bluuebunny/crossref_metadata_2025 huggingface dataset:
Site of origin of the abnormal discharge in the electrocorticogram produced by tubocurarine perfused through the anterior horn of a lateral ventricle
Authors: Feldberg W. , Fleischhauer K.
Published: December 2014

1. In cats anaesthetized with chloralose, perfusion of tubocurarine through the anterior horn of a lateral cerebral ventricle produces a rhythmic discharge of high voltage negative spikes recorded from an electrode inserted into this horn. The discharge spreads to the cerebral cortex where it gives rise to synchronous surface negative deflexions of low voltage. They have previously been described as ‘slow waves’.

2. The discharge results from an excitatory action of tubocurarine on the anterior limbic area, which is a cortical structure in the medial wall of the anterior horn lying rostral to the septum pellucidum.
Vestibular, cochlear and trigeminal projections to the cortex in the anterior suprasylvian sulcus of the cat
Authors: Landgren S. , Silfvenius H. , Wolsk D.
Published: December 2014

1. Cats anaesthetized with chloralose were used. Potentials evoked by electrical stimulation of the vestibular, cochlear, facial, trigeminal and chorda tympani nerves were recorded with micro‐electrodes in the cortex in the anterior syprasylvian sulcus.

2. Negative focal potentials with a latency of 3 msec were evoked by stimulation of the contralateral and ipsilateral vestibular nerves. These potentials were located in the lower and upper banks of the sulcus at a level just caudal to the projection of the Group I muscle afferents to the lower bank.

3. The cochlear projections were located mainly in the lower bank partially overlapping the vestibular and the Group I fields.

4. Trigeminal responses were recorded in both banks of the sulcus but were of largest amplitude and shortest latency rostrally in the upper bank. The potentials evoked by the chorda tympani had a similar distribution but were of low amplitude.

5. The hypothesis is suggested, that the cortex in the anterior suprasylvian sulcus plays a role in the orientation of the body and head towards auditory stimuli.
Potassium transport and nucleoside metabolism in human red cells
Authors: Whittam R. , Wiley J. S.
Published: December 2014

1. A study has been made of active cation transport in relation to the metabolism of nucleosides and deoxynucleosides in human red blood cells.

2. Lactate production from inosine depended on the cellular inorganic phosphate available for phosphorolysis and was raised to some 4 times the normal rate from glucose. Inosine inhibited glucose metabolism according to the amount of glucose‐6‐phosphate produced. Guanosine behaved similarly, but glucose‐6‐phosphate was not formed from adenosine, deoxyinosine and deoxyguanosine.

3. Glucose metabolism was related to the ATP content of the cells, which was raised by incubation with adenosine, or with inosine plus adenine.

4. Adenosine and deoxyadenosine raised the potassium influx above the values found with inosine and deoxyinosine under conditions when the lactate production was constant. Active potassium influx was correlated with the ATP concentration in the cells, but independent of the lactate production when the latter was raised above normal.
Acute effects of haemorrhage on the composition of arterial blood in immature and adult rabbits, kittens and cats
Authors: Mott Joan C.
Published: December 2014

1. The fall of haematocrit after stepwise bleeding in rabbits and young kittens was not accompanied by an equivalent fall of plasma nitrogen. The relative failure of plasma nitrogen to decrease after haemorrhage was not attributable to the entry of diffusible nitrogen into the circulation.

2. Plasma protein recovery by a combination of stepwise bleeding and viviperfusion was such as to yield values for the whole body/great vessel haematocrit ratio (Fcells) in the normal range in adult cats but significantly below the normal range in young kittens and rabbits. If viviperfusion was not preceded by stepwise bleeding Fcells in the normal range was obtained in young kittens and rabbits.

3. The results of electrophoretic examination of pre‐ and post‐haemorrhagic plasma were consistent with the entry of fresh protein into the circulation after haemorrhage occurring preferentially in the albumin fraction, but increase of albumin/globulin ratio was small in adult cats.

4. It was concluded that the fall of haematocrit after haemorrhage in young kittens and rabbits was mainly due to the entry of protein rich tissue fluid into the circulation. In adult cats, however, the haematocrit did not always fall and any such fall may have been partly due to a shift of plasma from the periphery to the great vessels.

5. The bearing of these observations on the validity of calculation of blood volume from red cell mass and haematocrit during stepwise haemorrhage was considered.
Sodium flux and electrical activity of arterial smooth muscle
Authors: Keatinge W. R.
Published: December 2014

1. The intracellular concentration and transmembrane flux of Na in smooth muscle cells of sheep carotid arteries were measured by identifying a fraction of tissue Na whose efflux was markedly sensitive to removal of external Ca. This allowed intracellular Na to be distinguished from extracellular bound Na exchanging with a similar time constant.

2. When the arteries were in solution containing Na 148 m
M and Ca 2·5 m
M the mean intracellular Na concentration was 7·3 m‐mole/kg cell water and the mean transmembrane flux of Na was 0·18 p‐mole cm−2 sec−1, both values being much lower than reported values for intestinal smooth muscle.

3. During electrical activity induced by Ca deprivation the influx of Na increased to 3·2 p‐mole cm−2 sec−1; a 50% reduction in Na concentration stopped electrical activity and reduced influx by more than 50%, and the excess Na influx per action potential was calculated to be at least 1·0‐1·5 p‐mole cm−2.

