaesthetized dogs, paralysed or open‐chest, and the responses to nerve section and stimulation and to ventilation of the dogs with different gas mixtures were studied.

2. Bilateral cervical vagotomy changed all four parameters in a way consistent with airway dilation, and bilateral vagal stimulation had the opposite actions. A weak airway dilator role was indicated for the sympathetic nerves.

3. Ventilation with 4% CO2, 8% CO2 or 10% O2 changed all four parameters as if the airways had constricted, and 100% O2 caused oppossite, but weaker, responses.

4. The responses to the three airway constricting gas mixtures were present, but reduced in intensity, after bilateral cervical vagotomy and some even weaker responses were present after additional bilateral sympathectomy.

5. During restoration of airway smooth muscle tone by electrical stimulation of the distal ends of the cut vagus nerves, administration of CO2‐rich or hypoxic gas mixtures had no greater effect than during controls with vagi cut but without stimulation.

6. No dilator responses to hypercapnia or hypoxia were seen, either in innervated or denervated trachea and airways.
Micro‐electrode studies on mammalian vascular muscle
Authors: Steedman Wilma M.
Published: December 2014

1. Transmembrane potentials were measured in smooth muscle cells in the walls of small arteries in the frog tongue and skin of the lateral abdomen. Resting potentials had mean values of 64·7 and 43·6 mV respectively, and action potentials of up to 60 mV amplitude and 100‐200 msec duration could be elicited by electrical stimulation in the tongue vessels.

2. Micro‐electrodes were inserted into smooth muscle cells in the walls of small arteries and arterioles of the rat mesenteric circulation. Intracellular potentials varied continually and maximum polarization averaged 39·4 mV.

3. Rhythmic slow waves with a period varying from 4·5 to 7·8 sec were observed, and their amplitude but not their frequency was affected by the level of anaesthesia.

4. Spike potentials were recorded, amplitude up to 35 mV, with occasional overshoot, and duration 40‐50 msec; these were followed by a positive after‐potential, 100‐150 msec duration and amplitude up to 8 mV.

5. Experiments using chemical and surgical means of interfering with the autonomic nervous system showed that the amplitude, but not the frequency, of the slow waves and the occurrence of action potentials were markedly affected by nervous influences.

6. Stimulation of the smooth muscle by asphyxia, electrical stimulation of the splanchnic nerves, and local application of adrenaline, noradrenaline and vasopressin increased the frequency of action potentials and the amplitude of the slow waves, and inhibiting agents such as acetylcholine and removal of the nerve supply depressed the electrical activity.
Radioisotopic studies of the binding, exchange, and distribution of 5‐hydroxytryptamine synthesized from its radioactivity precursor
Authors: Gershon M. D. , Ross L. L.
Published: December 2014

1. The synthesis, distribution, storage, and subsequent metabolism of 5‐hydroxytryptamine (5‐HT) produced in mice from the administration of its radioactive precursor, 5‐hydroxytryptophan, has been investigated to form the basis for a similar study to be conducted by radioautography.

2. Intravenous injection of the radioactive material was found to be essential for significant uptake of radioactivity by tissue. The duration of the period during which radioactive material was available for uptake by the tissue was 2 hr.

3. The relative distribution of radioactivity in individual organs was studied and the radioactive compounds present in each were identified and quantitatively assayed. No unrelated routes of metabolism of the labelled material were found and radioautographic results may be interpreted in terms of the metabolic picture which emerged.

4. Radioactive 5‐HT was bound in tissues in preference to both its precursor, and metabolite, 5‐hydroxytryptamine‐O‐glucuronide, and the radioactive 5‐HT produced in vivo after the injection of labelled 5‐hydroxytryptophan probably entered and labelled the endogenous 5‐HT pool.

5. Fixatives prepared with buffer solutions made hypertonic by the addition of sucrose could rapidly and effectively halt the movement of radioactive 5‐HT out of tissues and prevent its subsequent extraction during histological processing.

