bluuebunny/crossref_metadata_2025 huggingface dataset:
Cholinergic receptors at sympathetic preganglionic nerve terminals
Authors: Koketsu K. , Nishi S.
Published: December 2014

1. In the paravertebral sympathetic chain of bullfrogs, some part of the preganglionic nerve located within the ganglion was depolarized transiently when acetylcholine (ACh) was directly applied to the ganglion, particularly in the presence of an anticholinesterase (anti‐ChE). The axonal part of the preganglionic nerve, on the other hand, showed no detectable depolarization following direct application of ACh (with anti‐ChEs) to the interganglionic nerve trunk.

2. The ACh depolarization was markedly depressed by nicotine, and less markedly by (+)‐tubocurarine, whereas it was not affected by atropine. Nicotine, similar to ACh, transiently depolarized only the intraganglionic portion of the presynaptic fibres.

3. The action potentials, recorded from the axonal as well as the terminal parts of the preganglionic nerve, showed spike potentials followed by a marked negative after‐potential. The negative after‐potential was followed by a positive after‐potential which was markedly enhanced by repetitive nerve stimulation.

4. A slow negative potential followed the positive after‐potential in the repetitive responses of the terminal parts of the preganglionic nerve. The slow negative potential was enhanced by anti‐ChEs, eliminated by ACh and nicotine, and unaffected by atropine.

5. The amplitude of the action potentials of the terminal parts of the preganglionic nerve, and particularly that of the negative after‐potential, was significantly depressed during the development of ACh depolarization as well as the slow negative potential, indicating that the two types of slow depolarization originated in the intraganglionic portion of the presynaptic fibres, presumably somewhere near or at the nerve terminals.

6. ACh depolarization similar to that observed with bullfrog sympathetic ganglia was observed with rat superior cervical ganglia. The present experiments provide evidence that a certain part of the preganglionic nerve terminals is depolarized by the action of the transmitter released from their endings.
The effects of antral acidification on the gastric secretion stimulated by endogenous and exogenous gastrin
Authors: Magee D. F. , Nakajima S.
Published: December 2014

1. In conscious dogs with Heidenhain fundic pouches and denervated antral pouches control dose—response curves to gastrin pentapeptide or methacholine were constructed, both when the antral pouch was empty and when it was stimulated with ACh (0·5 g/100 ml.) in citrate buffer adjusted to pH 5·5 or 1·5.

2. When the antral pouches were irrigated with ACh (0·5 g/100 ml.) at pH 1·5 the acid outputs from the Heidenhain pouch in response to graded doses of gastrin pentapeptide or methacholine were significantly less at each dose level than those obtained with ACh at pH 5·5.

3. The acid outputs from the Heidenhain pouch in response to either pentapeptide or methacholine with or without antral irrigation with ACh at pH 1·5 were approximately equal. Therefore the difference between the dose—response curves obtained by stimulation with ACh at pH 5·5 and those obtained by stimulation with ACh at pH 1·5 represents gastrin release rather than release of an inhibitory hormone.

4. The pepsin outputs from the Heidenhain pouch during antral irrigation with ACh at pH 1·5 were significantly less than those obtained with ACh at pH 5·5 at each dose of methacholine.

5. The maximal pepsin output was significantly greater in response to methacholine than to gastrin pentapeptide.

6. Gastrin pentapeptide was not a significant stimulant of pepsin secretion from the Heidenhain pouch.

7. The intestinal phase of parietal secretion was not inhibited by bathing the separated antrum with acid.
The effect of an exteroceptive stimulus on milk ejection in lactating rats
Authors: Deis R. P.
Published: December 2014

1. The exteroceptive stimulus emanating from a lactating rat and the litter while suckling was used to induce milk ejection in another lactating mother 15 min before the replacement of her own litter. The effect of the external stimulus on milk ejection during one 30 min period and four 15 min periods of nursing was studied.

2. After being isolated for 9 hr the litter from the mother subjected to the exteroceptive nursing stimulus (induced rat) obtained a significantly greater amount of milk during 30 min of nursing than that obtained by the litter from the control mother.

3. When deaf mother rats were used the gain of milk by the litter showed no difference between the control and the induced mother. This result indicated that the effective external stimulus is an auditory one and is probably produced by the mother rat and the young while suckling.

4. The administration of oxytocin (Syntocinon, Sandoz) 20 m‐u./100 g body wt., 15 min before the replacement of the litter produced a milk ejection similar to that obtained under the influence of the auditory stimulus. This would indicate that the exteroceptive stimulus probably evokes the release of oxytocin from the neurohypophysis.

5. When nursing was performed in four periods of 15 min each the litter of the control mother obtained milk only in the second period of nursing while the litter of the induced mother obtained milk in all four periods of nursing and the amount of milk obtained in the whole hour was greater than that from the control rat.

6. The administration of oxytocin just before the replacement of the litter every 15 min produced milk ejection only in the first two periods of suckling in the control rats but the induced rats were capable of ejecting milk during all four periods.

7. The most satisfactory conclusion for the results obtained is that the
C.N.S. regulates both the release of oxytocin in response to suckling and the response of the mammary gland to oxytocin, in the lactating rat.
A direct synaptic connexion between the left and right giant cells in Aplysia
Authors: Hughes G. M. , Tauc L.
Published: December 2014

1. In Aplysia fasciata, intrasomatic stimulation of the giant cell (RGC) of the right upper quadrant of the abdominal ganglia is followed after a constant delay by the appearance of a synaptic potential recorded in the giant cell (LGC) of the left pleural ganglion.