4. Arteries in physiological saline (Ca 2·5 m
M) contained 3·48 μmole Ca/g, much of which was bound extracellularly; in Ca‐free saline 1·39 μmole Ca/g left the tissue within 3 min, showing that extracellular dissolved Ca diffused freely out of the tissue.

5. The results provide further evidence that Na is the principal ion carrying the depolarizing current of action potentials in this smooth muscle.
Some effects of ouabain and potassium on transport and metabolism in rat small intestine
Authors: Newey H. , Sanford P. A. , Smyth D. H.
Published: December 2014

1. Ouabain (10−3
M) inhibited the transfer of glucose, proline, methionine and fluid but not of galactose and 3‐O‐methyl glucose by sacs of rat everted intestine.

2. Ouabain (10−3
M) inhibited both glucose and mannose metabolism. Hexose metabolism was also reduced by varying the [K] from 4·8 m‐equiv/l.

3. Ouabain (10−3
M) or absence of K reduced the stimulation of amino acid, hexose and fluid transfer by mannose. Although presence of ouabain or absence of K did not inhibit endogenous galactose transfer, these conditions prevented mannose from stimulating this transfer.

4. Ouabain (10−3
M) exerted greater effects on hexose and amino acid transfer when K was omitted from the saline and its inhibitory effects were partially overcome by increased serosal [K].

5. Ouabain (10−2
M) caused further inhibition of amino acid and glucose transfer and also reduced the transfer of galactose and 3‐O‐methyl glucose.

6. The implications of these results are discussed with respect to the relationships between cations and hexose and amino acid transfer.
Factors influencing the electrical potential across the mucosa of rat colon
Authors: Edmonds C. J. , Marriott Jane
Published: December 2014

1. An investigation has been carried out into various factors which influence the transmucosal potential difference (p.d.) of rat colon in vivo when the p.d. is either high (> 30 mV) or low (< 20 mV).

2. The p.d. was uninfluenced by short duration anaesthesia with ether or pentobarbitone. When anaesthesia was prolonged for several hours, p.d. rose steadily. The gradient of p.d. along the descending colon which developed and its elimination by adrenalectomy suggested that the rise was due to increased secretion of adrenal steroids.

3. P.d. was increased by Na depletion after a delay of about 18 hr and fell again following Na repletion with a similar time delay. A characteristic gradient of p.d. along the descending colon was seen.

4. Both haemorrhage and anoxia caused a rapid fall of p.d. P.d. was restored rapidly to its previous level when anoxia was corrected.

5. Vasopressin (
I.V.) in low dose was without effect; in high dose it caused a transient fall of p.d. associated with intense vasoconstriction of gut blood vessels.

6. The following factors studied were without effect on p.d.: presence of glucose within the lumen; considerable osmotic gradients across the mucosa; variation of luminal pH over the range 5·2‐9·8; intravenous administration of acetazolamide, chlorothiazide, frusemide, triamterene, ethacrynic acid or ouabain. Ouabain in the luminal solution also had no effect in all but two rats in which a small fall of p.d. was seen.

7. 2,4‐dinitrophenol, 10−2
M, in the lumen caused a small fall of p.d. only if the p.d. was high.

8. Experiments were done to determine the effect on p.d. of altering the ionic composition of the luminal solution. When the p.d. was low (< 20 mV) alteration of [Na], [K] or [Cl] produced small absolute changes of the p.d., all of comparable magnitude. The changes could be interpreted as due to diffusion potentials resulting from the ionic gradients across the mucosa. When the p.d. was high (> 30 mV), it showed a striking dependence on the luminal [Na] only, consistent with the presence of a large p.d. due to active Na transport.
A ouabain‐sensitive membrane conductance
Authors: Geduldig D.
Published: December 2014

1. Changes in membrane conductance and potential of sodium‐loaded frog muscle fibres were found when the external recovery solution was changed: from cold to warm, to warm plus ouabain, to cold plus ouabain. Comparisons of these measurements for different external solutions were made by leaving the electrodes implanted in the same fibre during all solution changes. (The recovery solutions contained 10 m
M‐K and 82 m
M‐Cl.)

2. The membrane potential became more negative on warming, less negative when ouabain was added, and still less negative when the ouabain‐containing recovery solution was cooled. The membrane conductance increased on warming, increased further on addition of ouabain, and decreased when the ouabain‐containing recovery solution was cooled.

3. The increase of conductance which occurred on warming decreased with increasing periods in cold recovery. The increase of conductance which occurred on addition of ouabain decreased if the ouabain was added to the recovery solutions of muscles which were more fully recovered.

4. The ouabain‐sensitivity of the membrane conductance may be dependent upon the sodium‐pump rate, or the extent of recovery of the sodium‐loaded muscle fibre in the potassium‐ and chloride‐containing recovery solutions.

5. It is suggested that if the potassium conductance of the membrane increases with decreasing sodium‐pump rates, then during the initial part of the recovery period a non‐electrogenic mechanism must be producing a substantial part of the early net potassium influx.
The ineffectiveness of excitation of the primary endings of the muscle spindle by vibration as a respiratory stimulant in the decerebrate cat
Authors: Hodgson H. J. F. , Matthews P. B. C.
Published: December 2014

1. Small‐amplitude high‐frequency longitudinal vibration (for example, 100 μ peak to peak amplitude at 250 c/s) was applied to the triceps surae muscle of the decerebrate cat without producing any appreciable change in its respiration.

