bluuebunny/crossref_metadata_2025_split huggingface dataset:
The control by internal calcium of membrane permeability to sodium and potassium
Authors: Romero P. J. , Whittam R. 
Published: December 2014

1. A study has been made of the relationship between the concentration of internal calcium and the permeability of human red cell membranes to sodium and potassium.2. Fresh red cells contain very little calcium, but after being depleted of ATP by ageing they took up calcium from Ringer solution. The entry was unaffected by external sodium and potassium but was markedly pH dependent. When supplied with energy, calcium‐loaded cells actively extruded calcium by a saturable process which was also unaffected by the distribution of sodium and potassium across the membranes. The activity of the calcium pump was sufficient to maintain the low internal concentration found under physiological conditions.3. Raising internal calcium in metabolically poor cells caused a loss of cell potassium which was greater than the concomitant sodium gain. These changes were reversed when ATP was supplied. External calcium had no effect. The increase in permeability to sodium and potassium was enhanced by the simultaneous addition of fluoride, and, even more so, of iodoacetate. These inhibitors had no effect on membrane permeability unless calcium was also present. Inosine potentiated the action of fluoride and iodoacetate in causing potassium loss, by allowing more calcium to enter the cells.4. The results suggest that the permeability of human red cell membranes to sodium and potassium is regulated by internal calcium, which in turn is controlled by a calcium pump that utilizes ATP.
Efferent and afferent impulse activity recorded from few‐fibre preparations of otherwise intact sinus and aortic nerves
Authors: Neil E. , O'Regan R. G. 
Published: December 2014

1. In anaesthetized cats, the efferent discharge recorded from slips of otherwise intact sinus nerves was sparse in eupnoeic conditions but increased markedly during systemic hypoxia or asphyxia or following the injection of cyanide or acetaldehyde into the circulation of the ipsilateral carotid body.2. When the sinus nerve was cut distal to the efferent slip the responses to cyanide or acetaldehyde were abolished. The sparse ‘resting’ activity which remained was increased following the intravenous injection of adrenaline. Following distal section, the impulse traffic of the efferent slip did increase during systemic hypoxia but the response was much feebler than when the nerve was otherwise intact.3. The impulse activity of most efferent slips, peeled off from the otherwise intact sinus nerve, was abolished when the glossopharyngeal nerve was cut central to its junction with the same sinus nerve, indicating that the activity was probably recorded from genuine efferent units. The discharge of some ‘efferent’ preparations was still present, however, following such section and showed an increase to local injections of cyanide. This activity was probably recorded from looping or branching chemoreceptor afferents.4. The discharge of efferent slips of the cut aortic nerve was increased following the intravenous injection of adrenaline and during systemic hypoxia. These responses were not present when the vagus nerve was cut central to the nodose ganglion.5. In eupnoea, chemoreceptor afferent activity recorded from slips of the sinus or aortic nerves is much the same whether these nerves be otherwise intact or whether they be cut. During systemic hypoxia, chemoreceptor afferent discharge was less when it was recorded from the otherwise intact nerves than when these nerve trunks were cut.6. The cell bodies of sinus nerve efferent fibres are synaptically excited by chemoreceptor afferents coursing in the same nerve trunk. The increase of efferent impulse activity aroused by this means depresses chemoreceptor afferent discharge.
The dependence of the contractile force generated by frog auricular trabeculae upon the external calcium concentration
Authors: Chapman R. A. , Tunstall J. 
Published: December 2014