2. The synaptic potential recorded in the LGC soma has a biphasic form (hence biphasic post‐synaptic potential or BPSP) consisting of a fast depolarizing phase of about 200‐800 μV amplitude and 0·15‐0·25 sec duration, followed by a slow hyperpolarizing phase of about 200‐800 μV amplitude and 1‐3 sec duration.

3. During repetitive stimulation summation results in an over‐all hyperpolarization at low frequencies (less than 5/sec) and an over‐all depolarization for higher frequencies. Very high frequencies (25/sec) of stimulation of the RGC may elicit a spike in the LGC.

4. Stimulation with two shocks showed increasing effects with shorter intervals on both the depolarizing and hyperpolarizing phase. These effects were progressive and there was no falling out of one of the two phases as might be expected if the BPSP was a composite of an inhibitory post‐synaptic potential (IPSP) and an excitatory post‐synaptic potential (EPSP).

5. The effects of artificially imposed polarization of the LGC through a second micro‐electrode suggest that the BPSP results from a chemical transmission mechanism for both its depolarizing and hyperpolarizing phases but electrical transmission cannot be excluded.

6. Curare has no effect on the BPSP and thus excludes a cholinergic transmission mechanism. Chloride ions injected into the LGC soma do not appear to modify the BPSP and hence it is concluded that the hyperpolarizing phase is different from IPSPs of the same cell.

7. No synaptic potential is recorded in the RGC following stimulation of the LGC, except in a single preparation in which the RGC soma was situated in the right pleural ganglion. In this case the synaptic potential recorded in both giant cells following stimulation of the other, was biphasic in form.

8. It is concluded that the BPSP is a unitary monosynaptic potential which is a characteristic feature of the organization of these two giant cells.
The relation of oxygen intake and velocity of walking and running, in competition walkers
Authors: Menier D. R. , Pugh L. G. C. E.
Published: December 2014

1. The oxygen intake of four Olympic walkers was measured while walking and running at varying velocities on a treadmill at an altitude of 1800 m.

2. The relation between O2 intake and running at speeds between 8 km/hr and 21 km/hr was linear. The relation for walking at speeds up to 8 km/hr followed an upward concave curve. These findings were similar to results obtained at sea level by other investigators.

3. For walking at speeds between 8 km/hr and 14·5 km/hr the relation of O2 intake and velocity was a straight line having a slope twice that of running.

4. Maximum O2 intake in walking averaged 60·0 ml./kg/min (range 55·8‐64·1 ml./kg/min) compared with 57·4 ml./kg/min (range 55·2‐60·2 ml./kg/min) in running. An international class long distance runner serving as a control reached a maximum O2 intake of 70 ml./kg/min.
Effect of a saline environment on sodium transport by the toad colon
Authors: Ferreira H. G. , Smith M. W.
Published: December 2014

1. Colons isolated from saline‐adapted or aldosterone‐injected toads maintained transmural potential differences with the serosal side positive to the mucosa. The short‐circuit currents of colons taken from aldosterone‐injected toads could be expressed quantitatively by the net flux of sodium measured isotopically. This did not apply to saline‐adapted colons where the net sodium flux was from serosa to mucosa.

2. The short‐circuit currents of colons taken from aldosterone‐injected animals increased as the sodium concentration was raised from 10 to 50 m
M, then decreased as the sodium concentration was further increased to 115 m
M. Adaptation to saline changed this relationship, the short‐circuit current becoming directly dependent on the sodium concentration.

3. Faecal sodium was higher than serum sodium in saline‐adapted toads. There was little or no change in the level of serum sodium or potassium. The urine of saline‐adapted toads also contained high concentrations of sodium.

4. The total and ouabain‐sensitive ATPase activities of mucosal scrapings taken from saline‐adapted colons were about half those found in the aldosterone‐injected animal. Ten per cent of the total ATPase activity could be inhibited by ouabain.

5. Microsomal fractions of mucosal scrapings taken from saline‐adapted toads contained 4 times less Na+ + K+‐activated ATPase than did corresponding fractions from aldosterone‐injected animals. High concentrations of sodium inhibited the microsomal ATPase activity irrespective of the previous conditions of adaptation.

6. Regulation of sodium movements across the toad colon appears to be a complex process with the mucosal cells changing their properties so that they either absorb or secrete sodium ions depending on the physiological state of the animal.
The effect of serum on the uptake of thyroid hormones by the perfused rat heart
Authors: Hillier A. P.
Published: December 2014

1. The effect of serum on the uptake of radioactive
L‐thyroxine and
L‐3,5,3′‐tri‐iodothyronine has been studied in the perfused rat heart.

2. With thyroxine binding protein (rat serum) in the perfusion fluid the uptake of both hormones is much reduced.

3. This inhibitory effect of serum on hormone uptake is greater with thyroxine than with tri‐iodothyronine.

4. Serum in the perfusion fluid accelerates the release of accumulated thyroid hormone from the rat heart.

5. High concentrations of thyroxine increased the thyroxine space of hearts perfused by solutions containing serum.
Some aspects of adenosine triphosphate synthesis from adenine and adenosine in human red blood cells
Authors: Whittam R. , Wiley J. S.
Published: December 2014

1. The synthesis of ATP has been studied in human erythrocytes. Fresh cells showed no net synthesis of ATP when incubated with adenine or adenosine, although labelled adenine was incorporated into ATP in small amounts.

