bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of changes of ionic environment on the negative after‐potential of the spike in rat uterine muscle
Authors: Ohashi H. 
Published: December 2014

1. The spontaneous activity of the smooth muscle of rat uterus consists of bursts of spikes, each spike being followed by a negative after‐potential. The effect of changes in ionic environment on the negative after‐potential was investigated at various stages of pregnancy and in the non‐pregnant condition.2. The amplitude of the negative after‐potential was the same in spontaneously generated and electrically evoked spikes. During repetitive discharge, whether spontaneous or in response to depolarizing current application, the amplitude of the after‐potential was smallest in the first spike of a burst and it increased gradually with repetition of discharge.3. The decay of the negative after‐potential was slower than the passive return of the membrane potential to its resting level.4. The amplitude of the negative after‐potential was larger in non‐pregnant uterus than during late pregnancy.5. In pregnant uterus, the replacement of the Cl in the medium with benzene sulphonate transiently augmented the negative after‐potential and then gradually reduced it. Eventually, the negative after‐potential disappeared and, instead, a positive after‐potential was observed. This conversion took place without a noticeable change in the resting potential or in the initial falling phase of the action potential itself. Replacement of Cl with NO3 had no appreciable effect on the negative after‐potential.6. In non‐pregnant uterus, the conversion of the negative to a positive after‐potential was never observed. However, in Cl‐deficient solution the size and duration of the negative after‐potential were reduced.7. In Cl‐deficient solution (benzene sulphonate substitution), the decay of the electrotonic potential following the break of cathodal current became faster than that in normal solution. On the other hand the development of the anodic electrotonic potential became slower.8. Replacement of the NaCl in the medium with sucrose converted the negative after‐potential to a positive after‐potential. On the other hand, reduction of Na only by replacement of NaCl with Tris‐Cl had no noticeable effect on the negative after‐potential.9. It is concluded that the negative after‐potential of the spike in rat uterine muscle is largely due to an increase of Cl conductance of the membrane.
Alterations of synaptic action in chromatolysed motoneurones of the cat
Authors: Kuno M. , Llinás R. 
Published: December 2014

1. Monosynaptic EPSPs in lumbosacral motoneurones undergoing chromatolysis were studied by intracellular recording from 7 to 20 days after section of the appropriate ventral roots of the cat.2. The maximum monosynaptic EPSPs evoked in chromatolysed motoneurones by afferent volleys from the biceps‐semitendinosus or the triceps surae muscles ranged from 1·0 to 9·5 mV in amplitude. The time‐to‐peak of these EPSPs was 1·7 msec on the average. These values were significantly smaller and longer, respectively, than the amplitude and the time‐to‐peak of monosynaptic EPSPs observed in normal motoneurones. The long time‐to‐peak of EPSPs in chromatolysed motoneurones could not be accounted for by asynchronous transmitter release.3. The mean number of unit EPSPs responding to a single afferent impulse (m) in chromatolysed motoneurones was comparable to that found in normal motoneurones.4. The amplitude of unit EPSPs estimated from the mean EPSP amplitude and the m value following stimulation of a single afferent fibre was significantly smaller in chromatolysed motoneurones than in normal motoneurones. This difference was attributed to a difference in synaptic location.5. The shape of monosynaptic EPSPs evoked in chromatolysed motoneurones by stimulation of single afferent fibres was analysed on the basis of Rall's compartment model. The analysis suggested that there is a lack of the excitatory synaptic input to the cell body in chromatolysed motoneurones.6. Similar alterations were also found in IPSPs. The degree of change in synaptic responses evoked by stimulation of various pathways appears to depend on the synaptic location.7. Following the study of the interaction of several inputs on the motoneurone and of their dependence on membrane potential, a tentative model of the synaptic distribution of different pathways is proposed.
Osmosensitive single neurones in the hypothalamus of unanaesthetized monkeys
Authors: Hayward James N. , Vincent Jean D. 
Published: December 2014