6. It is concluded that localization of sites concerned with 5‐HT metabolism by means of radioautography is feasible and the 5‐HT so localized will probably reflect the physiological compartmentalization of the amine.
Uterine distension and the function of the corpora lutea in the guinea‐pig
Authors: Bland K. P. , Donovan B. T.
Published: December 2014

1. The presence of two glass beads (7 × 3 mm) in each horn of the uterus was associated with a reduction of 3‐4 days in the length of the oestrous cycle.

2. Two beads inserted into each uterine horn between days 2 and 4 exerted a greater effect on the oestrous cycle than either one bead in each horn or four beads in one horn only. Two beads located in one horn failed to affect cycle length.

3. Measurement of the volume of the corpora lutea showed that distension of the uterus induced a premature regression in the size of the luteal bodies.

4. When glass beads were present in one uterine horn, early and unilateral regression of the corpora lutea in the ovary adjacent to the distended horn was observed. Regression of the corpora lutea in the opposite ovary proceeded normally.

5. In view of the local effect of uterine distension and other information, it is concluded that each uterine horn can produce a luteolytic substance which is conveyed to the neighbouring ovary to act upon the corpora lutea.
The volume of vascular compartment in rat hind limb muscles
Authors: Law R. O. , Phelps C. F.
Published: December 2014

1. A non‐recirculatory perfusion system has been developed suitable for the perfusion of the hind limbs of small experimental animals.

2. By means of it a solution of T. 1824‐labelled serum albumin has been introduced into the vascular compartment of the hind limbs of female rats under isogravimetric conditions. Excision and analysis of certain muscles has been used to provide information concerning the percentage distribution of the labelled albumin within these muscles.

3. Experiments have been carried out in vivo employing [131I]labelled serum albumin and [51Cr]labelled erythrocytes in order to compare the vascular volumes determined under in vivo conditions and in perfusions, and to estimate the capillary haematocrit in vivo.

4. The physiological validity of the methods used and the results obtained has been discussed.
The size of the sucrose, raffinose, and inulin spaces in the gastrocnemius muscle in the rat
Authors: Law R. O. , Phelps C. F.
Published: December 2014

1. The sucrose, raffinose and inulin spaces within the gastrocnemius of the female rat have been estimated at 12·0 ± 2·2%, 10·7 ± 0·6%, and 10·0 ± 0·3% respectively, expressed as a percentage of the total muscle volume.

2. The mucopolysaccharide and hexosamine contents of the gastrocnemius have been found to be inversely dependent upon the weight of the muscle.

3. The possibility that a relation exists between the saccharide spaces and the muscle musopolysaccharide content has been discussed in terms of saccharide molecular radii.
The effects of adrenaline and noradrenaline on venous return and regional blood flows in the anaesthetized cat with special reference to intestinal blood flow
Authors: Greenway C. V. , Lawson Anne E.
Published: December 2014

1. In cats, a venous long‐circuit technique was used to measure the blood flows in the superior vena cava and the hepatic, renal and iliac segments of the inferior vena cava. The sum of these flows gave the venous return (minus coronary and bronchial flows). In further experiments using an electromagnetic flowmeter, flow in the portal vein and in the superior mesenteric and coeliac arteries was measured.

2. Approximately two‐thirds of the hepatic blood flow is derived from the portal vein.

3. After block of conduction in the cervical region of the spinal cord, the proportions of the venous return coming from each region during the control periods were not significantly altered although the arterial pressure and total venous return were decreased.

4. Intravenous infusions of adrenaline caused an increase in venous return which was associated with a marked increase in hepatic blood flow. The increase in hepatic blood flow was due to an increase in flow in the superior mesenteric artery and portal vein. Flow in the coeliac artery remained unchanged. This response was unaffected by block of the cervical region of the spinal cord and by atropine or pentolinium.

5. Intravenous infusions of noradrenaline caused little change in venous return or regional blood flows. Small increases in superior mesenteric artery flow were occasionally seen and on cessation of the infusion a large but brief increase occurred. These facts suggest that noradrenaline has a similar action to adrenaline but this is masked by concomitant vasoconstriction.
The time and voltage dependence of the slow outward current in cardiac Purkinje fibres
Authors: McAllister R. E. , Noble D.
Published: December 2014

1. In normal Tyrode solution the initial inward sodium current which is produced in Purkinje fibres in response to a sudden depolarization is followed by a very slow change in current in an outward direction. The magnitude and speed of onset of this slow change both increase with the strength of the depolarization.