2. Manual squeezing of the same muscle produced a large increase in ventilation.

3. As vibration is known to be a powerful stimulus for the primary endings of the muscle spindle it is concluded that these receptors are unlikely to have any significant role to play in the reflex regulation of breathing.
The effect of haemorrhage on haemoglobin concentration, blood volume and arterial pressure in kittens and cats
Authors: Mott Joan C.
Published: December 2014

1. The arterial haemoglobin concentration in kittens less than 24 hr old was inversely related to body weight. There was about twice as much haemoglobin/unit body weight at birth as in adult cats. Haemoglobin concentrations were minimal at 3‐6 weeks of age.

2. In animals lightly anaesthetized with sodium pentobarbitone, arterial pressure rose from 52 mm Hg at birth in kittens to 133 mm Hg in adult cats. Blood volume decreased from 73 ml./kg at birth to 60 ml./kg in adults.

3. When kittens less than a fortnight old were subjected to stepwise blood letting, arterial pressure fell proportionately with blood volume; in older kittens and in cats, arterial pressure was less well maintained at similar proportionate reductions of blood volume than in young kittens.

4. The responses to haemorrhage of kittens and cats were compared with those of rabbits similarly treated and with those of adult cats anaesthetized with urethane and chloralose reported in the literature.
The role of sodium and potassium in insulin secretion from rabbit pancreas
Authors: Hales C. N. , Milner R. D. G.
Published: December 2014

1. Insulin secretion from pieces of rabbit pancreas incubated in vitro was studied in media of different ionic composition and in response to different substances added to the media.

2. Experiments were performed which demonstrated that a sodium pump played a role in insulin secretion and that inhibition of the pump by ouabain, or by the omission of extracellular potassium, stimulated insulin secretion.

3. A rise in extracellular potassium concentration stimulated insulin secretion independently of changes in the osmolarity or sodium or chloride concentration of the incubation medium.

4. The role of extracellular sodium in insulin secretion was investigated. Extracellular sodium was a pre‐requisite for insulin secretion stimulated by glucose, glucagon,
L‐leucine, tolbutamide, potassium or ouabain.

5. The presence of 3·3 m
M glucose in the incubation medium was not essential for the stimulation of insulin secretion by
L‐leucine, tolbutamide or ouabain. Glucagon did not stimulate insulin secretion in the presence of 3·3 m
M glucose but did so in the presence of 16·5 m
M glucose.

6. The results obtained in these experiments suggested that a transmembrane sodium flux probably in the β cell was a fundamental event in the stimulation of insulin secretion by diverse stimuli.
Resting and action potentials recorded by the sucrose‐gap method in the superior cervical ganglion of the rabbit
Authors: Kosterlitz H. W. , Lees G. M. , Wallis D. I.
Published: December 2014

1. Evoked ganglionic action potentials and drug‐induced changes in resting potential were recorded by the sucrose‐gap method. The height of the action potential was 10‐20 mV.

2. Since the amplitude of the P wave is inversely proportional to the external potassium concentration between 0·5 and 12 m
M, the P wave is probably caused by a phase of increased permeability to K+.

3. In the absence of an anticholinesterase, the depolarizing actions of choline and acetylcholine on the ganglion are almost equal, whereas acetylcholine is 2‐3 times more potent than choline on the fibres of the internal carotid nerve. In the presence of eserine, acetylcholine induces a depolarization of the ganglion of up to 14 mV, while increase in [K+]o causes a depolarization of up to 55 mV.

4. Although the post‐ganglionic fibres in the distal pole of the ganglion are depolarized by drugs, for example, acetylcholine, they contribute little to drug‐induced potential changes and probably little to evoked action potentials.

5. The hyperpolarization which occurs after exposure of the ganglion to acetylcholine is not due to a phase of increased permeability to K+.
Bleached rhodopsin and retinal interaction
Authors: Westheimer Gerald
Published: December 2014

1. The human rod retina exhibits lateral inhibition which is demonstrated by the sensitization, i.e. improvement in incremental threshold sensitivity, of a steadily illuminated patch of retina when its surround is also illuminated.

2. Experiments were carried out to test whether the previously reported equivalence between steady illumination (real light) and signals from bleached rhodopsin (dark light) also carries over into lateral interaction.

3. Symmetrical experiments involving real light patches surrounded by dark‐light annuli, dark‐light patches surrounded by real‐light annuli, and dark‐light patches surrounded by dark‐light annuli showed that dark light is neither susceptible to sensitization by lateral interaction nor capable of exerting it.
The effect of calcium on contraction and conductance thresholds in frog skeletal muscle
Authors: Costantin L. L.
Published: December 2014

1. The effect of extracellular calcium and magnesium on the contraction threshold and on the thresholds for an increase in sodium and potassium conductance with depolarization was studied in voltage‐clamped frog muscle fibres.

2. A larger depolarization was required to reach each of the three thresholds when the concentration of divalent cation was increased.

3. The contraction and potassium conductance thresholds appeared to shift in parallel with alterations in calcium over the concentration range 0·2‐10·0 m
M and in magnesium over the concentration range 5·4‐90·0 m
M. The shift amounted to about 4 mV for a threefold change in concentration of divalent cation.