1. We recorded with tungsten micro‐electrodes the activity of single neurones in the supraoptic nucleus (NSO) and adjacent regions of the hypothalamus while repeatedly injecting solutions of varying tonicity into the common carotid artery of trained, unanaesthetized monkeys who accepted the experimental restraints without anxiety.2. Intracarotid injections of mildly hypertonic solutions of sodium chloride produced a characteristic behavioural response during and immediately after injection: e.e.g. ‘arousal,’ lip and tongue smacking, chewing, irregular sniffing respiration and associated mildly increased movement of face, eyes and body.3. Of the 130 cells analysed during hypertonic intracarotid injections, 105 (81%) were osmosensitive. Twenty‐five (19%) of the cells studied during similar injections were non‐osmosensitive. On the basis of the anatomical location of the cells, the pattern of discharge to intracarotid osmotic stimuli and the response to arousing sensory stimuli, we divided the osmosensitive cells into two major groups, ‘specific’ and ‘non‐specific’ osmosensitive cells.4. Fifty‐two (50%) of the osmosensitive cells we labelled ‘specific’ because they responded to an intracarotid injection of hypertonic sodium chloride, generally did not respond to non‐noxious arousing sensory stimuli and were located in or near the supraoptic nucleus. We found two subtypes of these ‘specific’ osmosensitive cells: (a) twenty‐one (20%) NSO cells with ‘biphasic’ responses, that is, acceleration followed by inhibition; (b) thirty‐one (30%) cells in the immediate perinuclear zone of the NSO with ‘monophasic’ responses, subdivided into twenty‐one (20%) cells that accelerated and ten (10%) that were inhibited.5. Fifty‐three osmosensitive cells (50%), located diffusely in the anterolateral hypothalamus, were ‘non‐specific’, responding both to intracarotid injections of hypertonic sodium chloride and also to sensory stimuli that were mildly arousing. Two groups of ‘non‐specific’ osmosensitive cells showed monophasic responses; thirty‐five (34%) cells accelerated and seventeen (16%) of them were inhibited.6. The ‘monophasic’ specific osmosensitive neurones lying in the immediate perinuclear zone of the supraoptic nucleus in the primate could conceivably be the ‘osmoreceptors’ of Verney. The ‘biphasic’ specific osmosensitive neurones in the NSO may well represent the secretory cells of this system. From our data, the ‘non‐specific’ osmosensitive neurones, scattered diffusely in the anterolateral hypothalamus, have little to do with osmoregulation. Some of these cells located in the perinuclear zone of the NSO could act as interneurones, however, conveying afferent input to the osmoreceptor‐secretory complex of the supraoptic nucleus.
Variations in deep body temperature in the young unrestrained pig over the 24 hour period
Authors: Ingram D. L. , Legge K. F. 
Published: December 2014

1. The temperature near the carotid artery has been measured in the unrestrained pig by means of radiotelemetry. When the animals were housed singly under constant conditions of temperature and lighting the temperature rhythm appeared to be related only to the time of feeding. A similar record was obtained from temperature measurements made in the hypothalamus.2. Over the range of ambient temperatures 10–30° C the mean body temperature was 38·8° C. No consistent variation occurred with ambient temperature, but on initial transfer from 10 to 30° C ambient temperature the body temperature decreased, while on initial transfer from 30 to 10° C it increased.3. When one pig was housed in a hut with a small outside yard a nychthemeral rhythm was sometimes superimposed on that imposed by feeding. When two pigs were kept in a paddock containing a hut the nychthemeral rhythm was more pronounced.4. It is concluded that in the pig there is very little innate circadian temperature rhythm and that the temperature variations seen are related chiefly to feeding and activity.
The localization of pupilloconstrictor function within the mid‐brain of the cat
Authors: Sillito A. M. , Zbrożyna A. W. 
Published: December 2014

