bluuebunny/crossref_metadata_2025_split huggingface dataset:
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.
Motor innervation of the coronary arteries of the cat
Authors: Brown A. M. 
Published: December 2014

1. The effect on coronary vascular resistance of selective stimulation of the Aδ, B and sC fibre groups of the post‐ganglionic cardiac sympathetic nerves was studied. The main left coronary artery was perfused at constant flow. The oxygen saturation of coronary sinus blood was measured continuously.2. Stimulation of the peripheral ends of the cut Aδ afferent fibres, normally excited by myocardial ischaemia, had no effect on coronary vascular resistance; these fibres do not evoke an axon reflex in the heart.3. Stimulation of the preganglionic B fibres that run without synapse through the stellate ganglion also had no measurable effect on coronary resistance.4. Stimulation of the post‐ganglionic sC fibres of the cardiac sympathetic nerves caused coronary vasodilatation which occurred earlier than, and was initially independent of the decrease in coronary sinus oxygen saturation.5. The injection of noradrenaline into the perfusion system had the same effect as stimulation of the sC fibres. In the K+‐arrested heart, both noradrenaline and stimulation of the post‐ganglionic nerves elicited coronary vasodilatation without changing the oxygen saturation of coronary sinus blood.6. The intracoronary injection of acetylcholine caused coronary vasodilatation followed by an increase of coronary sinus oxygen saturation.7. Vagal stimulation caused brady cardia and a fall in coronary resistance.8. Propranolol blocked coronary vasodilatation elicited by sympathetic stimulation or noradrenaline without affecting the vasodilatation due to myocardial ischaemia or acetylcholine. Atropine blocked coronary vasodilatation evoked by acetylcholine without affecting that due to ischaemia or noradrenaline. Therefore smooth muscle of the coronary arteries has at least three different receptor sites from which vasodilatation can be elicited.9. Hypertensin caused coronary vasoconstriction.10. The presence of sympathetic cholinergic vasodilator fibres innervating the coronary arteries could not be demonstrated.
The effects of insulin on the new‐born calf
Authors: Comline R. S. , Edwards A. V. 
Published: December 2014

1. The normal variations in the concentrations of glucose, fructose and lactic acid in the blood of the calf which occur during the first few weeks after birth have been examined.2. The responses of calves of different ages to intravenous injections of insulin have been examined by recording both the incidence of convulsions and the changes in the concentration of glucose, fructose and lactic acid in the blood.3. New‐born calves rarely convulsed during prolonged and severe hypoglycaemia and, if convulsions occurred, the onset was delayed by 6‐8 hr. At 7 days of age convulsions usually followed the injection of insulin within 1½‐2 hr.4. No relationship could be found between the duration of hypoglycaemia and the incidence of convulsions at different ages. Hypoglycaemia was most prolonged in new‐born calves which rarely convulsed.5. Insulin hypoglycaemia during the first 24 hr after birth was associated with a rise in the concentration of lactate in the blood. Similar changes did not occur in calves at 7 days of age, in which the incidence of convulsions was much higher, or in weaned animals.6. After both splanchnic nerves had been cut, insulin always caused convulsions in 24‐hr‐old calves. There was no rise in the blood lactate concentration in these animals.7. Intravenous infusions of adrenaline but not noradrenaline in amounts similar to those known to be released from the adrenal medulla of the calf of this age prevented convulsions in 24‐hr‐old calves after section of the splanchnic nerves. These infusions had little effect on the blood glucose concentration but caused a similar rise in the lactic acid concentration to that found in normal animals at this age during hypoglycaemia.8. At 7 days of age convulsions could only be prevented during hypoglycaemia by infusing larger doses of adrenaline which significantly raised the blood glucose concentration. The increase in the blood lactate concentration was less than that in the new‐born animals.9. The resistance to insulin hypoglycaemia which occurs immediately after birth is transient; it depends upon the release of adrenaline from the adrenal medulla and is associated with high concentrations of lactate in the blood during hypoglycaemia.