4. The sodium conductance threshold was much more sensitive to alterations in divalent cation concentration than was either the contraction or the potassium conductance threshold.
The mechanism of oxygen concentration in the swim‐bladder of the eel
Authors: Berg Trond , Steen Johan B.
Published: December 2014

1. The PO2 of venous blood from the active swim‐bladder of the eel was shown to decrease with distance from the exit of the rete. This systematic change did not occur in non‐secreting bladders, nor during conditions where exchange in the rete had been abolished.

2. The observed change in post‐rete venous PO2 has the same rate constant as the Root‐on shift.

3. These findings modify the accepted model for counter‐current multiplication of O2 in the swim‐bladder system by introducing rate constants for diffusion and action of acid in the rete.

4. The part played by the assumed impermeability to acid of the arteriovenous partition of the rete is in the modified model replaced by the slow Root‐on shift.

5. The modified model contradicts the Kuhn model in that extraction of O2 from blood is decreased at low flow and that at normal flow conditions part of the lactic acid produced can be re‐used.

6. Similar modifications are indicated in the model for concentration of inert gases.
The ionic content of mammalian non‐myelinated nerve fibres and its alteration as a result of electrical activity
Authors: Rang H. P. , Ritchie J. M.
Published: December 2014

1. A study has been made of the ionic content, and of the fibre water, of rabbit desheathed vagus nerves at rest and after activity in various modified Locke solutions.

2. In normal Locke solution the intracellular sodium amounted to 86·1 μmole/g dry, and the intracellular potassium 186·0 μmole/g dry. Since the fibre water amounted to 1·124 g/g dry the intracellular sodium and potassium concentrations were 76·6 and 165·5 m‐mole/kg fibre water, respectively.

3. In potassium‐free Locke solution the intracellular sodium and potassium concentrations were 111·0 and 121·7 m‐mole/kg, respectively. The intracellular chloride concentration was 40·5 m‐mole/kg.

4. In normal Locke solution, a brief period of stimulation followed by a 10 min recovery period produced no significant change in the intracellular contents of potassium, sodium, or water.

5. However, in chloride—Locke solution from which the potassium had been omitted, or to which ouabain (1 m
M) had been added, stimulation caused a loss of potassium per impulse of about 20 p‐mole/mg dry, i.e. about 4 p‐mole/mg wet. A similar loss was found in isethionate—Locke solution that was potassium‐free. There was no significant change in any of the other quantities measured (sodium, chloride, and fibre water).

6. The efflux of radioactively labelled potassium was measured in potassium‐free Locke solution at rest (kr) and during activity (ks). At 24° C, kr was 0·0084 min−1 and ks was 0·000178 impulse−1.

7. When the chloride of Locke solution was replaced by isethionate there was an increase in both kr (about 12%) and ks (about 21%).

8. Ouabain (1 m
M) increased ks (by about 70%). This increase seemed to be independent of whether the anion present was chloride or isethionate.

9. It is argued that these results indicate that the electrogenicity of the pump plays a relatively small role in maintaining the ionic balance in mammalina C fibres.
The effect of sodium concentration on the content and distribution of sodium in the frog skin
Authors: Cereijido M. , Reisin I. , Rotunno Catalina A.
Published: December 2014

1. The content and distribution of sodium in the epithelium of the frog skin (Leptodactylus ocellatus L.) have been studied.

2. The inulin space, the 22Na exchange, and the amounts of water and sodium were measured in samples of connective tissue. The results indicate that the necessary assumptions generally made to calculate the sodium and water contents of the epithelial cells as the difference between the total content in the tissue and the amounts contained in the inulin space are not valid in the frog skin.

3. The mean concentration of sodium in the epithelium has been obtained from direct measurements of sodium and water in samples of epithelium. To measure the water content of the epithelium a new technique has been developed. When the skin is bathed with Ringer solution containing 115 m
M‐Na on both sides, the mean concentration of sodium in the epithelium is 79 m
M. When the concentration of sodium in the Ringer is 1 m
M the mean concentration in the epithelium is 25 m
M. When the skin is bathed with Ringer with 1 m
M‐Na on the outside and 115 m
M‐Na on the inside—a situation which resembles the natural condition in the skin—the mean concentration of sodium in the epithelium is 52 m
M.

4. The compartmentalization of Na was studied by comparing the sodium content and the degree of exchange with 22Na in the bathing solutions. In these experiments the skins were exposed to Ringer solutions with different concentrations of sodium, and 22Na on one or both sides.

5. The results indicate that the epithelium has a compartment of sodium which is not exchangeable in 40‐80 min and whose size is not appreciably changed by a threefold change in the Na content in the epithelium and a hundredfold change in the concentration of the bathing solution.

6. Sodium exchangeable in 40‐80 min seems to be contained in two different compartments: (a) a large one that contains fixed sodium is mainly connected to the inside, and does not appear to participate directly in sodium transport across the frog skin; (b) a small one, that is bounded on the inside by a Na‐impermeable barrier, and that seems to comprise the sodium involved in active transport. When the skin is bathed with Ringer solutions with 115 m
M‐Na on the inside and 1 m
M‐Na on the outside, the transporting compartment contains some 13% of the total sodium in the epithelium.