2. On repolarization, a transient outward current is observed (Deck & Trautwein, 1964). The initial magnitude of this outward current also increases with the strength and duration of the preceding depolarization, with a time course similar to the time course of the slow change in current during depolarization.

3. Evidence is presented for the view that the slow change in current during depolarization represents the onset of delayed potassium rectification and that the decline in outward current following repolarization represents its decay.

4. Removal of sodium ions greatly increases the threshold of the slow outward current. In the presence of sodium ions 15 mV depolarization is sufficient to produce an appreciable current. In the absence of sodium ions at least 50 mV depolarization is required and, in some fibres, no delayed rectification is observed even when the membrane potential is made positive.

5. Prolonged depolarization of the membrane by outward current changes the quiescent membrane potential in a positive direction. This change in potential is attributed to an accumulation of potassium ions in a space immediately outside the cell membrane, which equilibrates slowly with the extracellular fluid. It is shown that this effect is very small during depolarizations of the magnitude and duration of the normal action potential.

6. It is concluded that the results are consistent with the view that repolarization of the Purkinje fibre action potential is initiated by a slow increase in K conductance similar to, but much smaller and slower than, that observed in nerve fibres.
The effects of suxamethonium and acetylcholine on the behaviour of cat muscle spindles during dynamic stretching, and during fusimotor stimulation
Authors: Rack P. M. H. , Westbury D. R.
Published: December 2014

1. The responses of primary and secondary afferent fibres from muscle spindles in cat soleus were studied during constant velocity stretching.

2. Intravenous Suxamethonium (SCh) caused a large increase in the response of the primary afferents to the dynamic phase of stretching, and a smaller increase in their response to static extension. The effects of SCh were similar to the effects of dynamic fusimotor stimulation.

3. Increasing doses of SCh increased the response of primary afferents to dynamic stretching up to a point, but a peak discharge frequency was encountered beyond which the afferent fibre could not be induced to discharge.

4. Suxamethonium increased the response of the secondary afferent fibres by a smaller amount than the primaries, and in particular caused a smaller increase in the response to dynamic extension.

5. Acetylcholine given by close arterial injection had an effect similar to the effect of SCh.

6. The effects of static and dynamic fusimotor stimulation on the response of primary afferents summed with the effects of small doses of SCh. When large amounts of SCh were used fusimotor stimulation sometimes had no further effect on the afferent discharge. It was not possible to say whether the fusimotor activity was then inhibited, or submerged in the SCh activity.

7. The actions of SCh and of acetylcholine emphasized the differences in response of primary and secondary afferent endings to dynamic stretching. The use of these drugs enabled us to classify fibres of intermediate conduction velocity.

8. Suxamethonium is known to activate slow muscle fibre systems with distributed nerve endings. The similarity between dynamic fusimotor activity and the effect of SCh suggests that the dyanimic fusimotor fibres act on slow intrafusal muscle fibres through multiple distributed endings.
A comparison of the responses of frog skin receptors to mechanical and electrical stimulation
Authors: Catton W. T.
Published: December 2014

1. The latencies of spike responses evoked alternatively by brief mechanical (M) and electrical (E) pulses applied to single mechanoreceptive terminals in frog skin were compared on the same receptor.

2. Latency was found to be a maximum at threshold and to decrease with increased stimulus strength for both modes of excitation, but at all strengths M latency exceeded E latency. Mean maximum and minimum values for M latency were 4·8 and 2·85 msec; for E latency the maximum was 2·8 and minimum 2·3 msec.

3. At high frequency and strength of E stimulation there was an abrupt and marked shortening of latency to a fixed minimum value which ranged from 0·5 to 1·2 msec (mean 0·8). This was taken to be the response of the parent myelinated axon excited directly. The gap (1·5 msec) between the minimum value for the receptor response (2·3 msec) and the axonal response (0·8 msec) was taken to represent conduction time in the terminal branches of the sensory axon.