2. Cold‐stored cells (3‐6 weeks old) became progressively depleted of adenine nucleotides but incubation with adenosine or adenine plus inosine restored the ATP concentration to normal within 4 hr. Incorporation of labelled adenine or adenosine into the ATP of incubated stored cells corresponded to net ATP synthesis by these cells.

3. Synthesis of ATP from adenosine plus adenine together was 75% derived from adenine and only 25% from adenosine, indicating that nucleotide synthesis from adenine inhibits the simultaneous synthesis of nucleotide from adenosine.
Identification of cone mechanisms in monkey ganglion cells
Authors: Gouras Peter
Published: December 2014

1. Blue, green, and red sensitive cone mechanisms have been studied in two types of on‐centre ganglion cells in the Rhesus monkey's retina.

2. One type of cell receives signals from both green and red sensitive cone mechanisms, both of which excite in the centre and inhibit in the periphery of the cell's receptive field. These cells discharge transiently to maintained stimuli of any wave‐length and are called phasic.

3. The second type of cell receives excitatory signals from only one cone mechanism, either blue, green or red sensitive, in the centre, and inhibition from another cone mechanism in the periphery of its receptive field. These cells discharge continuously to maintained stimuli of appropriate wave‐length and are called tonic.

4. Tonic cells outnumber phasic cells although both are found adjacent to one another throughout the retina. Phasic cells are relatively more common toward the periphery and tonic cells relatively more common toward the fovea.
Reconstruction of the repolarization process in cardiac Purkinje fibres based on voltage clamp measurements of membrane current
Authors: Noble D. , Tsien R. W.
Published: December 2014

1. The results of the voltage clamp experiments described in a preceding paper (Noble & Tsien, 1969) have been used to reconstruct the repolarization process in Purkinje fibres.

2. The results show that, at the beginning of the plateau, the instantaneous current—voltage relation has a region of net inward current which, in the absence of additional outward current, would prevent repolarization.

3. The activation of the outward current, ix1, overcomes this region of inward current within about 300 msec. This first phase of the plateau is limited mainly by the speed of activation of ix1 and, during this time, there exists a threshold for all‐or‐nothing repolarization. The calculated time course of this threshold corresponds well with that recorded experimentally in uniformly polarized preparations.

4. Once the net inward current has been abolished, the rate of repolarization is mainly limited by the membrane capacity, although ix1 continues to activate until about 500 msec. The outward current, ix1, begins to deactivate during the rapid terminal phase of repolarization, but it is not fully deactivated at the end of the action potential. A second action potential initiated at this time would therefore be shorter than the first.

5. The effect of the initial outward current transient, recently identified as largely chloride current (Dudel Peper, Rüdel & Trautwein, 1967 a), has been calculated. The result is a notch at the beginning of the plateau similar to that often recorded experimentally. The action potential duration is not greatly influenced by this current component.

6. The role of outward currents other than ix1 in repolarization is discussed. It is concluded that the outward current component primarily responsible for terminating the action potential may vary and depends on the action potential duration. In Purkinje fibres with action potentials of normal duration, ix1 is the main time‐dependent outward current involved.
Action of cocaine and chronic sympathetic denervation on vagal escape
Authors: Campos H. A. , Urquilla P. R.
Published: December 2014

1. The effect of cocaine has been studied on vagal escape and on the tachycardia due to vagal stimulation in the atropinized dog. All the dogs were submitted to acute cervical section of the spinal cord and acute or chronic sympathetic denervation.

2. Cocaine, 5 mg/kg or 40 μg/kg/min,
I.V., induces a significant enhancement of the ventricular escape. The effects of a continuous infusion of cocaine are more reproducible than those of a single injection of the drug.

3. Cocaine, 40 μg/kg/min,
I.V., potentiates the tachycardia due to vagal stimulation in the atropinized dog.

4. Chronic thoracic sympathectomy markedly retards the recovery of the ventricular rate from the inhibitory action of the vagus. Under this condition, the infusion of cocaine does not significantly enhance the ventricular escape.

5. These findings suggest that an adrenergic mechanism located at the sympathetic nerves supplying the heart is substantially involved in the phenomenon of vagal escape.
The effect of sodium and calcium on the action potential of the smooth muscle of the guinea‐pig taenia coli
Authors: Brading Alison , Bülbring Edith , Tomita T.
Published: December 2014

1. Spontaneous spike activity and action potentials evoked by external field stimulation were recorded, intracellularly and with the double sucrose gap method, from the smooth muscle of guinea‐pig taenia coli.

2. Replacement of external NaCl with sucrose (leaving 10 m
M‐Na in the buffer) caused hyperpolarization and stopped spontaneous activity within 10 min. Spikes could, however, be evoked for 2‐3 hr. The amplitude, the overshoot and rate of rise of the spike were increased.

3. In 10 m
M‐[Na]o the intracellular Na concentration was reduced from 35 to 24 m
M, shifting the Na‐equilibrium potential from +34 to ‐22 mV.