1. A method is described by which the solutions bathing single auricular trabeculae, isolated from the heart of the frog, can be rapidly altered while the tension generated and the membrane potential can be measured simultaneously.2. Changes of the [Ca]o result in changes of the twitch strength similar to that reported for frog ventricle.3. At [Ca]o of less than 1 m
M, the isometric contracture tension generated during application of K‐rich solutions, and the maximum rate of tension development, are proportional to [Ca]o3.4. This relationship is not the consequence of (a) the hypertonicity of the K‐rich solutions, (b) the dependence of the membrane potential on [Ca]o, or (c) the facilitation due to a twitch response at the initiation of the contracture.5. Reduction of the [Na]o increases the strength of the high‐K contractures according to the ratio of [Ca]o/[Na]o2; Na ions in the bathing medium are shown to competitively inhibit the potentiating action of Ca ions on the force generated during contractures.6. An equation is derived which assumes that three Ca compounds act co‐operatively at some stage in the process of excitation—contraction coupling.7. Two hypotheses are discussed. The first proposes that the sarcoplasmic [Ca] established during depolarization of the muscle membrane depends upon [Ca]o3, and tension generated by the contractile elements on a first order reaction with ionic Ca. The second suggests that if the sarcoplasm [Ca] established during excitation is proportional to [Ca]o, then three Ca ions are required to activate the contractile response at the unit level.
The storage of endogenous noradrenaline in sympathetic nerve terminals
Authors: Bisby M. A. , Fillenz Marianne 
Published: December 2014

1. The subcellular distribution of noradrenaline in sympathetic nerve terminals of rat vas deferens and cat spleen has been studied by cell fractionation methods combined with fluorescence and electronmicroscopic histochemical methods for noradrenaline.2. Pinched‐off axon varicosities (synaptosomes) were isolated and identified by fluorescence and electronmicroscopy in the mitochondrial pellet.3. The proportion of large to small dense‐cored vesicles in electronmicrographs of sympathetic nerve terminals varies in different organs. In rat vas deferens 4% and in cat spleen 20% are large vesicles.4. Density gradients of rat vas deferens have a single low density peak of noradrenaline at 0·6
M sucrose, whereas those of cat spleen have an additional peak of noradrenaline at 1·1
M sucrose.5. Small dense‐cored vesicles were identified electronmicroscopically in the low density fractions and large dense‐cored vesicles in the high density fractions from density gradients.6. We conclude that both small and large dense‐cored vesicles store noradrenaline.
The mechanism of excitation by acetylcholine in the cerebral cortex
Authors: Krnjević K. , Pumain R. , Renaud L. 
Published: December 2014

1. The muscarinic depolarizing action of ACh on cortical neurones is associated with an increase in membrane resistance (mean ΔV/ΔR = 3·16 mV/MΩ).2. ACh also promotes repetitive firing by slowing repolarization after spikes.3. The depolarizing effect has a mean reversal level of −86·7 mV (with mean resting potential −56 mV).4. It is concluded that as a muscarinic excitatory agent, ACh probably acts by reducing the resting K+ conductance of cortical neurones, and also the delayed K+ current of the action potential.5. These results are discussed in relation to the possible role of ACh in cortical function.
The imprecision arising from the application of the Henderson—Hasselbalch relationship to the blood of anaesthetized dogs
Authors: Linden R. J. , Norman J. 
Published: December 2014

1. Arterial blood samples were obtained from anaesthetized dogs in which either a respiratory alkalaemia, a respiratory acidaemia or a non‐respiratory acidaemia was produced and from animals in which no deliberate changes in acid—base balance were produced. The samples were analysed for pH, carbon dioxide tension and concentration, oxygen tension and concentration and haematocrit. From these determinations the plasma carbon dioxide concentration, the plasma bicarbonate ion concentration and pK′ were calculated.2. The value of pK′ lay within the range 5·86–6·27. The temperatures of the animals studied were between 36·75 and 39·25° C but there was no significant relationship between pK′ and temperature.3. The values of pK′ increased with an alkalaemia and decreased with an acidaemia.4. In addition to the variation of pK′ with pH there was a considerable residual scatter of pK′ values at any one pH value.5. It was concluded that in these experimental conditions the use of the Henderson—Hasselbalch equation in a form not dealing with activities was unacceptable and could lead to much larger errors than has hitherto been thought.
Comparison of aortic and carotid baroreflexes in the dog
Authors: Donald David E. , Edis Anthony J. 
Published: December 2014

