bluuebunny/crossref_metadata_2025_split huggingface dataset:
Respiratory function during thermal tachypnoea in sheep
Authors: Hales J. R. S. , Webster M. E. D. 
Published: December 2014

1. Four Merino wethers were exposed to dry bulb temperatures ranging from approximately 20 to 60° C, and the concurrent changes in respiratory frequency, tidal volume, respiratory minute volume, alveolar ventilation, dead space ventilation, carbon dioxide output, rectal temperature, and arterial and mixed venous blood, CO2 content, CO2 partial pressure and pH were established.2. The respiratory response to heat exposure showed two phases. Respiratory minute volume was initially increased by a rise in the respiratory frequency, while tidal volume decreased. After more prolonged exposure there was a second phase in which respiratory minute volume was further increased by an increase in the tidal volume; respiratory frequency was now slower than in the first phase but was still well above control values.3. The increase in respiratory minute volume during the first phase of the response was restricted almost entirely to the respiratory dead space; changes in blood CO2 and pH were slight. In the second phase, respiratory minute volume showed a much greater increase, and a change of alveolar ventilation to about 5 times the control level resulted in severe respiratory alkalosis.4. Contrary to findings in cattle, the slower, deeper form of respiration could be elicited even with rectal temperature in the normal range. This change in respiration appears to be the result of either peripheral thermoreceptor function or mechanical demands of the respiratory system. The neglect of control of acid—base balance during the second phase indicates the existence of a dominant thermal stimulus or modification of respiratory control mechanisms.
Gastric secretion during pregnancy and lactation in the rat
Authors: Lilja B. , Svensson S. E. 
Published: December 2014

1. Gastric acid secretion has been studied in the rat before, during and after pregnancy using different types of stomach preparation. During the same periods the histamine‐forming capacity (HFC) has been determined in gastric mucosa and mammary gland.2. In rats with a whole stomach fistula interdigestive acid secretion is increased during pregnancy and lactation.3. In rats with a denervated chronic pouch secretory response to stimulation with gastrin and histamine is augmented during pregnancy and lactation.4. The histamine forming capacity (HFC) of the gastric mucosa is increased 2‐3 times during the last days of pregnancy and also during lactation.5. The HFC of the mammary gland is increased 2‐3 times during lactation as compared with the fully developed gland in pregnancy.
The use of a non‐ionic detergent (Triton WR 1339) to determine rates of triglyceride entry into the circulation of the rat under different physiological conditions
Authors: Otway Sheila , Robinson D. S. 
Published: December 2014

1. The concentration of triglyceride in the plasma rises linearly for 3 hr after the intravenous injection of the non‐ionic detergent, Triton WR 1339, in the rat.2. Minimum rates of triglyceride entry into the plasma have been calculated from measurements of the plasma triglyceride concentration at 1·5 hr after Triton injection. These are 30 and 52 μmoles/hr.200 g body weight respectively for male and female animals on a stock laboratory diet and 25 and 33 μmoles/hr.200 g body weight respectively for male and female animals starved for 48 hr. The values may have to be increased by 10 or 20% to take account of a small leak of triglyceride from the plasma in animals injected with Triton and of an effect of ether anaesthesia on the rate of entry of triglyceride into the plasma.3. Substitution of the stock laboratory diet by diets that are lower in fat content does not alter significantly the rate of triglyceride accumulation in the plasma after Triton injection.4. There is no change in the triglyceride content of the livers of male and female rats at 24 hr after Triton injection. At 6 hr after Triton, the liver triglyceride content of female rats which have been fed their normal diet is increased.
Water uptake by Bufo melanostictus, as affected by osmotic gradients, vasopressin and temperature
Authors: Dicker S. E. , Elliott Annie B. 
Published: December 2014