4. Excess Ca (12·5 m
M) caused hyperpolarization and increased membrane conductance. The amplitude and the rate of rise of the spike were increased, the threshold was raised and the latency of the spike evoked by threshold stimulation became shorter.

5. The effect of reducing the external Ca concentration depended on the Na concentration present, being greater with higher external [Na]o. When the membrane was depolarized and spikes deteriorated in low Ca (0·2‐0·5 m
M) reduction of Na to 10 m
M caused repolarization and recovery of the action potential.

6. Mn (0·5‐1·0 m
M) blocked spontaneous spike discharge after 20 min. Higher concentrations (more than 2·0 m
M) were required to block the evoked action potential.

7. The results indicate that the smooth muscle spike in taenia is due to Ca‐entry and that Na influences spike activity indirectly by competing with Ca in controlling the membrane potential.
The re‐distribution of cytochrome oxidase, noradrenaline and adenosine triphosphate in adrenergic nerves constricted at two points
Authors: Banks P. , Mangnall D. , Mayor D.
Published: December 2014

1. The experiments correlate certain changes in the ultrastructure of cat hypogastric nerves constricted at two points with the distribution of a mitochondrial enzyme (cytochrome oxidase), noradrenaline (stored in some of the vesicles with an electron dense core, i.e. granular vesicles) and adenosine triphosphate (ATP) (present in noradrenaline storage granules, mitochondria and the soluble fraction of the axon).

2. Noradrenaline (NA) and granular vesicles accumulated proximal but not distal to both constrictions. The total amount of NA and the concentration of granular vesicles above the first constriction was greater than that present in a similar piece of normal nerve, indicating that the cell body was continuing to produce the transmitter despite injury to its axon. The granular vesicles proximal to the first constriction were found in swollen or distorted axons and in new axonal outgrowths. It was concluded that the movement of NA in these constricted nerves was only centrifugal in direction.

3. Mitochondria and cytochrome oxidase accumulated on both sides of the two constrictions, indicating a bi‐directional movement of mitochondria in the damaged axons. The possibility that some of the increase in the cytochrome oxidase could be related to an increase in the number of mitochondria in cells other than neurones is considered.

4. The adenosine triphosphate content increased on both sides of the two constrictions. This increase developed more slowly and was less marked than that of the other two substances.

5. It was concluded that (a) there was a close correlation between the behaviour of noradrenaline and granular vesicles and between cytochrome oxidase and mitochondria, (b) the dense cored vesicles and the mitochondria moved independently of one another and at different rates after constriction of non‐myelinated axons, (c) while some of the changes may be attributed to an obstruction to the free movement of axoplasm others may be due to an active reaction to axonal injury, and (d) localized intraaxonal synthesis of noradrenaline and cytochrome oxidase did not occur between the two constrictions.
Sodium ions and the secretion of catecholamines
Authors: Banks P. , Biggins Rosemary , Bishop R. , Christian B. , Currie N.
Published: December 2014

1. Perfusion of bovine adrenal glands with a potassium‐free Tyrode solution results in an increased spontaneous release of catecholamines and an increased response to stimulation with carbamylcholine.

2. Perfusion with a Tyrode solution containing 70 m
M‐KCl causes a marked secretion of catecholamines and a subsequent inhibition of secretion in response to stimulation with carbamylcholine.

3. Perfusion with sodium‐free media abolishes or severely reduces the secretory response of the gland to carbamylcholine and to 70 m
M‐KCl although the basal secretion shows an initial rise.

4. Perfusion with sodium‐deficient media permits some retention of the secretory response.

5. A possible role for intracellular sodium ions in the secretion of catecholamines is discussed.
Adrenal secretion rates and adrenal tissue concentrations of pregnenolone, progesterone, 11βOH‐androstenedione and some other steroids in young pigs and dogs
Authors: Holzbauer Margarethe , Newport Helen M.
Published: December 2014

1. The rates were measured at which a number of different steroids were secreted by the adrenal gland of the eviscerated and nephrectomized young pig and dog.

2. In addition to cortisol and corticosterone the following steroids were consistently found to be present in the adrenal venous blood: pregnenolone, progesterone, 11βOH‐progesterone, androstenedione, 11βOH‐androstenedione and adrenosterone.

3. The sum of the latter steroids could amount to as much as 30% of the total steroid secretion.

4. A severe deficit in the blood volume increased the secretion of pregnenolone and the 17‐oxo steroids in the pig.

5. α‐ethyltryptamine failed to inhibit ACTH release if the animals were eviscerated and nephrectomized, or if they were anaesthetized with chloralose instead of pentobarbitone sodium.

6. The same steroids as in the adrenal venous blood were found in extracts from the adrenal glands of a number of species.

7. The amount of individual steroids present in the adrenal gland of the stressed pig and dog was compared with the rate at which each had been secreted immediately before the excision of the gland.

8. There was a positive correlation between the adrenal concentrations and the secretion rates of cortisol, the major glucocorticoid secreted by the pig and the dog.

9. In contrast, the rate at which pregnenolone was secreted did not show a consistent relationship to its concentration in the gland.