1. Electrical stimulation techniques have been used to examine the localization of pupilloconstrictor function in the mid‐brain of the cat.2. The results show the preganglionic pupilloconstrictor neurones to be localized to a discrete part of the small celled component of the oculomotor nucleus.3. The area described comprises both the Edinger—Westphal and anteromedian nuclei at the level where they adjoin and the caudal continuation of the anteromedian nucleus. It does not include the rostral anteromedian nucleus or the Edinger—Westphal nucleus caudal to the level where its cells are continuous with those of the anteromedian nucleus. These regions do not appear to relate to pupilloconstrictor function.4. The preganglionic nature of the pupilloconstrictor area within the small celled component was verified by an examination of the distribution of the antidromic evoked potential produced by stimulation of the preganglionic fibres at the ciliary ganglion.5. The distribution of pupilloconstrictor responses obtained from extranuclear structures suggested the presence of an excitatory tract from the region of the posterior commissure to the pupilloconstrictor nucleus.6. There was no indication of a lateral division of function within the pupilloconstrictor nucleus. All the responses obtained from nuclear or supranuclear structures were bilaterally equal.
Effects of ouabain and diphenylhydantoin on transmembrane potentials, intracellular electrolytes and cell pH of rat muscle and liver in vivo
Authors: Williams J. A. , Withrow C. D. , Woodbury D. M. 
Published: December 2014

1. The effects of ouabain and diphenylhydantoin (DPH) to inhibit and stimulate, respectively, the Na+—K+ pump were used to correlate transmembrane resting potentials (RP), ionic gradients, and cell pH (DMO method) in rat muscle and liver in vivo.2. Ouabain effects included a rise in K+ and fall in Na+ concentration in plasma, a rise in intracellular Na+ and Cl− and a fall in K+ concentration and pHi in muscle, and a rise in intracellular K+ concentration in liver.3. Measured muscle RP was decreased from −90 to −65 mV by ouabain with the RP predictable from the Goldman equation for Na+ and K+ with PNa/PK = 0·01.4. Measured hepatic RP was increased from −44 to −48 mV by ouabain, whereas the Goldman equation predicts the potential should decrease. A change in permeability of some ion or activation of an electrogenic pump component is necessary to explain this result.5. DPH produced no significant effect on muscle electrolytes or RP and failed to reverse the effect of ouabain at the time measured and in the doses used.6. DPH produced a slight rise in hepatic cell K+ and a rise from −42 to −47 mV in hepatic RP. This hyperpolarization also cannot be explained without invoking a permeability change or activation of an electrogenic pump.In all cases intracellular Cl− in both muscle and liver changed in the direction expected from the change in the RP. Muscle Cl− appears passively distributed if a constant amount of extra or bound Cl− is first subtracted from each group. Hepatic intracellular Cl− is always less than expected on the basis of passive distribution, although errors in determination do not allow elimination of the possibility that Cl− distribution is determined only by the RP.8. Cell pH and RP data were used to calculate H+ gradients. DPH had no effect on cell pH and only slightly increased the H+ gradient in liver. Ouabain produced a slight fall in muscle cell pH but reduced the H+ gradient by half. In liver only the H+ gradient was increased slightly. The data support the concept of a loose coupling between active H+ and Na+—K+ transport.
Changes in light scattering associated with the action potential in crab nerves
Authors: Cohen L. B. , Keynes R. D. 
Published: December 2014

1. Changes in light scattering from stimulated crab leg nerves were measured in an effort to study changes in structure that occur during the action potential.2. The peak changes in scattering after individual stimuli were 10−4‐10−5 of the resting scattering; signal averaging techniques were used to increase the signal‐to‐noise ratio.3. During the compound action potential there was a transient increase in the 90° scattering which reached a peak about 20 msec after the stimulus. This increase was probably not due to a change in axon volume. Its time course was somewhat slower than that of birefringence changes measured at the same time.4. In normal sea water the transient increase was followed by a longer lasting (persistent) decrease in scattering. This persistent decrease could be converted to an increase by reducing the tonicity of the sea water or by raising the external refractive index. This scattering change may represent a swelling of the axon resulting from the ionic exchanges that occur during the action potential.
Influence of ambient temperature on the thermoregulatory responses to 5‐hydroxytryptamine, noradrenaline and acetylcholine injected into the lateral cerebral ventricles of sheep, goats and rabbits
Authors: Bligh J. , Cottle W. H. , Maskrey M. 
Published: December 2014