7. The results are interpreted on the basis of a model recently proposed by Cereijido & Rotunno (1968). The major feature of this model is that the sodium transporting compartment is confined to the plasma membrane of the epithelial cells.
Studies on the longitudinal muscle of the anterior mesenteric artery of the domestic fowl
Authors: Bolton T. B.
Published: December 2014

1. A simple, isolated preparation is described in which the activity of the longitudinal muscle of the anterior mesenteric artery of the domestic fowl is recorded isotonically.

2. The longitudinal muscle of the anterior mesenteric artery exhibited tone and marked spontaneous activity. Maximal shortening of this muscle was equal to about 60% of its resting length.

3. Acetylcholine in low concentrations produced powerful contractions of the muscle, whereas low concentrations of catecholamines produced relaxation by an action on β‐receptors; much larger concentrations of adrenaline or noradrenaline contracted the muscle. A pharmacological analysis of the responses to electrical stimulation and to agonist drugs indicated that the muscle was supplied by excitatory, cholinergic nerves and by inhibitory, adrenergic nerves.
Electrical and mechanical activity of the longitudinal muscle of the anterior mesenteric artery of the domestic fowl
Authors: Bolton T. B.
Published: December 2014

1. The electrical activity and changes in tension of the longitudinal muscle of the anterior mesenteric artery (LMAMA) of the domestic fowl were recorded simultaneously using the sucrose‐gap method.

2. Spontaneous activity consisted of recurring contractions each accompanied by a burst of action potentials.

3. In quiescent preparations, brief electrical stimuli, acetylcholine, or barium chloride produced contractions with the appearance of action potentials. Larger concentrations of barium chloride or acetylcholine produced depolarization and action potentials ceased although contraction was maintained. Whenever depolarization without action potentials occurred, it was associated with a smooth contraction, whereas action potentials were always accompanied by small rapid contractions super‐imposed upon the main contraction.

4. When the tone was raised with barium chloride (and in the presence of hyoscine) continuous action potentials occurred; under these circumstances brief electrical stimuli or noradrenaline produced relaxation, cessation of action potentials, and hyperpolarization.
Facilitation of heart muscle contraction and its dependence on external calcium and sodium
Authors: Orkand R. K.
Published: December 2014

1. The magnitude and time course of the facilitation of contraction following previous stimulation have been studied in strips of frog ventricle when the external concentrations of Na and Ca were varied. The maximum tension and the maximum rate of rise of tension have been used as indices of activation of the contractile element. Under the experimental conditions these two parameters changed similarly.

2. At low stimulus frequencies (3‐12 beats/min), and moderate concentrations of external Ca (2‐5 m
M), the facilitation of contraction with repetitive stimulation can be predicted by assuming each contraction to produce an amount of facilitation which sums linearly with that remaining from previous responses. Thus, the staircase can be constructed from the decay of facilitation following a single contraction.

3. The decay of facilitation appears to consist of two components. The first has a half‐time of about 3 sec; the second about 50 sec. The decay of the second component of facilitation is slowed and its magnitude increased by raising the external Ca from 2 to 5 m
M.

4. Reducing the external Na concentration increases both the initial strength of contraction and the amount of facilitation.

5. When the ratio Ca/Na2 is kept constant while changing the Ca and Na concentrations, the first contraction in a series remains constant, but facilitation is less at low concentrations of Ca and Na. Facilitation, therefore, does not depend solely on the amount of initial activation of the contractile system.

6. The results are consistent with the hypothesis that facilitation depends on the amount of calcium retained in some cellular store.
The effects of bradykinin, angiotensin and acetylcholine on the bovine adrenal medulla
Authors: Comline R. S. , Silver Marian , Sinclair D. G.
Published: December 2014

1. The response of the adrenal medulla to the intra‐arterial injection of angiotensin, bradykinin and acetylcholine and to splanchnic nerve stimulation has been investigated in day‐old and 3‐ to 18‐month‐old calves and in adult cats.

2. Bradykinin and angiotensin had no appreciable effect on catecholamine release in the day‐old calf nor did these peptides potentiate the response of the gland to acetylcholine.

3. In older calves the response of the gland to bradykinin and angiotensin was marginally above the control output, whereas acetylcholine and splanchnic nerve stimulation caused a 10‐100 fold increase in the rate of secretion. The response to acetylcholine but not to the peptides was related to the dose administered.

4. The adrenal medulla of the cat was stimulated by angiotensin and bradykinin but the maximum amounts released by the peptides were much smaller than the discharge elicited either by splanchnic nerve stimulation or by acetylcholine. No dose—response relationship could be found for either adrenaline or noradrenaline released by angiotensin, or for noradrenaline released by bradykinin. The slight increase in adrenaline output which followed the injection of bradykinin was dependent on the dose but the slope of the curve (b = 0·161) was much less than that for acetylcholine (b = 0·636).
Neural control of salivary myoepithelial cells
Authors: Emmelin N. , Garrett J. R. , Ohlin P.
Published: December 2014

1. The pressures in the ducts of the submaxillary, parotid and sublingual glands were recorded in cats under chloralose anaesthesia. A single stimulus applied to the parasympathetic glandular nerve caused a pressure rise, the size of which increased with the initial pressure. This response was abolished by a small dose of atropine.

