bluuebunny/crossref_metadata_2025_split huggingface dataset:
Localization of intra‐abdominal thermoreceptors in the ewe
Authors: Rawson R. O. , Quick K. P. 
Published: December 2014

1. In neutral environmental temperatures, shivering was induced in sheep by intra‐ruminal cooling. Shivering was then depressed for a period by intra‐abdominal heating. Intra‐abdominal heating without ruminal cooling induced panting and a reduction of caval temperatures. Posterior caval temperatures were found to be inappropriate to the responses observed.2. Intra‐abdominal heating of sheep in cold and warm environments depressed shivering and augmented panting respectively. Unilateral splanchnotomy abolished these responses on the ipsilateral side.3. The results are interpreted to indicate that the thermoreceptors stimulated lie within the walls of the rumen and intestine, and possibly the mesenteric veins.4. The splanchnic nerves are indicated as the afferent pathway for these receptors, and differential splanchnic innervation of the gut is suggested to explain unilateral abolition of the response to warming.
Psychophysical estimates of visual pigment densities in red‐green dichromats
Authors: Miller S. S. 
Published: December 2014

1. The spectral sensitivity of red‐green dichromats was determined using heterochromatic flicker photometric matches (25–30 c/s) on the fovea. These matches are upset after a bright bleach and consequently the spectral sensitivity is altered.2. Preliminary experiments indicate that under the conditions in which these experiments were performed, the blue cone mechanism of deuteranopes and protanopes cannot follow 20 c/s flicker. If dichromats lack one of the normal pigments then the upset of these matches monitors the change in spectral sensitivity of a single mechanism.3. After a bleach which removes all the cone pigments, the spectral sensitivity recovers with the time course of pigment kinetics as measured by densitometry.4. An intense background also changes the relative spectral sensitivity of the dichromats. On real equilibrium backgrounds, the changes in spectral sensitivity follow those predicted by the pigment changes measured by densitometry. The predicted changes are obtained by modifying the Rushton equilibrium equation to take into account the density of pigment.5. The relationship of these changes to the luminance of the background is independent of the colour of the background light.6. In contradistinction the effect is dependent on the colour of the lights which were flickered. These experiments indicate that a narrowing of the spectral sensitivity curves takes place on both sides of the dichromats' λmax.7. The change in relative spectral sensitivity as a function of background intensity was also determined by increment threshold measurements. These changes can be expressed in terms of deviations from Weber's law (ΔI/I = const.) if ΔI and I represent the number of chromophores destroyed by the test and background.8. The relative spectral sensitivity of the dichromat was changed by decentering the point of pupil entry. This upset was abolished by bleaching. The size of the upset was correlated with the magnitude of the S—C I effect.9. Given the hypothesis of pigment density (self‐screening), the results of expts. (3)‐(8) are consistent and allow the calculation of a maximum optical density for those pigments which underlie the dichromats' long‐wave mechanism. For the deuteranope a Dλmax of 0·5–0·6 is calculated and for the protanope a Dλmax of 0·4–0·5 is obtained.
Localization of cation interactions in the smooth muscle of the guinea‐pig taenia coli
Authors: Goodford P. J. , Wolowyk M. W. 
Published: December 2014

1. An electron microscopic method has been developed and used to study cation binding sites in smooth muscle.2. Uranyl cations normally bind to the external surface of the plasma membrane. However, uranyl also binds to the inner surface when it is accessible. Similar binding has been observed in skeletal muscle, nerve and red blood cells.3. Uranyl binds electrostatically, and the binding can be competitively reversed by other cations. By a quantitative procedure the relative affinities Ca2+ ≃ Mg2+ ≫ K+ > Na+ for the membrane sites have been determined. This sequence is in agreement with previous values determined analytically.4. The results support a counter‐cation hypothesis for the plasma membrane surfaces of the taenia coli, and may explain features of the electrical activity in smooth muscle.
Disparity processing of spatial frequencies in man
Authors: Felton Thomas B. , Richards Whitman , Smith Robert A. 
Published: December 2014