1. The influences of ambient temperature (Ta) on the thermoregulatory effector activities and the body temperature (Tb) of intraventricular injections into the sheep, goat and rabbit of 5‐hydroxytryptamine (5‐HT), noradrenaline (NA), acetylcholine (ACh), carbachol and eserine, have been interpreted in terms of a simple neuronal model of the pathways between thermosensors and thermoregulatory effectors.2. In all three species 5‐HT in minimal doses caused a rise in respiratory frequency (RF) and a fall in Tb at high Ta, and a reduction in EMG activity and a fall in Tb at low Ta. These effects could be interpreted as those of an excitatory transmitter acting on the warm receptor—heat loss pathway.3. In all three species NA caused a reduction in RF and a rise in Tb at high Ta, and a reduction in EMG activity and a fall in Tb at low Ta. These effects are interpreted as those of an inhibitory transmitter acting both on the warm sensor—heat loss pathways and on the cold sensor—heat production pathway.4. The effects of ACh and the cholinomimetic substances carbachol and eserine are complex and more difficult to interpret. In small doses the effects on the sheep and goat are those of an excitatory transmitter on the cold sensor—heat production pathway. There was an increase in EMG activity and a rise in Tb at low Ta, and a reduction in RF and a rise in Tb at high Ta. At higher dose levels in the goat and at all dose levels in the rabbit these substances had the reverse effects which are attributed to a synaptic block due to the excess of the excitatory substance.5. The effects of ambient temperature and injected substances upon ear temperature are consistent with the predictions of the model if it is assumed (a) that at high and low ambient temperatures direct thermal effects on ear vessels dominate those of the sympathetic innervation, and (b) that the warm sensor influence is to lower peripheral vasomotor tone, and the cold sensor influence is to increase it.6. The conclusion reached is that when consideration is given to species differences in the thermoneutral ambient temperature and to the possibility that excitatory substances have reversed effects at high dose levels, the effects of 5‐HT, NA and ACh in the control of body temperature are very similar in the sheep, goat and rabbit: 5‐HT is excitatory on the heat loss pathway, ACh is excitatory on the heat production pathway and NA has an inhibitory influence on both pathways.
An examination of the extent of reversibility of thyroxine binding within the thyroxine distribution space in the rabbit
Authors: Nathanielsz P. W. 
Published: December 2014

1. New Zealand white rabbits were injected intraperitoneally with [125]
L‐thyroxine. Experiments were performed after 24 hr had elapsed.2. Thyroxine distribution space was calculated as 129 ml. kg−1. Half‐life of disappearance of thyroxine from the blood of the urethane anaesthetized rabbit was 653 min.3. After exchange of approximately 20 ml. kg−1 whole blood with heparinized blood from a non‐radioactive donor, equilibration of radioactivity in the recipient had produced a peak radioactivity by 2 hr.4. The thyroxine space in which complete exchange took place within 2 hr was 102·7 ± 4·7 ml. kg−1 in six rabbits. This is 79·6% of the thyroxine distribution space.5. These results are compared with observations in the rat.
Studies on the nature of sweat gland ‘fatigue’ in the goat
Authors: Jenkinson D. McEwan , Robertshaw D. 
Published: December 2014

1. The nature of the ‘fatigue’ of sweating that occurs in the goat upon exposure to environmental conditions of 40° C/26° C (dry bulb/wet bulb) has been examined.2. Heat exposure activated all the sweat glands and the decrement in sweating which occurred was due to a decline in the amount of sweat produced by each gland.3. The decline in sweating activity was associated with a decrease in sweat gland volume and a thickening of the glandular wall. The restoration of sweat gland function took approximately 5‐6 hr after removing the animal from the hot environment but the restoration of sweat gland volume took longer.4. The volume of sweat produced was greater than the decrease in sweat gland volume and it is concluded that ‘fatigue’ is due to the rate of expulsion exceeding the rate of sweat production.5. Repeated intravenous injections of adrenaline at 40° C resulted in a decline in sweat output and reduced the normal glandular response to heat exposure.
The separation of renal activity from lung and from the venous effluent from perfused lungs
Authors: Lockett Mary F. 
Published: December 2014