4. The response latency for excitation of the sensory terminal was also dependent on the duration of the stimulus pulse, but whereas the latency range for the M stimulus could be greatly extended that for the E stimulus was only slightly affected by increase in pulse duration.

5. The responses evoked by direct currents were complex, and consisted of an early brief discharge at the start of a cathodal current followed after a delay of 5‐30 sec by a prolonged multi‐fibre discharge which out‐lasted the stimulus. It is proposed that the sensory terminal is rapidly accommodating to current flow and that the delayed discharge is due to release of chemical material.

6. It is suggested that delay in mechanical excitation may be due to non‐rigid coupling of the receptor terminal to the skin tissues.
A visco‐elastic theory of mechanoreceptor adaptation
Authors: Catton W. T. , Petoe N.
Published: December 2014

1. Physical analysis of two visco‐elastic models was performed, to afford a quantitative basis for examination of a theory of slip as applied to mechanoreceptor adaptation. In one model the coupling force between skin tissue and receptor was considered to be purely viscous; in another it was supposed to consist of parallel viscous and elastic forces, representing the properties of a gel.

2. Predictions from the models were compared with experimental results from frog and rat skin receptors. Good fits with slope—latency and slope—amplitude curves were obtained, with the adjustment of two constants.

3. The excitability changes during long subliminal stimuli showed dynamic and static phases, which developed at different rates as stimulus strength was increased. This behaviour could be explained qualitatively by the more complex model, but quantitative comparisons could not be achieved.

4. Treatment of the skin with tissue‐destroying enzymes caused changes in stimulus‐response relationships consistent with predictions from the models. The effect of the enzymes seemed to be largely on the elastic coupling forces.

5. The visco‐elastic model offers a satisfactory but not exclusive explanation of certain time‐ and amplitude‐dependent features of mechanoreceptor behaviour and also accounts for a specific delay in mechanical excitation.
The uptake and release of radioactive noradrenaline by the splenic nerves of cats
Authors: Gillespie J. S. , Kirpekar S. M.
Published: December 2014

1.
DL‐[3H]noradrenaline was infused close‐arterially into the spleens of chloralosed cats at rates of 0·625 or 1·25 μg/min for 10 or 20 min and the recovery of noradrenaline and its metabolites in the venous blood measured during the infusion and after nerve stimulation at various times after the infusion.

2. During the infusion 41% of the noradrenaline was recovered in the blood as such and 11% as metabolites. The remaining 48% was retained within the spleen.

3. The noradrenaline retained in the spleen was slowly released to appear as metabolites in the blood stream. In normal animals the rate of loss from the spleen was 0·22% per minute. In animals given phenoxybenzamine after the end of the infusion this rate was several times greater.

4. Splenic nerve stimulation in normal animals or in animals treated with phenoxybenzamine resulted in an increase in the radioactivity of the blood leaving the spleen. Paper chromatography showed this to be radioactive noradrenaline.

5. In normal animals the specific activity of the transmitter liberated by nerve stimulation was less than that of the stores of noradrenaline within the spleen. In animals treated with phenoxybenzamine these two values were similar.

6. It is suggested that the infused noradrenaline retained in the spleen is largely taken up into nerve fibres and is available for subsequent release by nervous activity.
The histological localization of noradrenaline in the cat spleen
Authors: Gillespie J. S. , Kirpekar S. M.
Published: December 2014

1. The histological localization of noradrenaline in the cat spleen has been studied with a fluorescence technique and, after infusing
DL‐[3H] noradrenaline, both by the fluorescence technique and by autoradiography.

2. In the normal cat spleen the specific fluorescence of catecholamines is confined to nerve fibres among the smooth muscle of the capsule, trabeculae, arteries and veins. These fluorescent fibres are not present after treating the animal with reserpine or after degeneration of the postganglionic splenic nerves.

3. The splenic artery outside the spleen has few visible terminal adrenergic fibres. This is associated with the presence of an external elastic lamina. No terminal fibres were found in the walls of the main splenic vein.