1. Adaptation to a high‐contrast sine‐wave grating has been shown previously by Blakemore & Campbell (1969) to raise the modulation required to detect a low‐contrast grating that has the same or similar spatial frequency as the adapting grating.2. A similar adaptation effect occurs when the adaptation and test gratings are seen binocularly and are presented off the plane of fixation. When the gratings are not located on the plane of fixation, however, the greatest rise in threshold following adaptation occurs for test gratings presented in the same plane as the adapting grating. Thus, the neural mechanisms adapted to the high contrast patterns must be processing disparity information.3. The spatial frequency response of the disparity adaptation effect has been measured by adapting to gratings of different spatial frequencies presented at a given disparity, and comparing threshold elevations for identical test gratings presented in the same (disparate) plane as the adapting grating or in the plane of fixation.4. The unbiased adaptation effect specific to disparity is greatest for gratings whose periods are twice the disparity.5. There is no adaptation effect specific to disparity for individuals possessing only convergent or only divergent disparity mechanisms.6. The results suggest that disparity mechanisms make bar by bar correlations as opposed to edge by edge correlations and that narrow bar detectors feed small disparity mechanisms whereas wide bar detectors feed large disparity mechanisms.
Spinal pathways projecting to the cerebral first somatosensory area in the monkey
Authors: Andersson Sven A. , Norrsell Kerstin , Norrsell Ulf 
Published: December 2014

1. Potentials evoked with short latency in the cerebral post‐central gyrus after intradermal electrical, or adequate light tactile stimulation of the contralateral body half have been studied in the monkey, before and after transection of different spinal pathways at the upper cervical level.2. Initially, positive potentials evoked by both types of stimulus were recorded after transection of the dorsal funiculi with the same somatotopic, topographical distribution as before the lesion.3. The potentials recorded after transection of the dorsal funiculi could be evoked via one pathway located in the dorsal half of the lateral funiculus ipsilateral to the afferent input, and another pathway located, at least partially, in the ventral funiculus contralateral to the afferent input.4. Of these two pathways, the crossed ventral pathway was found necessary to keep the topographical distribution of the evoked potentials unaltered.
Effect of prolonged ouabain treatment on Na, K, Cl and Ca concentration and fluxes in cultured human cells
Authors: Lamb J. F. , McCall D. 
Published: December 2014

1. Girardi and Hela cells (derived from human heart and cervix respectively) were grown as monolayer cultures in B.M.E. (Eagles basal medium) containing concentrations of ouabain up to 5 × 10−8
M for periods ranging up to 5 days. The cell sizes, numbers, Na, K, Cl, and Ca concentrations and fluxes were then measured.2. Twenty‐four hours incubation in ouabain concentrations equal to or less than 5 × 10−8
M caused a rise in [Na]i and an almost equal fall in [K]i to new steady levels. The concentrations so reached were linearly related to the ouabain concentrations, such that in 5 × 10−8
M ouabain [Na]i rose to 124 m‐mole/l. intracellular water and [K]i fell to 55 m‐mole/l. i.c. water in Girardi cells. In Hela cells the changes were smaller at any particular ouabain concentration. These levels were maintained constant for at least 5 days.3. In cells in the logarithmic phase of growth, raising [Na]i and lowering [K]i by ouabain caused a slowing of growth rate proportional to the ouabain concentration used. In cells in the stationary phase there was no change in the cell numbers over 24 hr. The volume of the cells was not directly affected by the treatment.4. Reducing [K]o from the normal value of 5·4 to 2·5 m
M increased the effect of any ouabain concentration, whereas increasing [K]o to 7·5 decreased the effect of ouabain.5. Reduction of [K]o to 2·5 m
M had no effect on the [K]i or [Na]i but halved the cell numbers, probably by a reduction in the growth rate. The mechanism of this effect is obscure.6. In Girardi cells raising [Na]i and lowering [K]i by prolonged treatment increases the total Na fluxes and decreases the total K fluxes but keeps the total Na + K flux constant. High‐Na, low‐K cells had a reduced Na:K exchange compared to fresh cells and also had a Na:K pumped ratio nearer 4:1 than the 3:2 normally found.7. These cells also show ouabain‐sensitive and ouabain‐insensitive Na:Na exchanges. In high‐Na, low‐K cells the ouabain sensitive Na:Na exchange is the same as in fresh cells. The effect of treatment on the ouabain insensitive Na:Na exchanges has not been elucidated.8. The Cl content and fluxes are not altered by prolonged ouabain treatment. From this it is inferred that the membrane potential in high‐Na, low‐K cells is the same as in normal cells.9. High‐Na, low‐K cells have the same calcium content and fluxes as fresh cells. From this it is concluded that there is no Na:Ca coupling in these cells.
A sympathetic reflex elicited by distension of the mesenteric venous bed
Authors: Andrews C. J. H. , Andrews W. H. H. , Orbach J. 
Published: December 2014