1. Antidiuretic and salt‐retaining activity has been separated from cat and ox lung, and from the venous effluent of blood‐perfused cat lungs, by acetone extraction, gel filtration, partition and thin‐layer chromatography.2. The chromatographic properties of the renally active substance from lung and from pulmonary venous blood are similar.3. The renal actions of these substances, demonstrable in vivo and in the isolated organ, are characterized by reduction in the excretion of water and Na. Renal blood flow, glomerular filtration rate and the urinary Na/K are not significantly affected.4. Concentrations of the lung substance which equate with angiotensin II‐val5‐amide in reduction of urinary Na in rats during water diuresis and under alcohol sedation do not raise the mean arterial pressure of the anaesthetized rat nor contract the superfused rat colon. At these dose levels angiotensin II is markedly vasopressor and contracts the superfused rat colon.
A study of the electrochemistry and osmotic relationships of the cochlear fluids in the neonatal rat at the time of the development of the endocochlear potential
Authors: Bosher S. K. , Warren R. L. 
Published: December 2014

1. Changes in the endocochlear potential between the 8th and 18th days after birth were investigated in the rat. Initially the potential was low but its magnitude increased rapidly between the 11th and 16th day. During the 13th and 14th days the rate of increase was approximately 1 mV/hr.2. The rapid potential increase arose virtually simultaneously in all three turns of the cochlea.3. Histological examination revealed the cochlea, including the hair cells of Corti's organ and the stria vascularis, to be fully mature before the period of rapid change in the endocochlear potential, apart from the cells of Claudius, whose final development coincided with the latter part of this phase.4. The endolymphatic sodium concentration (average 1·0 m‐equiv/l.) had attained the very low adult level in the earliest period studied. The potassium and chloride concentrations were slightly below the normal adult levels, the result of some degree of general hypo‐osmolality present at this time.5. The endolymphatic ionic concentrations remained unchanged during the phase of rapid increase in the endocochlear potential.6. The findings thus indicate that the distinctive endolymphatic ionic composition and the endocochlear potential arise largely independently and in succession during cochlear maturation.7. No differences in osmotic pressure were demonstrated between endolymph, perilymph and serum. The problems concerning the homoeostasis of the inner ear fluids do not consequently seem to be complicated by unusual hydrodynamic aspects.8. Alterations in body fluid osmolality, produced by intraperitoneal injection of water or hypertonic glycerol, were accompanied by simultaneous changes in the osmotic pressures of the inner ear fluids. Some portion of the membranes bounding the endolymphatic space is therefore considered to be freely permeable to water.9. The investigations provide no further information about the nature of the endocochlear potential, although an increase in the electrical resistance of the cochlear duct membranes is thought responsible for its appearance. The time relationships of this period support the concept that the potential is an essential feature of the mechano‐electric transduction process.
Salt‐gland secretion and blood flow in the goose
Authors: Hanwell Ann , Linzell J. L. , Peaker M. 
Published: December 2014

1. Salt‐gland blood flow in the domestic goose has been measured using a combination of Sapirstein's indicator fractionation technique for organ blood flow and Fegler's thermodilution method for cardiac output.2. Nasal salt secretion was induced by giving 0·5
M‐NaCl or 0·154
M‐NaCl
I.V. or by giving artificial sea water by stomach tube into the proventriculus.3. During secretion, salt‐gland blood flow increased from 82·7 ± 21·9 ml./100 g tissue. min to as high as 2179 ml./100 g. min (mean 1209 ± 140).4. The rate of secretion in response to salt loading was very variable and was not correlated with the rate of blood flow.5. From the data obtained, it could be calculated that the median values for the percentage extraction of ions from the arterial plasma were Na 15%, K 35%, Cl 21% and water 5·8%.6. Atropine abolished secretion but not the increase in blood flow produced by salt loading.7. Unilateral complete denervation abolished secretion from and the increase in blood flow through the operated but not the control gland.8. Anaesthesia, induced by pentobarbitone sodium, almost completely blocked secretion and the increase in blood flow in the salt‐gland in response to salt loading.9. In geese given 0·5 or 0·154
M‐NaCl
I.V. a positive, significant correlation was found between the total amount of nasal secretion collected over 30 min and the concentrations of Na and Cl in the nasal fluid. However, when the time course of secretion was followed in any one bird, the rate of secretion was inversely related to the concentrations of Na and Cl.10. Harderian gland blood flow was not affected by salt loading.