1. The rate of water uptake across the skin was studied in the live toad, Bufo melanostictus. When toads were kept in distilled water at 29° C the uptake of water amounted to 16·9 ± 1·3 μl./cm2/hr; when bathed in sucrose or urea solutions, the water uptake diminished with increasing osmotic pressure. There was no water uptake observed when toads were kept in 200 m‐osmolar sucrose or urea.2. Intramuscular injections of vasopressin increased the rate of water uptake from distilled water. There was a good relation between doses and responses over various time intervals. A dose of 4 m‐u. vasopressin/g body wt. doubled the rate of water uptake over a period of 1 hr. The same dose of vasopressin doubled the rate of water uptake when the toads were kept in solutions of sucrose or urea of different osmolarity.3. The rate of water uptake when the toads were bathed in sodium chloride solutions was consistently 8 μl./cm2/hr greater than when bathed in sucrose or urea solutions of equal osmolarity. There was no water uptake when the sodium chloride solution was 285 m‐osmolar.4. Vasopressin (4 m‐u./g) injected intramuscularly doubled the rate of water uptake from sodium chloride solutions of different osmolarity.5. With solutions of potassium chloride, sodium nitrate, and potassium nitrate, in concentrations up to 150 m‐osmoles/l., the rate of water uptake was found to be the same as with solutions of sodium chloride of the same osmolarity. Similarly, it was doubled by injection of vasopressin (4m‐u./g).6. The effect of temperature on the rate of water uptake before and after injection of vasopressin was investigated in toads kept in distilled water, sucrose, or sodium chloride solutions. For temperatures between 20 and 37° C, vasopressin (4 m‐u./g) reduced the activation energy involved in the process of water uptake by 4000 cal.7. The results agree with the view that water uptake follows a diffusion process which is facilitated by vasopressin, possibly as a result of increasing the size or number of available pores.
The margin of safety of neuromuscular transmission
Authors: Paton W. D. M. , Waud D. R. 
Published: December 2014

1. The margin of safety for neuromuscular transmission in the tibialis and sartorius muscles of the cat has been determined by measuring the ratio by which end‐plate depolarization produced by succinylcholine, decamethonium, octamethonium or iodocholine is antagonized, in the presence of neuromuscular block produced by tubocurarine, gallamine or DF‐596. The estimate of the margin of safety was independent of the particular drugs chosen for the measurement.2. To produce threshold block to indirect stimulation once every 10 sec, a fractional occupancy by the antagonist of 0·76 ± 0·05 (
S.D.) was required; for nearly complete block, an occupancy of 0·917 ± 0·16 (
S.D.) was required. These figures correspond to factors of safety of 4·1 and 12 for the most sensitive and the most resistant groups of fibres respectively.3. The interaction between the agonists and the antagonists, when tested over a wide range of dosage, did not conform with the conditions of full competitive equilibrium. It was concluded that this arose, not because of some interfering non‐competitive process, but because, during the relatively brief exposure to agonist, the equilibrium between the antagonist and the receptors is not significantly disturbed. An analysis of this condition of quasi‐equilibrium is given. A correction downwards of the direct estimates of the margin of safety is required, but this proves to be small, about 8%, and may not be significant.4. The safety factor diminished when the motor nerve had been cut more than 5 hr; it is suggested that this represents an early sign of nerve degeneration.5. With dog sartorius muscle, results similar to those in the cat were obtained. But for deep block in the rabbit, the safety factor was only about 4.6. The existence of a substantial margin of safety influences considerably the interpretation of the time course of action of blocking drugs, and of comparisons between responses to nervous excitation and drug injection.
The effect of water diuresis on electrolyte excretion in unanaesthetized dogs
Authors: Coxon R. V. , Ramsay D. J. 
Published: December 2014

1. The relation between water loading and electrolyte excretion in dogs fed on a meat diet proved impossible to evaluate owing to the large variability in electrolyte excretion rates in control experiments.2. In animals fed a synthetic diet of constant and known composition the administration of a water load of 2·5% of body weight caused significant increases in the rate of excretion of sodium (P < 0·01) and potassium (P < 0·05). The chloride excretion rate also increased in the one animal tested.3. The significance of these results is discussed.
The effect of thyrocalcitonin on blood—bone calcium equilibrium in the perfused tibia of the cat
Authors: Macintyre I. , Parsons J. A. , Robinson C. J. 
Published: December 2014