1. Experiments with vascularly isolated, blood‐perfused aortic arch and carotid sinus preparations in sixteen dogs have provided evidence which suggests that, in the reflex regulation of normal arterial blood pressure, the aortic and carotid baroreflexes are not equivalent.2. Two different techniques were used. In one, a steel cannula was inserted into the ascending aorta and arch and fixed in position by ligatures about the aorta. The blood‐filled space (aortic jacket) thus created could be distended with known pressures; the cardiac output passed through the cannula into the descending aorta. In the other, an extracorporeal circulation utilizing an isolated heart—lung preparation was used to separately perfuse the carotid sinuses, aortic arch, and systemic circulation of a test dog.3. Independent open‐loop analysis of the aortic and carotid baroreflexes in each dog indicated that they were essentially similar in their over‐all modus operandi but that there were quantitative differences between them which would suggest a predominant role for the carotid sinus reflex in the control of normal blood pressure.4. The carotid sinus Blutdruck‐charakteristik curve was symmetrical about the range of normal blood pressure for the dog while the aortic arch curve was displaced to the right.5. The carotid sinus system had the greater gain (with reference to limb vascular resistance) and exhibited a greater maximal capacity to alter vascular resistance reflexly.6. When the carotid and aortic systems were activated simultaneously by distension, the reflex depressor responses were summed, essentially by a process of simple addition. A carotid‐induced pressor response obscured a simultaneous aortic‐induced depressor response of equal magnitude.7. In five dogs studied, the functional reflexogenic area of the aortic arch did not extend distally beyond the origin of the left subclavian artery.
Growth and reproduction of mice cross‐fostered between parents reared at different temperatures
Authors: Barnett S. A. , Neil Alexandra C. 
Published: December 2014

1. Litters of mice, Mus musculus, of the highly inbred strain A2G/Tb, were reduced to four at birth and cross‐fostered within and between three classes: (i) bred at 21° C (controls); (ii) the first generation reared at −3° C (‘new stock’); (iii) the seventeenth to twenty‐third generations reared at −3° C (‘old stock’). There were therefore nine classes of fostered mice.2. There was a higher death rate in the nest and after wearing among mice of new‐stock parentage, regardless of foster‐parentage.3. Litters reared at 21° C were heavier at 3 weeks than those reared at −3° C, regardless of parentage; the effect of temperature was also evident in body weights at 16 weeks. There was compensatory growth between 3 and 16 weeks, shown by lower variance in body weight, within classes, at 16 weeks.4. Members of fostered litters were mated, and their reproductive performance recorded to the age of 28 weeks.5. More young were born and weaned per pair at 21° C than at −3° C, regardless of true parentage. In contrast, nestling mortality depended principally on true parentage; there were fewer deaths among the young of mice whose true parents were old stock, regardless of foster‐parentage; this effect was especially evident for losses of whole litters.6. Mean body weights of the nine classes of fostered females were positively correlated with mean numbers of young born to them, and with the mean weights of their young at 3 weeks; but there was no such correlation with death rates among their young.7. Young of some of the fostered mice were also mated. The effect of old‐stock ancestry on nestling mortality was not evident in this further generation. Some mice were studied after transfer between temperatures without fostering. Their breeding performance confirmed that old‐stock mice did not retain their superiority after two generations at 21° C.8. General conclusions are: (i) differences of growth between classes of fostered mice reflected the temperature in which the mice were reared, whereas mortality among fostered mice was influenced by the conditions they had experienced in utero; (ii) the production of young by the fostered mice was influenced by environmental temperature, while the death rates among these young in the nest reflected the conditions experienced in utero by their parents.
Interaction between colour and spatial coded processes converging to retinal ganglion cells in goldfish
Authors: Spekreijse H. , van den Berg T. J. T. P. 
Published: December 2014