4. After infusing
DL‐[3H]noradrenaline 1·25 μg/min for 10 or 20 min fluorescence remained confined to the same sites as in normal cats, i.e. in fibres related to smooth muscle. The red and white pulp and the smooth muscle itself remained free of fluorescence. Autoradiography showed radioactivity in similar sites and with the same pattern as the fluorescent fibres. These results support the conclusion reached in the previous article that noradrenaline infused into the spleen is bound to adrenergic nerves.
Recovery of responsiveness of cells of lateral geniculate nucleus of rat
Authors: Burke W. , Sefton Ann Jervie
Published: December 2014

1. Recovery of responsiveness of single cells in lateral geniculate nucleus of rat has been determined in both P and I cells. There are three types of recovery curve among P cells; (a) early recovery, (b) early partial recovery followed by depression and then complete recovery, (c) prolonged depression followed by cyclic recovery. Type (c) is by far the commonest recovery curve. In contrast to the spike in a P cell, the synaptic potential recovers to its full amplitude in about 20 msec. All I cells exhibit similar rapid recovery curves after a prolonged depression.

2. Conditioning stimuli applied to visual cortex also produce a prolonged depression in most P cells but I cells can be re‐excited at short intervals from cortex. Decortication does not prevent the prolonged depression of the multineuronal response produced by optic nerve stimulation.

3. A neuronal model is proposed to explain these observations. It is supposed that I cells (interneurones) are innervated by axon collaterals of the P cells (principal cells, projecting to visual cortex) and that the I cells exert an inhibitory influence on the P cells.
Inhibitory mechanisms in lateral geniculate nucleus of rat
Authors: Burke W. , Sefton Ann Jervie
Published: December 2014

1. An examination was made of the mechanisms responsible for the inhibition of synaptic transmission through the lateral geniculate nucleus (LGN) of the rat following a single shock to the optic nerve.

2. In the rat anaesthetized with paraldehyde we found no evidence that optic nerve stimulation produced any presynaptic inhibition in LGN. In agreement with other workers it was found that repetitive stimulation of visual cortex produced effects attributable to presynaptic inhibition. However, this was of small magnitude in the conditions of our experiments.

3. Stimulation of the optic nerve elicited an action potential in a P cell (principal cell) which was followed by a wave of hyperpolarization lasting about 150 msec (inhibitory post‐synaptic potential, IPSP, wave).

4. The IPSP wave was chloride‐dependent and was associated with inhibition of the P cell discharge. Occasional rippling on the IPSP wave suggests that it was produced by the repetitive discharge of I cells (interneurones).

5. These observations support the model proposed previously wherein P cells are inhibited by I cells which in turn are excited by axon collaterals of P cells. There is evidence for diffuse interconnexions between P cells and I cells.

6. The observation that the extracellularly recorded wave of hyperpolarization (P‐wave) is usually negative suggests that most of the inhibitory synapses are not on the soma of the P cell.
The effect of propranalol on the calorigenic response in brown adipose tissue of new‐born rabbits to catecholamines, glucagon, corticotrophin and cold exposure
Authors: Heim T. , Hull D.
Published: December 2014

1. Experiments measuring the rate of oxygen consumption of unanaesthetized new‐born rabbits and the blood flow in brown adipose tissue of anaesthetized new‐born rabbits are described.

2. The increase in rate of oxygen consumption caused by
I.V. infusion of noradrenaline, adrenaline and isoprenaline (2 μg/kg.min for 10 min) was blocked by propranalol (
I.V. 1 mg/kg) but the increase caused by cold exposure was not. A larger dose of propranalol (5 mg) blocked the calorigenic response to cold exposure as well.

3. Infusion of glucagon (
I.V. 4 μg/kg.min for 10 min) caused a large increase in the rate of the rabbit's oxygen consumption and in blood flow through its brown adipose tissue. These responses, which reached a maximum within 10 min from the start of the infusion, were not blocked by propranalol (1 or 5 mg/kg).

4. Infusion of corticotrophin (
I.V. 1 i.u./kg.min for 10 min) also caused a large increase in the rate of oxygen consumption of new‐born rabbits. The response reached a maximum about 20 min from the start of the infusion and it was not blocked by propranalol (5 mg/kg).