2. The effect was not due to salivary secretion, since the single stimulus caused salivation only exceptionally. Repetitive stimulation at frequencies too low to evoke secretion could produce summated pressure responses.

3. The single stimulus applied to the chorda tympani was found to cause vasodilatation in the submaxillary gland. This was abolished by a small dose of atropine, together with the pressure rise in the duct. However, repetitive stimulation still caused marked vasodilatation but no pressure response. It was therefore inferred that the pressure rise obtained before atropine was not due to vasodilatation in the gland.

4. It is concluded that the myoepithelial cells of the salivary glands are supplied with a parasympathetic motor innervation which can cause them to contract.

5. Sympathetic stimulation caused no pressure rise when a single stimulus was given but only when repetitive stimulation was used at a frequency approaching that required for secretion.
The effect of oestrogen and progesterone on the pressor action of angiotensin in the rat
Authors: Hettiaratchi E. S. G. , Pickford Mary
Published: December 2014

1. A comparison was made between the pressor responses to angiotensin in rats during different stages of the oestrous cycle, pregnancy, pseudopregnancy and also following oestrogen and progesterone treatment.

2. No evidence for an effect of oestrogen on the response to angiotensin was found.

3. Pregnancy and pseudopregnancy were found to diminish the pressor response to angiotensin.

4. Progesterone treatment also diminished the response to angiotensin.

5. It is suggested that the decrease in pressor response in pregnancy and pseudopregnancy is attributable to progesterone.

6. The possible mode of action of progesterone is discussed.
The relation between quantum content and facilitation at the neuromuscular junction of the frog
Authors: Mallart A. , Martin A. R.
Published: December 2014

1. Experiments were done on the neuromuscular junction of the frog to study facilitation of the end‐plate potential (e.p.p.) produced by one or more conditioning shocks applied to the motor nerve. Neuromuscular transmission was blocked with Mg (+)‐tubocurarine chloride.

2. In Mg‐blocked preparations, facilitation increased with increasing Mg concentrations in the range 14‐34 m
M. The increase in facilitation was related specifically to the decrease in mean quantum content of the e.p.p., and was most marked with quantum contents less than 10.

3. Facilitation in curarized preparations was similar in magnitude to that in preparations blocked with the lower Mg concentrations. Interaction between facilitation and depression in curarized preparations was consistent with the idea that facilitation was due to an increase in probability of transmitter release and depression to depletion of transmitter.
Group Ia synaptic input to fast and slow twitch motor units of cat triceps surae
Authors: Burke R. E.
Published: December 2014

1 The characteristics of the group Ia synaptic input to triceps surae motoneurones have been examined in pentobarbitone‐anaesthetized cats, using intracellular recording techniques. The mechanical properties of the muscle units innervated by the cells were determined and the motoneurone input resistance values were also measured.

2. A significant positive correlation was found between the maximum amplitudes of homonymous composite (electrically evoked) monosynaptic excitatory post‐synaptic potentials (EPSPs) and the motoneurone input resistance values across the entire population of units sampled. The same correlation in the case of heteronymous EPSPs was also significant although somewhat less strong.

3. The distribution of the amplitudes of unitary miniature EPSPs (mEPSPs) of presumed group Ia origin, elicited by small static stretches of the homonymous muscles, were also studied. A significant positive correlation was found between the median amplitudes of the mEPSP distributions and the input resistance values in the motoneurones studied. Positive correlation was also observed between the amplitudes of the median mEPSPs and the maximum homonymous composite EPSPs in the cells for which both data points were available.

4. In each of these correlations, the synaptic potential amplitudes tended to be larger in the relatively high resistance type S (slow twitch muscle unit) motoneurones from both gastrocnemius and soleus motor pools, than in the lower resistance type F (fast twitch muscle unit) gastrocnemius cells.

5. Examination of the shape of the homonymous monosynaptic EPSP wave forms in different motoneurones showed that these tended to be significantly longer in duration in type S cells than in type F. This difference could not be entirely accounted for by the relatively small difference in mean time constant values found in types F and S cells.

6. The results suggest that the density of group Ia synaptic terminals tends to be higher on type S motoneurones than on the type F cells. Further, cells receiving a relatively high density of group Ia input apparently tend to have a greater proportion of this input distributed to distal membrane regions than is the case in motoneurones receiving a relatively low input density.
Observations on the nucleolar and total cell body nucleic acid of injured nerve cells
Authors: Watson W. E.
Published: December 2014

1. The nucleic acid content of neuronal nucleoli and the total cell body nucleic acid content of neurones of the hypoglossal nucleus were measured by ultraviolet absorption microspectrography.

2. After nerve injury both the nucleolar nucleic acid and the total cell body nucleic acid increased: nucleolar changes preceded those of the cell body.

3. The closer to the nerve cell body that the axon was injured the earlier was the onset and the decline of the nucleolar response.

4. Actinomycin D was given to prevent DNA‐primed RNA synthesis, and the rate of ‘decay’ of nucleolar RNA was measured. This rate varied after nerve injury and was closely related to the nucleolar nucleic acid content.

5. The apparent rate of transfer of labelled RNA from the neuronal nucleus into the cytoplasm changed after nerve injury in a manner closely related to the changes in nucleolar nucleic acid content.