1. The proximal ends of the distal portions of severed nerves coming from the small intestine were monitored for nerve impulses. When the mesenteric venous pressure was increased by mechanical obstruction of the portal vein there was a proportional increase in the frequency of afferent action potentials, the frequency falling immediately the venous pressure was reduced. The stimulus for the increased rate of nerve discharge appeared to be pressure within the mesenteric venous bed and not anoxia, for obstruction of the arterial supply to the gastrointestinal tract did not activate the same fibres.2. Obstruction of the portal vein led to an increased efferent nervous discharge to the intestines. The reflex increase persisted after bilateral vagotomy, after transection of the spinal cord at the level of C7 and after section of the hepatic nerves, but was abolished by section of the intestinal nerves.3. It is suggested that the spinal reflex is concerned with local distribution of blood and that the mesenteric venous ‘volume’ or ‘stretch’ receptors which initiate the reflex are similar to those described elsewhere in the body.
Adaptation to square‐wave gratings: inhibition between spatial frequency channels in the human visual system
Authors: Tolhurst D. J. 
Published: December 2014

1. The observation that the detection threshold for a square‐wave grating depends only on that of its fundamental was confirmed by showing that adapting to the fundamental spatial frequency caused elevation of the square‐wave threshold, to the same extent as the fundamental threshold was elevated by the same adapting pattern. Adapting to the third harmonic frequency had no effect on the square‐wave threshold.2. Adapting to a square‐wave grating should elevate the thresholds for both the fundamental and third harmonic frequencies (Blakemore & Campbell, 1969), and the amount of elevation at each frequency should be predictable from the contrast of that frequency within the square‐wave.3. It was found, however, that both the fundamental and third harmonic, when present in the square‐wave, were much less effective as suprathreshold adapting stimuli than would be predicted from their effects when viewed in isolation.4. Adapting to a mixture of two sinusoidal gratings (with 3:1 frequency ratio) demonstrated that the fall in adapting power was not due to the higher harmonics of the square‐wave nor to nonlinearities in the stimulus display. Similar effects were found when the phase relations of the adapting gratings were changed, showing that the interaction is not a special property of square‐waves or of edges.5. It is suggested that the spatial frequency channels subserving the fundamental and third harmonic frequencies inhibit each other when the patterns are some way suprathreshold. At or near threshold, there is no such reciprocal inhibition.
Synaptic actions of peripheral nerve impulses upon Deiters neurones via the mossy fibre afferents
Authors: Allen G. I. , Sabah N. H. , Toyama K. 
Published: December 2014

1. The cerebellar integration of sensory inputs to Deiters neurones was investigated in decerebrate cats. In some preparations decerebration was combined with transection of the olivocerebellar fibres.2. In the latter preparations peripheral nerve impulses generally produced a response consisting of a sequence of the following post‐synaptic potentials: (i) an initial e.p.s.p. (d1), (ii) early i.p.s.p. (h1), (iii) later i.p.s.p. (h2).3. The mean latencies of d1, h1 and h2 were 5·7, 7·3 and 9·8 msec from the forelimb nerves, and 7·5, 9·0 and 13·4 msec from the hind limb nerves, respectively.4. The stimulus intensity—response relation indicates that the Group I muscle afferents as well as the low threshold cutaneous afferents contribute to the response.5. In the preparations with the intact inferior olive there were additional components of the post‐synaptic potentials: a later e.p.s.p. (d2) and another later i.p.s.p. (h3), their mean latencies being 15·3 and 19·7 msec from the forelimb nerves, and 18·0 and 21·3 msec from the hind limb nerves, respectively.6. The d1 and h2 components were attributed to the mossy fibre afferents and d2 and h3 to the climbing fibres; d1 and d2 were due to excitation through the collaterals of the mossy and climbing fibres, and h2 and h3 to inhibition from Purkyně cells activated by the mossy and climbing fibres, respectively. h1 was too early to be produced through the cerebellum, and was probably mediated by inhibitory neurones in the reticular formation.
Calcium‐dependent amylase release and electrophysiological measurements in cells of the pancreas
Authors: Kanno T. 
Published: December 2014