5. These results support the conclusion that noradrenaline is released at sympathetic endings in brown adipose tissue and that the increase in blood flow caused by noradrenaline is secondary to its metabolic action on the tissue. They also suggest the possibility that glucagon and corticotrophin may act directly on brown adipose tissue and stimulate heat production during cold exposure.
A thermal component of excitation in the lateral eye of Limulus
Authors: Srebro R.
Published: December 2014

1. The temperature dependence of the relative spectral sensitivity of the excised lateral eye of Limulus was examined using its electrical response to light.

2. At wave‐lengths longer than 625 mμ lowering the temperature from 27 to 7° C reduced the relative spectral sensitivity, while no effect was measurable at shorter wave‐lengths.

3. The reduction in relative sensitivity increased linearly with decreasing wave number.

4. The observations support the hypothesis that a critical amount of energy (activation energy) must be supplied to the photopigment molecule in order that it excite the photoreceptor. Quanta with energy lower than the activation energy are effective only if the thermal energy of the molecule can supply the deficit.

5. The lower limit of the activation energy for the photoreceptor of the lateral eye of Limulus determined from the results of this study is 44 kcal mole−1.
The rise in clotting factor VIII induced in man by adrenaline: effect of α‐ and β‐blockers
Authors: Ingram G. I. C. , Jones R. Vaughan
Published: December 2014

1. Human subjects received intravenous infusions of adrenaline preceded by saline, phentolamine (an α‐blocker) or either pronethalol or propranalol (β‐blockers), in different experiments.

2. Clinical measurements of blood pressure and pulse rate confirmed that α‐ or β‐blockade had been achieved.

3. The rise in clotting factor VIII induced by adrenaline was blocked by pronethalol and propranalol but not by phentolamine. This indicated that the effect of adrenaline on factor VIII was mediated by β‐receptors.
Effects of saline loading on the perfused cat kidney
Authors: Lockett Mary F.
Published: December 2014

1. Isolated cat kidneys perfused at constant pressure with blood from normal animals respond either to infusion or to injection of 0·9% NaCl (5‐20 ml./150 ml. blood) by diuresis, natriuresis, a fall of the Na concentration in the urine, a fall followed by a rise in urinary Na/K and a rise in renal blood flow. The filtration fraction remains unchanged (Figs. 1, 2).

2. Kidneys perfused either with blood from intact donors at constant blood flow or with blood from hypophysectomized donors at constant pressure show no vascular response to dilution of the blood with 0·9% NaCl. Saline dilution still causes diuresis and natriuresis. The concentration of urinary Na rises, as does Na/K without an initial fall (Figs. 3, 4).

3. Kidneys perfused with blood from headless animals are unable to respond to saline loading (Fig. 6).

4. Extracts of posterior hypothalamus convert the modified response of the kidney perfused with blood from hypophysectomized animals on dilution of the blood with saline to the response given when blood from intact animals is used (Figs. 3‐5).

5. Renal responses to saline loading are shown to be due to two hormones, and are dependent on the presence of an unidentified intracranial hormone, related to hypophysial hormones.
Activity of the human eccrine sweat gland during exercise in a hot humid environment before and after acclimatization
Authors: Peter J. , Wyndham C. H.
Published: December 2014

1. Six unacclimatized African mine labourers were subjected to exercise for 4½ hr in a hot humid environment (90°‐93° F wet‐bulb/dry‐bulb (
W.B./D.B.); approximately 90% r.h.)

2. The patterns of glandular activity and the densities of active glands on the chest and back were assessed half‐hourly from plastic impressions.

3. Acclimatization increased and prolonged glandular activity. The increment in activity of the sweat glands on the back was greater than that on the chest.

4. There was no significant increase in the maximum number of active glands on either site after acclimatization.

5. Acclimatization greatly reduced the number of inactive glands, subsequent to the maximum count, on the back, but this was not observed on the chest.