6. It was demonstrated by making consecutive nerve injuries or by preventing or delaying nerve regeneration, that the nucleic acid changes were not induced by removal of contact between the neurone and its motor end‐plate, and were not repressed by the restoration of such contact.

7. When regeneration was prevented the nucleolar nucleic acid content and the total cell body nucleic acid ultimately decreased to values less than normal: this decrease was greater when more of the axon was initially removed.

8. The results are discussed in relation to the factor responsible for derepression and repression of DNA cistrons for ribosome synthesis in injured nerve cells.
The action of ethacrynic acid on sodium efflux from single toad oocytes
Authors: Bittar E. E. , Dick D. A. T. , Fry D. J.
Published: December 2014

1. Ethacrynic acid (10−3
M) at pH 7·4 caused approximately 83% inhibition of Na efflux from single dissected toad oocytes.

2. Less inhibition was found at concentrations below 10−3
M but higher concentrations did not cause greater inhibition.

3. At an external pH of 7·0 the onset of inhibition was more rapid than at pH 7·4.

4. Ouabain (10−3
M) produced only 30% inhibition of the Na efflux, and the subsequent application of ethacrynic acid largely inhibited the remaining efflux.

5. Application of ouabain, after ethacrynic acid had produced some 80% inhibition, caused only a further 9% drop in efflux.

6. In uninhibited cells, Na efflux was found to be greater at pH 8·0, and less at pH 7·0 than at 7·4.
Action of amphotericin B on the toad bladder: evidence for sodium transport along two pathways
Authors: Bentley P. J.
Published: December 2014

1. The relationship of short‐circuit current (SCC, sodium transport) and potential difference (p.d.) across the toad bladder to the concentration of sodium on the mucosal side was measured. Maximal values were attained when the Na concentration was 10 m
M for SCC and 30 m
M for p.d.

2. Amphotericin B increased SCC across bladders bathed on their mucosal surface with isotonic (115 m
M) NaCl solution and this effect was not inhibited by cyanide and iodoacetate. The osmotic permeability of the bladder was also increased by amphotericin B.

3. Vasopressin and aldosterone increased sodium transport from solutions of low Na concentration, but amphotericin B was ineffective until a level of about 40‐60 m
M was present.

4. The evidence suggests two pathways for sodium transport across the bladder distinguished by differences in their electrochemical gradients with the fluid at the mucosal side.
The occurrence of antigen reacting with antibody to porcine neurophysin
Authors: Ginsburg M. , Jayasena K.
Published: December 2014

1. Antiserum was raised in rabbits to neurophysin prepared from posterior pituitaries of pigs. The presence of antibody reacting with porcine neurophysin was demonstrated in precipitation, gel diffusion and immunoelectrophoretic tests.

2. The antibody was species specific and did not react with protein from rat, bovine or guinea‐pig neurohypophyses.

3. The occurrence of antigen reacting with anti‐neurophysin serum was demonstrated in acetic acid extracts of porcine kidney but there was no evidence for the presence of antigen in extracts of liver or spleen prepared in the same way.

4. Protein fractions (‘N‐fractions’) from various organs and tissues of pigs were obtained by the same methods used to prepare neurophysin from posterior pituitaries and were tested for antigenicity in reaction with neurophysin antibody. N‐fractions from kidney, uterus, mammary gland and serum contained antigen while fractions from liver, spleen, brain and skeletal muscle did not react with the anti‐neurophysin serum.
The biliary‐faecal excretion of thyroxine during cold exposure in the rat
Authors: Hillier A. P.
Published: December 2014

1. The biliary‐faecal route of thyroxine excretion has been examined by means of thyroxine labelled with 131I in the thyroidectomized, thyroxine‐maintained rat during cold exposure.

2. The rate of excretion of thyroxine into the faeces is raised in rats exposed to cold for 2 weeks and fed ad libitum on a high roughage diet.

3. When the faecal volumes of warm‐ and cold‐exposed animals are made similar by controlling the roughage content of the diet the difference in their faecal thyroxine excretion rates is much reduced.

4. Warm‐ and cold‐exposed rats eating the same amount of food excrete thyroxine into their faeces at similar rates.

5. Even when warm‐ and cold‐exposed rats excrete thyroxine into their faeces at the same rate the cold‐exposed animals still show a shorter half‐life for blood thyroxine.

6. An acceleration of the rate of loss of thyroxine from the blood is demonstrable in fasting animals within 10 hr of exposure to cold.

7. Ligation of the bile‐duct does not affect this acute response to cold.

8. The amount of thyroxine lost into the bile within the first 8 hr after intravenous injection is similar in warm‐ and cold‐exposed animals. The clearance of thyroxine into the bile is however greater in the cold‐exposed animal since the liver is working against a lower level of blood thyroxine.

9. An acceleration of the biliary‐faecal route of thyroxine excretion is not the only process at work tending to reduce the biological half‐life of thyroxine during cold exposure.
Antidromic activation of the isthmo‐optic nucleus
Authors: Holden A. L.
Published: December 2014

1. This paper describes experiments carried out to record from output cells in the isthmo‐optic nucleus.

2. One‐hundred and twenty‐seven axonal responses were fired at fixed latency from the optic nerve‐head.

3. Ninety‐nine cell responses were fired trans‐synaptically from the optic nerve‐head.

4. Ninety‐four cells were activated antidromically from the optic nerve‐head.

5. Tectal tracks could be recognized by the field potential profile of the N‐wave, R‐wave and P‐wave, and by the occurrence of fixed latency axonal responses and trans‐synaptically fired cells.