1. Transmembrane potential, effective membrane resistance, and amylase output were recorded from acinar cells of rat pancreas perfused in vitro.2. Both pancreozymin and acetylcholine hyperpolarized the acinar cells, increased effective membrane resistance, and augmented amylase output.3. The omission of calcium from the perfusion medium increased effective membrane resistance and potential, and abolished the increase in amylase output in response to the drugs.4. A quantitative relation was found between the amount of amylase released by pancreozymin and the concentration of calcium in the perfusion medium at values below the normal 2·5 mM calcium. Excess magnesium did not inhibit the increase in amylase output in response to the drug.5. It is concluded that the release of amylase from the pancreas depends on the entry of calcium into the acinar cells. The entry of calcium seems to be mediated by a carrier in the membrane and may be considered as a ‘facilitated diffusion’.6. The electrophysiological findings taken together with morphological evidence provided by scanning electron microscopy favour the view that pancreatic zymogens are released from the granules in the acinar cells to the lumen by the process known as exocytosis.
Facilitation and inhibition of cell groups within the superior cervical ganglion of the rabbit
Authors: Brimble M. J. , Wallis D. I. , Woodward B. 
Published: December 2014

1. The patterns of facilitation and inhibition of the Sa and Sb components of the post‐ganglionic compound action potential after a single conditioning stimulus were different and dependent on stimulus parameters.2. With submaximal conditioning and test stimuli, the Sa component showed a phase of early facilitation (40–75 msec after the conditioning stimulus) followed by a prolonged tail of facilitation. With maximal stimuli, early facilitation and late facilitation (700–2000 msec after the conditioning stimulus) were separated by a phase of inhibition or relative inhibition, most pronounced 100–300 msec after the conditioning stimulus.3. During early facilitation, a submaximal Sa response was facilitated by 33·1 ± 3·9%, while a maximal Sa response was facilitated by 14·5 ± 2·9%.4. Providing preganglionic C fibres were excited, facilitation of the Sb component remained relatively constant for 40–500 msec after the conditioning stimulus, with no phase of inhibition.5. Early facilitation of submaximal Sa responses was greatest when the conditioning stimulus excited about 50% of the preganglionic B fibres, but that of maximal responses was greatest when the conditioning stimulus excited all the B fibres. The preganglionic C fibres modulated facilitation of the Sa component. Maximal facilitation of this component was associated with depression of the Sb component.6. Submaximal Sa responses are more strongly inhibited than maximal Sa responses 200 msec after a conditioning stimulus. The C fibre pathway seems able to modulate the degree of inhibition of the Sa ganglion cells.7. A neuronal model with divergent and convergent preganglionic B and C fibres supplying Sa ganglion cells is consistent with the results. The preganglionic input is able to vary the size of the subliminal fringe. The Sb component is in part due to the Sa ganglion cells firing to their C fibre input.
Internodal conduction in undissected demyelinated nerve fibres
Authors: Rasminsky M. , Sears T. A. 
Published: December 2014