10. A storage mechanism for pregnenolone in the adrenal cortex is proposed.
Hypoxaemia and aortic chemoreceptor function in foetal lambs
Authors: Dawes G. S. , Duncan Sheila L. B. , Lewis B. V. , Merlet Claudie L. , Owen-Thomas J. B. , Reeves J. T.
Published: December 2014

1. In foetal lambs the effect of raising and lowering arterial PO2 (by varying the O2 content of the maternal inspired gas mixture) was studied in order to determine whether the systemic arterial chemoreceptors regulated the circulation.

2. From 0·7 of term relative hypoxaemia (e.g. reducing carotid PO2 from 40 to 20 mm Hg) caused a rise of arterial pressure and femoral vaso‐constriction. These changes were unaffected or even increased by bilateral section of the nerves from the carotid sinus and body. They were abolished by section of the vagi or aortic nerves.

3. It is concluded that in foetal lambs during the last third of gestation the circulation is under reflex control by the aortic chemoreceptors.
Spontaneous activity of single neurones in the hypothalamus of rabbits during sleep and waking
Authors: Findlay Alan L. R. , Hayward James N.
Published: December 2014

1. A method is described for recording from single cells in the hypothalamus of unanaesthetized freely moving rabbits. Behaviour, bodily movement, skin and brain temperatures and e.e.g. were monitored.

2. Patterns of unit firing during slow sleep, paradoxical sleep and waking were studied in several regions of the hypothalamus, thalamus and in the septum.

3. Of the 144 cells analysed from waking to slow sleep, fifty‐six (39%) decreased mean firing rates, thirty (21%) increased spike discharges and fifty‐eight (40%) showed no marked change. Dorsal hypothalamic and massa intermedia thalamic cells fired in brief high frequency clusters during slow sleep with a characteristic ‘bimodal’ interspike interval histogram. Waking and paradoxical sleep abolished these cluster discharges with a concomitant change to an ‘asymmetric’ histogram.

4. Of the thirty‐two cells observed during the three states of waking, slow sleep and paradoxical sleep, a majority (twenty‐five or 78%) showed their highest rates of spontaneous discharge during paradoxical sleep. Discharge rates of cells sometimes changed in the course of paradoxical sleep according to the presence or absence of phasic events such as myoclonic motor activity. Two hypothalmic cells were almost totally arrested during paradoxical sleep.

5. Analysis of unit firing rates during spontaneous rises in brain temperature during waking and paradoxical sleep revealed that a majority of the neurones (22/24) changed their discharge rates in relation to behaviour rather than to brain temperature. Two cells did appear to respond specifically to the central thermal stimulus.

6. Hypothalamic cells do not behave as a homogeneous population in relation to changes in the state of arousal of the rabbit. Spontaneous changes in cell discharge related to sleep‐waking behaviour must be considered in any interpretation of hypothalamic unit activity as related to neuroendocrine or autonomic mechanisms.
The role of a renal thirst factor in drinking induced by extracellular stimuli
Authors: Fitzsimons J. T.
Published: December 2014

1. Rats in normal fluid balance drank water 1–2 hr after complete ligation of the inferior vena cava either above or below the renal veins. At the same time there was a fall in urine flow and excretion of electrolyte, especially after caval ligation above the renal veins, so that the animals ended the initial 6 hr period in positive fluid balance.

2. Caval ligation was relatively ineffective as a stimulus to drinking after bilateral nephrectomy, but was effective in rats made anuric by ureteric ligation.

3. Rats subjected to caval ligation and offered a choice between water and 1·8% saline (w/v) drank water, despite the increasing hypotonicity of the body fluids thereby resulting.

4. During the secondary polydipsia, which generally occurred on about the third day after caval ligation as renal function was recovering, there was an increased preference for 1·8% saline.

5. Constriction of the aorta above the renal arteries, or constriction of both renal arteries, also caused drinking, oliguria and the development of positive fluid balance.

6. Constriction of the aorta below the renal arteries, or after nephrectomy, was ineffective as a stimulus to drinking.

7. Saline extracts of renal cortex caused rats in normal water balance to drink. Activity was destroyed by boiling the extract for 10 min. Renal medullary and hepatic extracts were without effect on drinking.

8. It proved impossible to separate dipsogenic and pressor activities of renal extracts during the different stages of fractionation which lead to the production of renin; disappearance of one activity was invariably accompanied by disappearance of the other.

9. Dipsogenic and pressor actions were greater in nephrectomized rats than in normal rats.

10. Both extractable dipsogenic factor and extractable pressor activity were reduced by treating the rat with DOCA and saline for several weeks beforehand.

11. The renal dipsogen therefore has similar properties to renin. It may prove to be identical with renin, particularly in view of the fact that angiotensin also stimulates drinking.

12. Adrenalectomy did not affect drinking induced by renin or by caval ligation.

13. It is concluded that the renin angiotensin system may play a role in the genesis of the thirst which follows certain extracellular stimuli.
The time course of red cell lysis in hypotonic electrolyte solutions
Authors: Bowdler A. J. , Chan T. K.
Published: December 2014

1. Osmotic haemolysis of a standard suspension of human red cells was followed using a recording spectrophotometer at wave‐lengths between 600 and 650 mμ.

2. Optical density changes in the cell suspensions were related to turbulence of the suspension, cell swelling and loss of haemoglobin‐containing cells.

3. The time course of the loss of cells from suspension in hypotonic electrolyte solutions showed two phases: an early rapid phase was followed by a smaller phase of longer half‐time.