6. The increased sweat rates with acclimatization were due mainly to increased glandular activity.

7. The decline in sweat rates and activity on prolonged exposure to hot humid environment was attributed to glandular fatigue. Other factors, such as increased body temperature, hydration of the skin and fatigue of the central nervous system, suggested by other investigators as possibly causing the decline in sweat rates, did not have support in this study.
Vasodilatation in the submaxillary gland of the rabbit
Authors: Morley J. , Schachter M. , Smaje L. H.
Published: December 2014

1. In the rabbit, in contrast to the cat and dog, the vasodilatation and the secretion in the submaxillary gland which accompany parasympathetic nerve stimulation are correspondingly sensitive to atropine block.

2. It is concluded that true vasodilator nerve fibres to the submaxillary gland exist in the chorda tympani nerve of the rabbit.

3. The vasodilatation which follows sympathetic vasoconstriction in the submaxillary gland of the rabbit is small and variable. The possibility that this after‐dilatation is due to an adrenergic neurotransmitter agent acting on β‐vascular receptors is discussed.
Concealed glomerular filtration
Authors: Brewin E. G. , Ekins R. P. , Nashat F. S. , Portal R. W.
Published: December 2014

1. An increase in apparent renal clearances is frequently observed on restoring urine flow after a period of anuria or on increasing it after oliguria. An analysis of such ‘peaks’ in clearance has been made in experiments on anaesthetized dogs, using two preparations of labelled vitamin B12 and urine collections of 1–2 min. [57Co]B12 was infused throughout the experiments, while [58Co]B12 was given as a single injection during periods of anuria or oliguria induced by noradrenaline infusion, haemorrhage or aortic obstruction.

2. The apparent high clearance in the first minute or two of restored or increased flow is an artifact explained by inclusion in the peak of material filtered earlier, but not excreted. By means of the integrated plasma concentration ratio of the two B12 isotopes during the period of low or absent flow, the excess B12 in the peak may be reapportioned between the period before the 58Co was injected and the period after it.

3. The findings indicate that filtration may temporarily continue during anuria, but this is concealed as a result of failure of onward flow of filtrate. In oliguria a similar concealment of filtration may result from the cessation of onward flow in some nephrons.
Motor responses of the urinary bladder and skeletal muscle in Botulinum intoxicated rats
Authors: Carpenter F. G.
Published: December 2014

1. Type A or type D botulinum toxin administered to rats did not produce a generalized paralysis of skeletal muscles at the time of ventilatory arrest. However, if survival was extended by artificial ventilation complete blockade of neuromuscular transmission developed 6·5 hr after 100 MLD of type D and 5 hr after 1000 MLD of type A toxin. The onset of paralysis of a muscle was shortened by repetitive stimulation of the motor nerves.

2. There was no consistent blockade of parasympathetically innervated viscera in animals dying after type A toxin. Animals given type D toxin displayed mydriasis and urinary retention before death.

3. Motor responses to electrical stimulation, of bladder preparations in vitro were more vulnerable to type D than to type A toxin. When somatic paralysis was complete in animals treated with type A or type D toxin the excised bladders produced pressure elevations 45 and 25%, respectively, of control preparations.

4. During electrical stimulation of bladder preparations nearly paralysed by either toxin, the ACh release was significantly diminished from controls. In the rat bladder botulinum toxin specifically disrupted the liberation of mediator from post‐ganglionic nerve endings.
The action of tubocurarine and atropine on the normal and denervated rat diaphragm
Authors: Beránek R. , Vyskočil F.
Published: December 2014

1. The potency with which tubocurarine chloride (TC) and atropine sulphate (AS) influence the amplitude of the end‐plate potentials was measured in the rat diaphragm. This effect was compared with the action of these drugs on brief depolarizations evoked by iontophoretic application of ACh to end‐plate‐free spots of the chronically denervated fibre.

2. TC and AS act similarly on e.p.p.s, but the concentrations necessary to cause the same effect are 2000‐times higher for AS.