1. Extracellular recordings were made from ganglion cell units in the isolated goldfish retina. The discharge patterns of these units are spatial and colour coded.2. Even for weak stimuli these ganglion cell responses are highly distorted. To a first approximation a rectifying element can account for the observed distortion.3. A method is introduced to determine whether the interaction between the spatial and colour‐coded processes occurs preceding or after the rectifying stage.4. With various stimulus patterns such as checkerboards, bars, annuli, etc., not only the location of the interaction point but also the mode of operation underlying the colour and spatial interactions has been studied.5. The presented data indicate that for the common phasic ganglion cells in the goldfish retina spatial and colour interaction occurs preceding the rectifying stage. Moreover an algebraic mode of operation governs this interaction.6. The charm of the presented method lies in the fact that no assumptions need to be made about the dynamics of the various retinal transformations converging to the ganglion cells. Neither is a description required for the non‐linear (rectifying) element in order to answer the question of the location and the mode of operation of the colour and spatial interaction mechanism.
The discharge of sweat in Welsh Mountain sheep
Authors: Johnson K. G. 
Published: December 2014

1. Experiments were done on Welsh Mountain sheep to determine whether the sheep can be caused to discharge sweat continuously.2. On administration of sequences of four to eighteen
I.V. injections of adrenaline or noradrenaline (200 μg), sheep responded to the first 4‐5 injections with decreasing amounts of sweat discharge. Thereafter, the responses were fairly constant at about 10% of the first discharge. Occasionally one injection within a series elicited no sweat discharge but on other isolated occasions large discharges of sweat were induced. The blood pressure response to repeated
I.V. injections of adrenaline remained constant.3. Inhalation of amyl nitrite or rebreathing of expired air during
I.V. adrenaline injections had little effect on the pattern of intermittent sweat discharges and did not induce a continuous outflow of fluid from the sweat glands.4. Continuous infusions of adrenaline and of carbachol did not cause a change in the rate of continuous water vapour loss from the skin but possibly increased the frequency of intermittent sweat discharges.5. Electrical stimulation of the cervical sympathetic nerve for short (0·5–2 min) or long (20–30 min) periods caused only transient (3–6 min) increases in water vapour loss from the cheek skin.6. None of these experiments indicated that the sweat glands of the sheep can be induced to discharge fluid continuously.
Spino‐spinal mechanisms in the chloralose anaesthetized cat
Authors: Abrahams V. C. 
Published: December 2014

1. In chloralose anaesthetized cats the events in the lumbosacral cord that follow stimulation of a forepaw or neck nerve have been examined.2. Four events take place in the lumbosacral cord after forepaw or neck muscle nerve stimulation. These are: (1) a brief period of generalized enhanced motoneurone excitability, (2) a prolonged and as yet unexplained enhancement of monosynaptic reflexes, (3) a period of presynaptic inhibition in muscle and skin afferent fibres, and (4) a prolonged inhibition of spino‐bulbo‐spinal reflexes.3. A variable and sometimes selective reduction of one or another descending effects follows the placing of small lesions in the anterior portion of the suprasylvian gyrus.
Amino acid metabolism in the isolated perfused rat liver
Authors: Kerly Margaret , Spruyt Joy E. L. 
Published: December 2014

1. Rat livers have been perfused with homologous blood and the distribution of 15N from labelled amino acids added to the perfusate studied.2. Each of the amino acids added, aspartate, alanine, glycine, and glutamate (unlabelled) were rapidly removed from the perfusate. Glutamate was formed from added aspartate (but not from added alanine or glycine) by transamination in the perfusate plasma; the perfusate concentration of no other amino acid was affected by addition of any of the acids investigated.3. Urea output was increased by addition of aspartate, increase in output after addition of alanine or glycine was not significant.4. After addition of labelled aspartate, alanine or glycine an increase in isotope ratio was detected in urea, ammonia, glutamine, aspartate and alanine in the perfusate and, in some experiments, in the liver. After addition of alanine an increase was also detected in lysine, tyrosine, phenylalanine, methionine, proline, tryptophan and threonine+serine (analysed together).
Binocular interaction fields of single units in the cat striate cortex
Authors: Bishop P. O. , Henry G. H. , Smith C. J. 
Published: December 2014