1. In the isolated tibia of the cat, perfused with blood from its own carotid connected to popliteal artery via a pump, infusion of porcine thyrocalcitonin causes an arteriovenous difference in calcium concentration of up to 5%, corresponding to net retention of calcium in bone.2. When taken in conjunction with determinations of radiocalcium clearance in the tibia, the effect is of the right order of magnitude to account for the hypocalcaemic action of thyrocalcitonin in the whole animal.3. Calcium retention was accompanied by a small increase in acidity of outflowing venous blood whereas verification of the hypothesis of calcium regulation by pH change in the bone substance would require a decrease.
Cortical responses to paired stimuli applied peripherally and at sites along the somato‐sensory pathway
Authors: Angel A. 
Published: December 2014

1. Experiments have been performed on animals anaesthetized with various anaesthetics to determine the responsiveness of the cortex to the second of a pair of identical stimuli applied at three sites along the sensory pathway, i.e. to the periphery, the medial lemniscus and to thalamocortical fibres.2. It has been found that in deeply anaesthetized animals the mass response recorded from the cerebral cortex to the second of a pair of peripheral or lemniscal stimuli became reduced in size if the interval between the stimuli was 30‐500 msec. If the interval was less than 30 msec for peripheral stimuli or between 10 and 30 msec for lemniscal stimuli responses were not obtained to the second stimulus. This was found to be a basic pattern which could be modified in animals less deeply anaesthetized. In these animals, periods of relatively increased responsiveness were seen after peripheral stimulation.3. The post‐synaptic responses recorded from the ventrobasal thalamus showed the same behaviour to the second of a pair of peripheral stimuli as did the cortex both as regards size and latency of the responses.4. The post‐synaptic responses recorded from the cuneate nucleus rarely showed any reduction in size unless the separation between the stimuli was 10 msec or less; even at intervals as low as 3 msec there was no increase in the latency of the response.5. When a pair of stimuli were applied to thalamocortical fibres, a different pattern of cortical responsiveness was found. At the time the cortical response to stimulation at pre‐thalamic sites was reduced or abolished, the response to stimulation at post‐thalamic sites was unaltered or increased in size.6. Finally an attempt was made to correlate the mass response recorded from the cortical surface and the activity of single cortical cells. Two types of cell could be distinguished in the rat. Those lying from 0·35 to 1·2 mm deep in the cortex showed a response pattern, to paired stimuli, closely resembling that of the cortical mass response. Others situated deeper in the cortex were found which had a very long absolute unresponsive time, from 50 to 80 msec and a very long relative unresponsive time of 1 sec.
The effects of stimulation of the hepatic nerves, infusions of noradrenaline and occlusion of the carotid arteries on liver blood flow in the anaesthetized cat
Authors: Greenway C. V. , Lawson Anne E. , Mellander S. 
Published: December 2014

1. In anaesthetized cats, the hepatic artery, portal vein and inferior vena cava pressures and the hepatic artery and portal vein flows were recorded using pressure transducers and electro‐magnetic flowmeters.2. The hepatic nerves were stimulated with maximal stimuli for periods of 2‐5 min. The magnitude of the response varied with the frequency of stimulation over the range 1‐10 impulses/sec. The resistance to flow increased in both the hepatic artery and the portal vein.3. In the hepatic artery, mean pressure remained virtually constant, while the flow showed an initial marked decrease followed by a return towards the control level. In the portal vein, the flow remained constant while portal pressure showed a maintained increase. These responses were unaffected by previous administration of atropine and propranolol, but were blocked by phenoxybenzamine.4. Infusions of noradrenaline into the hepatic artery produced changes similar to those following stimulation of the nerves. In contrast, when the hepatic arterial pressure was maintained constant, intravenous infusions of noradrenaline produced a maintained decrease in hepatic artery flow.5. The occurrence of autoregulation of the hepatic artery flow at arterial pressures above 80‐100 mm Hg was confirmed.6. Occlusion of the carotid arteries caused a rise in arterial pressure with little change in hepatic artery flow, but when the hepatic artery pressure was maintained at the pre‐occlusion level the flow showed an abrupt decrease, usually followed by a recovery towards the control level. This decrease was abolished by section of the hepatic nerves and removal of the adrenal glands.7. It is concluded that the increase in hepatic artery resistance during occlusion of the carotid arteries was dependent on the hepatic nerves, the adrenal medullary secretions and an intrinsic autoregulatory mechanism.
Pulmonary vasoconstriction and changes in heart rate during asphyxia in immature foetal lambs
Authors: Campbell A. G. M. , Dawes G. S. , Fishman A. P. , Hyman A. I. 
Published: December 2014