4. The second phase was most prominent in the middle ranges of partial haemolysis and less when total haemolysis was at the extremes of the detectable range.

5. The second phase was eliminated by the inclusion of 20 m
M sucrose in the suspension, and was slowed by the presence of 0·005% tannic acid without alteration of magnitude.

6. The magnitude of the second phase was dependent on the dominant external cation, becoming progressively greater through the series: Mg2+ < Na+ < Li+ < K+ < Rb+.

7. The slow phase is interpreted as arising from passive cation permeability in cells swollen to a volume close to that critical for haemolysis, with water influx secondary to the unopposed colloid osmotic pressure of intracellular protein.
Analysis of synaptic efficacy in spinal motoneurones from ‘quantum’ aspects
Authors: Kuno M. , Miyahara J. T.
Published: December 2014

1. Synaptic responses of triceps surae motoneurones of the cat following stimulation of single afferent fibres were examined by intracellular recording techniques.

2. The mean quantum content (m) of monosynaptic excitatory postsynaptic potentials (EPSPs) was independent of the type of motoneurone recorded and of the afferent fibre stimulated. There was no significant difference in m value between homonymous and heteronymous synapses.

3. A positive correlation was found between the amplitude of unit EPSPs and the input resistance of motoneurones. The difference in the amplitude of unit EPSPs appears to be responsible for the higher synaptic efficacy in slow‐conducting motoneurones than in fast‐conducting motoneurones.

4. There was no significant difference in the time course of monosynaptic EPSPs evoked by impulses from homonymous and heteronymous afferent fibres.

5. The ratio of monosynaptic connexions from a given afferent fibre was significantly greater on to homonymous than to heteronymous motoneurones. It is concluded that the difference in efficacy between homonymous and heteronymous synaptic transmission is due to the difference in the number of afferent fibres converging upon these motoneurones.
Cat colour vision: one cone process or several?
Authors: Daw N. W. , Pearlman A. L.
Published: December 2014

1. Peripheral mechanisms that might contribute to colour vision in the cat have been investigated by recording from single units in the lateral geniculate and optic tract. Evidence is presented that the input to these cells comes from a single class of cones with a single spectral sensitivity.

2. In cats with pupils dilated a background level of 10–30 cd/m2 was sufficient to saturate the rod system for all units. When the rods were saturated, the spectral sensitivity of all units peaked at 556 nm; this was true both for centre and periphery of the receptive field. The spectral sensitivity curve was slightly narrower than the Dartnall nomogram. It could not be shifted by chromatic adaptation with red, green, blue or yellow backgrounds.

3. In the mesopic range (0·1–10 cd/m2), the threshold could be predicted in terms of two mechanisms, a cone mechanism with spectral sensitivity peaking at 556 nm, and a rod mechanism with spectral sensitivity at 500 nm. The mechanisms were separated and their increment threshold curves measured by testing with one colour against a background of another colour. All units had input from both rods and cones. The changeover from rods to cones occurred at the same level of adaptation in both centre and periphery of the receptive field. Threshold for the cones was between 0·04 and 0·25 cd/m2 with the pupil dilated, for a spot covering the centre of the receptive field.

4. None of the results was found to vary between lateral geniculate and optic tract, with layer in the lateral geniculate, or with distance from area centralis in the visual field.

5. The lack of evidence for more than one cone type suggests that colour discrimination in the cat may be a phenomenon of mesopic vision, based on differences in spectral sensitivity of the rods and a single class of cones.
Rat brain amines, blood histamine and glucose levels in relationship to circadian changes in sleep induced by pentobarbitone sodium
Authors: Friedman Alexander H. , Walker Charles A.
Published: December 2014

1. The circadian patterns for onset and duration of sleep after the administration of a constant dose of pentobarbitone sodium have been measured in rats adapted to and maintained under a fixed illumination cycle. The relationship of these patterns to others for rectal temperature and motor activity as well as for noradrenaline (NA), 5‐hydroxytryptamine (5‐HT) and histamine in mid‐brain and caudate nucleus, and histamine and glucose in blood serum, has been examined.

2. The onset of sleep is longest and duration shortest during the phase of the illumination cycle when motor activity and rectal temperature are maximal. An inverse relationship for these parameters is found during the light phase of the illumination cycle.

3. In untreated rats, mid‐brain NA and histamine and caudate nucleus histamine levels are maximal and 5‐HT minimal during the dark phase of the illumination cycle. An inverse relationship for these parameters is found during the light phase of the illumination cycle.

4. Pentobarbitone sodium treatment significantly elevates mid‐brain NA and histamine and caudate nucleus histamine levels during the dark phase of the illumination cycle. Although 5‐HT levels are reduced over the entire circadian cycle this change is significant only during the light phase of the illumination cycle.

5. Pentobarbitone sodium treatment reverses the circadian pattern for body temperature, producing a mirror image of the control pattern.

6. The circadian pattern for blood serum histamine levels differs from the
C.N.S. pattern for histamine. Peak levels occur at the end of the light phase of the illumination cycle. After pentobarbitone sodium these levels are reduced, although the circadian pattern is similar to the control.