1. A new method is described for recording external longitudinal currents from single undissected nerve fibres in rat ventral roots. The method permits identification of the sites of fifteen or more successive nodes of Ranvier in a given single fibre and the measurement of internodal conduction times between them.2. Average internodal conduction time for normal ventral root fibres of internodal length between 0·75 and 1·45 mm is 19·7 ± 4·6 (
S.D.) μsec at 37° C. Internodal conduction time appeared to show a minimum for fibres of internodal length 1·0 mm.3. Ventral roots were demyelinated by focal application of diphtheria toxin. Although conduction is markedly slowed in demyelinated fibres, sites of inward membrane current remain spatially separated indicating that conduction remains saltatory to the point of conduction block rather than becoming continuous as in unmyelinated fibres.4. Slowing of conduction appears to be due to changes in the passive electrical properties of the internodal myelin. Evidence is presented suggesting that there is an increase in internodal capacitance and a decrease in internodal transverse resistance at internodes of demyelinated fibres; such changes would have the effect of delaying excitation at the nodes. The changes in passive electrical properties, which appear to be primarily in the vicinity of the nodes, would be consistent with the pathological changes observed in demyelinated fibres.5. Internodal conduction times in demyelinated fibres have ranged from normal (26 μsec at 30° C) to more than 600 μsec. There is a great variation in internodal conduction time at successive internodes of a given single fibre; this presumably reflects the varying severity of demyelination of successive internodes.6. As in normal fibres, nodes of demyelinated fibres generate less current when excited by the second of two closely spaced impulses. This results in an increased internodal conduction time for the second impulse and, at a critically short interstimulus interval, conduction block of the second impulse.7. The increased refractory period of transmission of internodes with increased internodal conduction times is a consequence of the decreased ability of such internodes to sustain propagation in the face of small decreases in nodal current.8. During tetanic stimulation, increases in internodal conduction time are associated with corresponding decreases in nodal current generated by the node proximal to the internode in question.9. It is suggested that changes in the magnitude of the nodal current during repetitive activity are due to changes in transmembrane concentration gradients of sodium, the increased internodal conduction time and eventual conduction block during tetanic stimulation being caused by intracellular sodium accumulation.10. Intracellular sodium accumulation is also offered as the explanation for the post‐tetanic depression seen in demyelinated fibres.
Hypomagnesaemia following theophylline or furosemide injection in ewes: renal versus extrarenal effect
Authors: Larvor P. , Rayssiguier Y. 
Published: December 2014

1. Intravenous theophylline infusion (30 mg/kg body weight during 90 min) induces in normal ewes a magnesuria associated with hypomagnesaemia.Intravenous furosemide infusion (1 mg/kg body weight during 90 min) induces in the same animals a similar magnesuria with only a slight hypomagnesaemia.2. In magnesium deficient ewes, theophylline induces a hypomagnesaemia, without a significant rise in magnesuria.3. Theophylline infusion, with simultaneous reinjection of the excess magnesium excreted in urine, induces a significant hypomagnesaemia.4. Thyroidectomy does not inhibit the effect of theophylline on magnesaemia.5. It is concluded that the effect of theophylline on magnesaemia is mainly of extrarenal origin, while the effect of furosemide is only renal. The effect of theophylline is not mediated through calcitonin secretion.
Intrahepatic distribution of portal and hepatic arterial blood flows in anaesthetized cats and dogs and the effects of portal occlusion, raised venous pressure and histamine
Authors: Greenway C. V. , Oshiro G. 
Published: December 2014

1. Radioactive microspheres were used to determine the distribution of arterial and portal flows within the liver. 141Ce‐microspheres and 51Cr‐spheres were given to allow two determinations of flow distribution in each animal and experiments are described to establish the accuracy and validity of the method.2. Mean flow/g to any lobe or segment of a lobe in a group of animals was not markedly different from the mean flow/g to the whole liver, and in general the liver was homogeneously perfused with both portal and arterial blood. However, in any one liver, some areas received a relatively greater flow (up to 300%) and some a relatively smaller flow (down to 50%) at the time the microspheres were given. The gall bladder received a much smaller portal flow/g than the parenchyma but its arterial flow/g varied widely in different animals.3. If portal flow to an area of parenchyma was reduced by occlusion of a branch of the portal vein, this area received a significantly increased arterial flow.4. An increase in hepatic venous pressure did not cause a significant change in the intrahepatic distribution of either arterial or portal flows in cats.5. In dogs, infusions of histamine into the portal vein caused a redistribution of portal flow away from the free ends of the lobes towards the hilar ends but the distribution between lobes did not change and there was no redistribution of arterial flow.