1. The effect of changing the composition of pulmonary arterial blood on the pulmonary vasoconstrictor response to asphyxia was studied in immature foetal lambs of ∼ 90 days gestation age.2. When normal foetal carotid arterial blood (withdrawn before asphyxia) was introduced during asphyxia, the pulmonary vasoconstriction was rapidly and wholly relieved as soon as this blood reached the lung. This did not happen when blood was used which had been withdrawn during asphyxia.3. Conversely introduction into a pulmonary artery of a foetal lamb during recovery, of arterial blood withdrawn during asphyxia, caused an immediate return of pulmonary vasoconstriction.4. These phenomena could not be explained by the generation of vasodilator agents such as bradykinin, acetylcholine, histamine or isoprenaline.5. During asphyxia injection of normal foetal arterial blood into the left atrium did not cause pulmonary vasodilatation, but did elicit a large increase in heart rate.6. Neither the pulmonary vasoconstriction during asphyxia, nor its relief by normal foetal arterial blood, nor the changes in heart rate were affected by previous bilateral vagotomy or administration of atropine or hexamethonium.7. It was concluded that, in immature foetal lambs, the effect of asphyxia in causing pulmonary vasoconstriction was mainly, if not exclusively, by a local action within the lungs, and that the bradycardia during asphyxia was mainly due to the fall in PO2 acting locally upon the heart.
The incorporation of inorganic phosphate into adenosine triphosphate by reversal of the sodium pump
Authors: Garrahan P. J. , Glynn I. M. 
Published: December 2014

1. Resealed ghosts were prepared containing much potassium, very little sodium, and adenosine triphosphate (ATP), adenosine diphosphate (ADP) and 32P‐labelled orthophosphate (Pi) at concentrations such that the ratio [ATP]/([ADP].[Pi]) was low. Iodoacetate, iodoacetamide or both were also present. The ghosts were incubated in high‐sodium, potassium‐free media with and without ouabain, or in high‐potassium media, and the incorporation of 32P into ATP and ADP in 15 min was measured.2. There was some incorporation of 32P into the nucleotides whatever the medium, possibly because of the residual activity of glycolytic enzymes, but in every experiment there was extra incorporation when the ghosts were in a high‐sodium, potassium‐free medium. This extra incorporation was largely abolished by ouabain (5 experiments) and partly abolished by oligomycin (1 experiment).3. It seems that if conditions are such that the over‐all reaction associated with transport ATPase activity leads to an increase in free energy, the transport system will run backwards at a measurable rate and ATP will be synthesized at the expense of energy derived from ionic concentration gradients.4. The nature of the transport system is discussed in the light of the findings of this paper and the four preceding papers.
The effect of chromatic aberration on visual acuity
Authors: Campbell F. W. , Gubisch R. W. 
Published: December 2014

1. Differences of threshold contrast are predicted from optical theory for a grating acuity target in monochromatic and white light. The greatest differences, up to 65%, are predicted for gratings of lower contrast and pitch than those normally used in measurements of visual acuity.2. Using three subjects, we measured contrast thresholds with 1·5 and 2·5 mm diameter artificial pupils for natural and paralysed accommodation, using a tungsten lamp and wave‐lengths of 546 and 578 mm.3. Excellent agreement is obtained between predicted and measured differences.4. Results confirm that observed acuity and sensitivity differences between white and monochromatic lights are largely optical in origin, but involve at least two independent colour mechanisms as spectral weighting functions. Stiles's π4 and π5 sensitivities afford a much better fit to observed differences than the C.I.E. visibility curve.
Spontaneous synaptic potentials and quantal release of transmitter in the stellate ganglion of the squid
Authors: Miledi R. 
Published: December 2014