7. Circadian blood glucose patterns have bimodal peaks; a primary peak at the end of the dark phase, a secondary peak at the end of the light phase of the illumination cycle. Pentobarbitone sodium did not significantly alter the pattern. The relationship between this pattern and
C.N.S. and peripheral histamine and catechol amines is discussed.
Chloride fluxes in crab muscle fibres
Authors: Richards C. D.
Published: December 2014

1. Isotopic techniques were used to study the efflux of Cl− from single cannulated muscle fibres of the crab Maia squinado.

2. The efflux of 36Cl− was found to be exponential with steady rate constants ranging from 0·01 to 0·07 min−1. The steady efflux was ca. 1000–2000 p
M cm−2 sec−1. The efflux was slightly depressed by K+‐free saline and was unaffected by 40 m
M‐K+ saline and NO3− saline. The influx and efflux of Cl− were presumed independent.

3. The membrane conductance calculated from 36Cl− flux data was consistent with that determined by the method of electrotonic spread for other marine crustacean muscle fibres. Cl− accounted for most of the membrane conductance.
Reticulo‐ruminal mechanoreceptors in sheep
Authors: Leek B. F.
Published: December 2014

1. The nervous activity in single afferent gastric vagal units was recorded electrophysiologically from halothane‐anaesthetized sheep with spontaneous reticulo‐ruminal movements present.

2. Sixty‐six afferent units innervating gastric mechanoreceptors were isolated from fifteen sheep. The receptors were located mainly in the medial walls of the reticulum and the cranial sac of the dorsal rumen, and also in the reticular groove, the reticulo‐ruminal fold, the dorsal and ventral sacs of the rumen and the omasal canal.

3. The mean conduction velocity (
C.V.) for twenty‐seven units was 12·4 ± 1·0 m/sec (
S.E.). For units with a pathway in the dorsal vagal trunk, the mean
C.V. was 14·5 ± 1·0 m/sec (
S.E.) and for units with a pathway in the ventral vagal trunk the mean
C.V. was 6·6 ± 0·5 m/sec (
S.E.).

4. From the receptors a slowly adapting response was elicited by tangential lengthening. These were tension receptors in series with contractile elements, as they were excited by increased tensions developed both passively by inflation of the viscus and actively by muscular contractions.

5. Receptors in the reticulum and the rumen appeared to be situated deep in the muscle layers, whereas those in the reticular groove structures seemed to be more superficial and gave the in series tension receptor response as well as a response to light pressure.

6. A resting discharge in tension receptor units was usually absent at low levels of distension but appeared and increased as the level of distension was raised. Intermittency and fluctuations in the resting discharge were related to intrinsic local movement involving the receptive fields. Increasing distension enhanced the intrinsic movements.

7. Even after the removal of the abomasum, reticular and ruminal (primary cycle) movements were evoked by distending the reticulum. It is possible that this manoeuvre enhanced intrinsic movements, which, in turn, caused an increased excitatory afferent input to the ‘gastric centres’ from in series reticular tension receptors.

8. The enhanced afferent discharge from reticular tension receptors elicited by an isometrically recorded reticular contraction reflexly inhibited the subsequent (primary cycle) contraction of the rumen.

9. Very few receptors were located in the caudal regions of the rumen whereas the cranial sac is richly supplied with tension receptors. The idea that the cranial sac may serve as the reflexogenic zone for secondary cycle movements of the rumen is discussed.
The respiratory efficiency and flexibility of erythrocytes stored in acid‐citrate‐dextrose solution
Authors: Sirs John A.
Published: December 2014

1. Measurements have been made of the flexibility and respiratory efficiency of erythrocytes stored in acid‐citrate‐dextrose (ACD).

2. The rate of packing of stored blood, during centrifugation, indicates that the red blood cells are relatively inflexible.

3. Spectrophotometric observations, using the rapid‐mixing and stopped‐flow technique, indicate that the rate of egress of oxygen from HbO2 in these erythrocytes is significantly reduced. This is not due to a change of the chemical rate of dissociation of HbO2.

4. Neither factor is significantly reversed by resuspending the cells in Ringer‐Locke solution or adjusting to pH 7·4.

5. A small improvement is obtained by adding hypertonic NaCl or incubating the blood at 37° C for 1 hr.

6. Incubation with adenosine, 25 μ‐mole/ml. blood, at 37° C for at least 1 hr, restored both the respiratory function and flexibility to normal.
Resting potential and electrical properties of frog slow muscle fibres. Effect of different external solutions
Authors: Stefani E. , Steinbach A. B.
Published: December 2014

1. The electrical properties of frog slow muscle fibres were investigated with intracellular micropipettes to determine their characteristic length (λ), specific membrane resistance (Rm) and specific membrane capacitance.

2. The value of λ was about 1 cm in fibres of 1·2 cm length. The ‘short cable model’ was used to calculate Rm. Its mean value was 1·12 × 105 ohm cm2, about 10–20 times larger than the value for twitch fibres. The mean value for Cm was 3·24 × 10−6 F/cm2.

3. Resting potentials measured immediately after penetration with a single micropipette were about — 80 mV. Lower values can be attributed to the effects of damage or leakage produced by micropipette insertion.

4. Changes in external K concentration produced changes in the initially recorded resting potentials which follow the constant field theory using a ratio of Na: K permeabilities PNa/PK = 0·02. Changes in external Cl concentration produced little or no change in the resting potential or membrane resistance, indicating a low Cl permeability.