3. The dose—response curves for both inhibitors are unchanged by prostigmine.

4. Ten to twenty‐five days after denervation the ACh‐potentials of the sensitized end‐plate‐free parts of the membrane are less responsive to curare than the normal e.p.p.s are. AS is as effective in blocking ACh potentials of denervated muscles as it is in blocking normal e.p.p.s. The curare/atropine coefficient (dose ratio for equal effect) is 0·0005 for e.p.p.s and 0·003 for ACh potentials of the denervated membrane.

5. Both blocking drugs reduce the amplitude of ACh‐potentials evoked in the end‐plate region of normally innervated rat diaphragm fibres as effectively as they reduce the amplitude of e.p.p.s.

6. Neither TC nor AS have a presynaptic action in concentrations markedly reducing the e.p.p. amplitude.
The respiration of the anterior byssus refractor muscle of Mytilus edulis (ABRM) after a phasic contraction
Authors: Baguet F. , Gillis J. M.
Published: December 2014

1. The oxygen consumption of isolated anterior byssus retractor muscle of Mytilus edulis (ABRM) has been measured at rest and after phasic contractions induced by a.c. stimulation.

2. The respiration was measured with a Clark oxygen electrode in successive periods of 5 or 15 min, at 20° C.

3. The resting respiration is 71·8 ± 2·4 n‐moles O2/g wet weight.min (mean ±
S.E., n = 70). It is increased by a release and decreased by a passive stretch.

4. After phasic stimulation of up to 30 sec the respiration is increased and returns to a slightly higher level than the resting level in an exponential fashion with a time constant of about 10 min.

5. The duration of stimulation does not change the time course of the excess respiration but it affects its magnitude. The amount of extra oxygen consumed, in n‐moles O2/g, is made up of a constant amount, 449 ± 102, and an amount that depends on the duration of stimulation (t, sec), which is given by t × 13·2 ± 4·3. When due account is taken for the tension developed, these parameters become 83·1 ± 20·7 and t × 1·24 ± 0·66 n‐moles O2/g muscle and kg/cm2 of tension. This regression analysis is based on forty‐eight data, with a residual error based on 5 degrees of freedom.

6. Release of the tension after the last stimulus of a 30 sec tetanus reduces by half the extra oxygen consumed during the recovery whereas the same release applied 5 min later has a much smaller effect. This suggests that relaxation is an active process.

7. From these measurements of the recovery metabolism the energy cost of the contraction was estimated and compared with this cost in vertebrate striated muscle. The constant item has about the same magnitude, but the item related to the duration of stimulation is about 250 times smaller.
The central release of acetylcholine during consciousness and after brain lesions
Authors: Collier B. , Mitchell J. F.
Published: December 2014

1. Acetylcholine (ACh) has been collected from the visual cortex of anaesthetized rabbits during stimulation of the lateral geniculate body and after cutting central nervous pathways. ACh has also been collected from the visual cortex of conscious, free‐moving rabbits.

2. After a unilateral ‘vertical’ lesion separating the geniculate body from more centrally situated nuclei, ACh release evoked from the contralateral cortex by geniculate body stimulation was abolished but evoked release from the ipsilateral cortex was only reduced.

3. After a bilateral, ‘horizontal’ lesion separating the thalamic nuclei from the reticular formation, unilateral geniculate stimulation gave an increased ACh release from the ipsilateral but not from the contralateral visual cortex.

4. The ‘vertical’ and ‘horizontal’ lesions had no permanent effect on the spontaneous release of ACh from the visual cortex.

5. Unilateral destruction of the geniculate body reduced the spontaneous release of ACh from the ipsilateral cortex but did not affect the contralateral release.

6. The spontaneous and directly evoked ACh release from chronically undercut areas of cortex was found to be considerably lower than from intact areas of cortex.

7. A high output of ACh was obtained from the visual cortex of conscious, free‐moving rabbits. The rate of ACh release was closely related to the activity and state of arousal of the animals.

8. These results support an earlier suggestion that two major ascending cholinergic systems exist in the rabbit brain. One pathway is the non‐specific reticulo‐cortical tract responsible for cortical arousal and the other is the more specific thalamo‐cortical pathway associated with augmenting and repetitive after‐discharge responses. The functional significance of these two cholinergic pathways and their role in the conscious animal are discussed.