1. Several kinds of synapses have been studied in the stellate ganglion of the squid.2. A small electric coupling was found between giant fibres in different stellar nerves.3. Post‐synaptic potentials recorded from the cells of small axons are composite, indicating that there are converging inputs from several pre‐ganglionic fibres.4. Spontaneous miniature synaptic potentials were recorded from all types of synapses. Miniature potentials in the cells of small axons had a slower time course than those in the giant fibre system.5. Tetrodotoxin abolished nerve impulses in the ganglion but did not prevent the spontaneous quantal release of transmitter from the terminals, or its action on the post‐synaptic membrane; nor did it prevent the increase in rate of release produced by depolarization of the presynaptic fibre.6. Glutamate depolarized the giant fibre when applied iontophoretically to the synaptic region. Similar doses applied intracellularly were without effect.
The generation and spread of S‐potentials in fish (Cyprinidae)
Authors: Naka K. I. , Rushton W. A. H. 
Published: December 2014

1. S‐potentials from Luminosity‐units in the excised eye of the tench (Tinca) were excited by white lights of various intensities and spatial distributions.2. When a small light spot of fixed size and intensity was presented at various distances from the recording electrode, the S‐potential was found to suffer an exponential attenuation with distance (Fig. 3).3. A circular patch of light centred upon the electrode and varied in radius gave concordant results.4. The effects at the electrode site of a distant light flash was not due to light scattered to the electrode which acted upon the retina there; the light acted locally and it was the current that spread.5. With red and blue light stimuli superposed on the retina, it is the potentials not the lights that add.6. These experimental results seem to indicate that S‐potentials can spread laterally across the retina within a thin layer at about the horizontal cell level.7. The layer is bounded by leaky membranes which appear to be electrogenic, no doubt as a result of transmitters released by light which change the permeability. Electric currents have no demonstrable effect.8. Two simple results were found. (a) The membrane contains an element whose conductance is proportional to the light intensity. (b) The S‐potential is a hyperbolic function of light intensity.9. All these experimental results can be explained quantitatively in terms of the formal model of Fig. 8F. But the required change of membrane permeability with light has not yet been demonstrated.
The content and localization of catecholamines in the carotid labyrinths and aortic arches of Rana temporaria
Authors: Banister R. J. , Portig P. J. , Vogt M. 
Published: December 2014

1. The catecholamine content of the carotid labyrinth of Rana temporaria was estimated by two different methods, and compared with that of the aortic arch. In both tissues adrenaline was found as the dominant amine, with traces of dopamine and noradrenaline detectable in the labyrinth only.2. Per gram of fresh tissue, the labyrinth usually contained more adrenaline than the aortic arch.3. On microscopic examination, the aortic arch was found to contain nerve fibres which fluoresced after treatment with formaldehyde, whereas within the carotid labyrinth the formaldehyde‐induced fluorescence was localized in the cytoplasm of clusters of small cells. This fluorescence resembled that exhibited by glomus cells in the mammalian carotid body.
The motor innervation of the rat urinary bladder
Authors: Carpenter F. G. , Rubin R. M. 
Published: December 2014

1. The post‐ganglionic nerves visible in silver‐impregnated sections of a normal rat bladder were absent 14 days after both pelvic ganglia had been ablated. After ablation of one ganglion the distribution of nerve trunks in either side of the organ was unchanged. Post‐ganglionic axons from either side appear to distribute bilaterally.2. The acetylcholine (ACh) content of the rat bladder was reduced from control by 50% after the post‐ganglionic nerves from one ganglion had degenerated. However, the ACh content in the two halves of the bladder sectioned along the mid line was the same after one nerve had degenerated.3. Motor responses of bladder preparations elicited during stimulation of both pelvic nerves were compared with responses elicited when each nerve was stimulated separately. In three‐quarters of the animals the sum of the individual responses exceeded the response to combined nerve stimulation by no more than 20%. The functional overlap between the two groups of motor nerves to the bladder was therefore no greater than this amount in most animals.4. Motor responses of normally innervated bladder preparations elicited in vitro by transmural stimulation were compared with responses elicited after the post‐ganglionic innervation from one side had degenerated. The mean response of bladders with half their innervation was 50‐65% of the mean response of bladders normally innervated. The functional overlap by the two groups of nerves was found to be no greater than 15%.