5. In agreement with previous work, slow fibres showed a time‐dependent decrease in resistance (‘delayed rectification’) for membrane potentials more positive than — 60 mV. ‘Anomalous rectification’ observed in twitch fibres was not seen in slow fibres. In high external K concentrations the resistance of slow fibres is almost unaffected by changes in membrane potential.

6. Increasing the concentration of external Ca (up to isotonic) has two distinct effects on slow fibres. It increases Rm up to ten times, and it improves the stability of trans‐membrane recordings, probably by reducing the leakage due to micropipette penetrations. Magnesium does not appear to have either of these effects.
Epipharyngeal receptors responding to mechanical stimulation
Authors: Nail B. S. , Sterling G. M. , Widdicombe J. G.
Published: December 2014

1. Action potentials were recorded from twenty‐one afferent nerve fibres from receptors in the epipharynx in anaesthetized, paralysed cats. Sixteen of the fibres had no spontaneous discharge.

2. Gentle mechanical stimulation of the epithelium of the epipharynx with a nylon fibre caused all twenty‐one receptors to discharge with rapidly adapting bursts of impulses at a mean peak frequency of 197 impulses/sec.

3. Stimulation with a stream of air through the epipharynx sufficient to distend the whole pharynx caused seven out of twelve receptors to discharge in rapidly adapting bursts. Stimulation with a jet of air directly on to the epithelium of the epipharynx caused seven out of nine receptors to discharge.

4. Chemical stimulation of the epipharynx with ammonia vapour caused an increased discharge in only three out of twenty receptors, and intravenous histamine had no effect on the four units tested.

5. It is concluded that the receptors mediate the ‘aspiration reflex’ elicited by mechanical stimulation of the epipharyngeal mucosa.
The mechanism of salt and water absorption in the intestine of the eel (Anguilla anguilla) adapted to waters of various salinities
Authors: Skadhauge Erik
Published: December 2014

1. The absorption of NaCl and water was studied by intraluminal in vivo perfusion of the intestine of the yellow European eel (Anguilla anguilla) adapted to fresh water (FW), to sea water (SW), and to double strength SW (DSW).

2. The net lumen to plasma NaCl transport from diluted SW perfusion fluids was independent of the NaCl concentration in the Na+ concentration range tested. The NaCl absorption (expressed as μ‐equiv/100 g.hr.) increased from FW (mean ±
S.E.): Na+ 166 ± 17, Cl− 205 ± 24 to SW: Na+ 363 ± 33, Cl− 423 ± 37, and again in DSW: Na+ 640 ± 110, Cl− 676 ± 149.

3. The osmolality of the perfusion fluid which resulted in zero net water transport was higher than plasma osmolality by 73 ± 3 m‐osmole in FW, 126 ± 5 m‐osmole in SW, and 244 ± 32 m‐osmole in DSW (mean ±
S.E.). A fairly constant ratio between net NaCl transport and this osmolality difference prevailed.

4. The general osmotic permeability to water in the serosa—mucosa direction (expressed as μl./100 g. hr. m‐osmole) measured from experiments with impermeant solute increased from FW: 3·7 ± 0·5 to SW: 7·2 ± 1·0 (mean ±
S.E.).

5. These results are compatible with the interpretation that the water flow occurring in the absence of a general transmural osmotic gradient, the ‘solute‐linked water flow’, is linearly related both to net NaCl transport and to the osmotic permeability to water. The findings support the view that the ‘solute‐linked water flow’ is, indeed, secondary to the salt movement and is due to osmotic force.

6. The amount of water absorbed from dilute SW perfusion fluids isosmotic with plasma was larger than in most other intestinal epithelia. FW: 650, SW: 1620 μl./100 g. hr. The NaCl concentration of the absorbate was hypertonic to plasma.

7. The passive permeability of the intestine to NaCl was very low, and the reflexion coefficient was close to unity. Therefore metabolic energy will be used to absorb NaCl, even when the NaCl concentration in the gut is higher than that of plasma due to ingestion of SW. There appears to be a limited interaction in the intestinal wall between passive salt and water flow.

8. In DSW the Na+ ingestion with the oral intake of the surrounding fluid matched the gut absorption capacity. Since DSW is close to the tolerance limit, it is concluded that the gut NaCl transport capacity may be one of the factors limiting the tolerance to water or higher salinity.
Visibility of aperiodic patterns compared with that of sinusoidal gratings
Authors: Campbell F. W. , Carpenter R. H. S. , Levinson J. Z.
Published: December 2014

1. Using experimental curves relating the threshold contrast of sinusoidal grating patterns to their spatial frequency, the expected threshold contrast curves for three aperiodic patterns, viz. a single half‐cycle sinusoid bar, a single full‐cycle sinusoid bar, and the boundary between an extended sinusoidal grating and a 50% grey surround, are calculated. In this calculation the assumption is made that the system is linear near the threshold.

2. Experiments are described in which the actual threshold contrast curves are determined for these aperiodic patterns by three observers. The patterns were generated on the face of an oscilloscope and could be varied in size and contrast.

3. These experimental curves agree well with the predictions in the high frequency region (i.e. above about 10 c/deg), but below this various complicating factors restrict the validity of the calculations.

4. Thus there is no reason to suppose that a linear theory cannot be used to predict visibility of aperiodic patterns near threshold.