6. Tectal tracks were verified histologically.

7. Tracks yielding antidromically activated cells were traced histologically to the isthmo‐optic nucleus.

8. The antidromic A‐wave could be recorded from the nucleus, corresponding in timing to the invasion of cell bodies.

9. Somatic records in the nucleus could be recognized by their duration, conformation, and A—B blocking.

10. When antidromic discharge was interacted with orthodromic firing, collision evidence could be provided, showing that the orthodromic impulse travels centrifugally to the retina.
The centrifugal system running to the pigeon retina
Authors: Holden A. L.
Published: December 2014

1. This paper describes synaptic actions upon the isthmo‐optic nucleus.

2. A synaptic field potential, the S‐wave, can be recorded from the nucleus in response to electrical stimulation of the lateral tectum. It cannot follow repetitive stimulation at rates higher than 30/sec, is depressed for long periods following the A‐wave, and shows frequency potentiation at 10/sec.

3. The majority of output cells in the nucleus are fired synaptically from the lateral tectum. The early discharge corresponds in timing to the S‐wave, and represents monosynaptic activation via the tecto‐isthmo‐optic tract. Later firing is produced by more complex routes. The early firing shows frequency potentiation at 10/sec.

4. An estimate is given of the time at which a centrifugal volley enters the retina after electrical stimulation of the lateral tectum.

5. One tenth of the output cells in the nucleus are fired synaptically from the retina. Short latency firing occurs at 5‐7 msec, and is often blocked by prior antidromic invasion. Cells are also fired synaptically at longer latency, at 80‐110 msec.

6. Antidromic invasion can be blocked by conditioning stimuli applied to the retina and to the lateral tectum.

7. It is shown that even the earliest synaptic firing from the retina could involve the serial activation of the retinotectal and the tecto‐isthmo‐optic systems.
Quantitative estimation of 17α‐hydroxypregn‐4‐ene‐3,20‐dione (17αOH‐progesterone) in adrenal venous blood and adrenal glands
Authors: Holzbauer Margarethe , Newport Helen M.
Published: December 2014

1. A method is described for the accurate estimation of small quantities of 17α‐hydroxypregn‐4‐ene‐3,20‐dione (17αOH‐progesterone) in blood and adrenal glands.

2. The dog adrenal was found to secrete 17αOH‐progesterone under conditions of operative stress at a rate of 5‐10 μg/g tissue/hr. This is similar to the secretion rate of aldosterone.

3. The secretion of 17αOH‐progesterone was decreased after hypophysectomy and increased in response to adrenocorticotrophic hormone (ACTH).

4. The adrenal gland of the dog, the monkey and the guinea‐pig was found to contain between 0·6 and 6 μg of 17αOH‐progesterone/g tissue. The concentration was usually somewhat smaller than that of pregnenolone or progesterone and between 1 and 20% of the concentrations of the glucocorticoids.

5. A comparison of adrenal steroid contents and secretion rates under conditions of stress indicates a rate of synthesis in the order of 30‐40 n‐moles of 17αOH‐progesterone/g adrenal tissue/min.
Actions of some anions on electrical properties and mechanical threshold of frog twitch muscle
Authors: Kao C. Y. , Stanfield P. R.
Published: December 2014

1. Using two micro‐electrodes in a point‐voltage clamp technique, the effects of the lyotropic anions, NO3μ−, Brμ−, Iμ−, SCNμ−, and CH3SO4μ−, and of SO42− on the mechanical threshold and electrical properties of frog sartorius muscle were studied.

2. In chloride Ringer solution the spike threshold was ‐59 mV, mechanical threshold ‐48 mV, and the threshold for delayed rectification of the total current at about 100 msec −52 mV.

3. When Clμ− was replaced by one of the lyotropic anions, the effective resistance determined at ‐100 mV tended to increase. But, because of the variability of the effective resistance in individual fibres, most lyotropic anions did not cause a statistically significant increase in the effective resistance. Only Iμ− and SO42− significantly increased the effective resistance.

4. Most lyotropic anions had no significant effect on the spike threshold; Iμ−, at 58 m
M, lowered it slightly. Sulphate raised the threshold.

5. Tetrodotoxin (0·1 μg/ml.) abolished the spikes, but did not affect the mechanical and delayed rectification thresholds. It was, therefore, used to pre‐treat all preparations for determining these thresholds.

6. All lyotropic anions lowered the mechanical and the delayed rectification thresholds, the order of effectiveness being approximately SCNμ− > Iμ− > NO3μ− > CH3SO4μ− > Brμ−. As in Clμ− Ringer, the two thresholds lay very close together in every case. Sulphate raised slightly both the mechanical and delayed rectification thresholds, again in close parallel.

7. This close agreement of the mechanical and delayed rectification thresholds is not caused by movement artifact, because in fibres in which visible contractions were eliminated with hypertonic solutions the delayed rectification thresholds were the same as those in contracting fibres.

8. In spite of the close agreement, reasons are given to doubt a direct causal relationship between the mechanical and delayed rectification thresholds.

9. Nitrate apparently had little effect on the rate of inactivation of the outward current, or on the relation between steady‐state inactivation and membrane potential.