1. Based on average response histograms to an optimal stimulus, binocular interaction field plots were obtained from twenty‐five simple neurones in the striate cortex of the cat. Each binocularly activated cell has two interaction fields, one for each eye. The binocular interaction field for one eye plots the changes in the amplitude of the response from the other eye as the two receptive fields of the binocularly activated cell are moved across one another, first into and then out of alignment in the plane of the optimal stimulus (tangent screen).2. The binocular interaction field provides an important clue to the nature of the spatial organization of the excitatory and inhibitory regions of the monocular receptive field. The commonest type of receptive field organization has regions of inhibition (inhibitory side bands) to either side of the discharge centre in the direction at right angles to the optimal stimulus orientation. As well as inhibition, there are subliminal excitatory effects.3. Binocular interaction fields differ with the various cell types, i.e. cells that are discharged only from the one eye, cells binocularly discharged with very weak or absent monocular responses and cells showing binocularly opposite direction selectivity.4. Marked facilitation to an optimal stimulus occurs when the two receptive fields of a binocularly activated neurone are in accurate alignment. Facilitation switches to depression for very small degrees of receptive field misalignment in a direction at right angles to the optimal stimulus orientation. These observations are of importance in relation to mechanisms for binocular single vision and depth discrimination.
Sex differences in the changes in sympathetic nerve activity when arterial pressure is raised by infusion of angiotensin and noradrenaline
Authors: Morrison J. F. B. , Pickford Mary 
Published: December 2014

1. In cats and dogs impulse frequency was studied in single and few‐fibre preparations of the cervical sympathetic nerves when blood pressure was raised in steps to about 200 mm Hg by infusions of noradrenaline and angiotensin. Two forms of frequency/blood pressure relationships were found which differed in their distribution between the sexes.2. In females, both normal and ovariectomized, there was an inverse linear relationship between spike frequency and blood pressure over the whole range of blood pressure studied. The same was true in castrated males and normal males pretreated with oestrogens.3. In normal males the inverse linear relationship held to a pressure of about 150 mm Hg. At higher pressures the sympathetic discharge rate remained steady or increased. This was also found in castrated males pretreated with testosterone. There was a statistically significant difference between the responses of these animals and those of normal females and castrated or oestrogen treated males.4. The sex difference originates peripherally since the responses of both sexes were similar following baroreceptor and chemoreceptor denervation. During ventilation with oxygen instead of air the male pattern of response becomes like that of the female. The latter observation implicated the chemoreceptors.5. α adrenoceptor blockade with phenoxybenzamine and phentolamine localized to the region of the carotid bifurcation in male cats abolished the increase in sympathetic discharge rate at high blood pressure induced by noradrenaline, but did not alter the response to angiotensin.6. Records of spike frequency in single and few‐fibre preparations of chemoreceptor units in the sinus nerves of cats also showed an inverse relationship between frequency and blood pressure in females. In males at the higher pressures, the discharge rate was steady or increased. The increased chemoreceptor discharge at high pressures in males was abolished by ventilation with oxygen instead of air.7. The sex difference in behaviour of chemoreceptor units could not be explained by differences in either total carotid body blood flow or arterial oxygen tension.8. It is tentatively concluded that the observed sex difference is related to the state of the blood supply to the chemoreceptors and that, in males, testosterone sensitizes the blood vessels to vasoconstrictors, so that at high pressures blood is diverted through shunts and the chemoreceptors are subjected to a stagnant hypoxia.
Pepsin secretion, gastric motility and mucosal blood flow in the anaesthetized cat
Authors: Reed J. D. , Sanders D. J. 
Published: December 2014

1. There is a weak relationship between pepsin output and gastric mucosal blood flow (MBF) during vagal stimulation. When compared with the strong relationship between H+ output and MBF, this suggests little dependence of pepsin secretion on MBF.2. Gastric MBF per unit H+ output was significantly greater during vagal stimulation, when H+ secretion was accompanied by pepsin secretion, than during pentapeptide stimulation when no pepsin was secreted.3. Pepsin output was not reduced during splanchnic stimulation whereas MBF and acid output were, when blood pressure was kept constant.4. Splanchnic stimulation did not produce any pepsin secretion.5. Gastric motor responses to vagal stimulation and to
I.A. injections of acetylcholine were equally reduced by splanchnic stimulation.