bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrical profiles in the corneal epithelium
Authors: Klyce S. D. 
Published: December 2014

1. The potentials and resistances associated with the cell membranes of the rabbit corneal epithelium were studied with 3 M‐KCl‐filled micro‐electrodes.2. In the isolated cornea, the transepithelial potential was identical in polarity and magnitude to the simultaneously measured total corneal potential. In contrast to previous findings, the stromal potential was positive to the tear side. Negative stromal potentials apparently derive from inadequate electrodes or method of penetration, and were not found to be a function of filling solution. Transepithelial potential was also identical to over‐all corneal potential in the living rabbit eye.3. In the isolated preparation, the average potential profile occurred in three distinct steps across the epithelium. By means of iontophoretic dye injection it was shown that these steps occurred across the outer membrane of the squamous cell, the transition region between the wing and basal cell, and across the inner membrane of the basal cell.4. The transverse membrane resistance of the outer epithelial membrane accounted for 60% of total corneal resistance. As a result, short‐circuit current, which depolarizes the cornea, led to a hyperpolarization of the outer membrane, while affecting deeper membrane potentials little or not at all.5. The spontaneous potential of the outer membrane varied inversely with corneal potential in both normal and chloride‐free Ringer, while the potential of the inner membrane of the basal cell was relatively constant, approaching the theoretical Nernst potential for potassium. The potential of the outer membrane was at chloride equilibrium and was sensitive to extracellular shunts. A Thevenin equivalent drawn for the epithelium suggested that half of the outer membrane potential could be attributed to loop currents. The potential step between wing and basal cells could be accounted for in terms of loop currents driven by the corneal potential through the epithelium.6. The potential profile of the frog corneal epithelium was similar to that of the rabbit. However, the major resistance in the frog cornea was associated with the basal cell membrane rather than with the squamous cell outer membrane. Quasi‐instantaneous rectification was found for both epithelia. In the rabbit chloride rectified inwardly.
Neurotrophic regulation of muscle cholinesterase: effects of botulinum toxin and denervation
Authors: Drachman Daniel B. 
Published: December 2014

1. In order to determine the role of acetylcholine (ACh) transmission in neurotrophic regulation of muscle cholinesterase (ChE), the effects of botulinum toxin treatment were compared with those of denervation, in terms of two fractions of muscle ChE. The sternocleidomastoid muscles of rats were either denervated or injected with botulinum toxin. After 7 days the muscles were frozen, and sequential sections were assayed for acetylcholinesterase activity. By this method, the ChE activity of end‐plates (EPChE) and non‐end‐plate regions (background ChE, BChE) were separately determined.2. The background ChE was reduced to the same extent by botulinum toxin and denervation. This is interpreted to mean that the neurotrophic regulation of BChE may be wholly cholinergic.3. The EPChE was significantly reduced by both treatments, but the effect of botulinum toxin was only half as great as that of denervation. This indicates that EPChE is only partially regulated by ACh transmission. The larger effect of denervation suggests that some non‐cholinergic influence may be operating in this situation as well. Disruption of the structural integrity of the end‐plate, with consequent loss of binding sites for the ChE, may account for the additional effect of denervation.
The effects of decerebration on the reflex response to pulmonary vein distension
Authors: Albrook Sally M. , Bennion Glenda R. , Ledsome J. R. 
Published: December 2014

1. A method is described for the decerebration of dogs using high frequency coagulation. Animals made decerebrate by this method showed a slowing of the heart rate and a decrease in arterial pressure.2. Distension of the pulmonary vein—left atrial junctions by the inflation of small balloons caused an increase in heart rate in intact and decerebrate dogs. The magnitude of the response was not significantly different in the two states.3. The increase in heart rate caused by pulmonary vein distension was shown to be a reflex. It was significantly reduced by injection of propranolol both before and after decerebration. Cervical vagotomy always prevented any response.4. The similarity of the responses before and after decerebration suggests that structures rostral to the superior colliculus are not required for the appearance of the full reflex effect.5. The magnitude of the response remaining after administration of propranolol raised the question of the efficacy of propranolol as a β‐blocking agent in this experimental situation, or alternatively suggests the possibility of the existence of an efferent vagal component to the reflex response.
Kinetic properties of the sodium current in striated muscle fibres on the basis of the Hodgkin—Huxley theory
Authors: Ildefonse Michèle , Roy Guy 
Published: December 2014

1. The kinetic properties of the sodium current in skeletal muscle fibre, obtained from records in a double sucrose‐gap apparatus, have been analysed in terms of the Hodgkin—Huxley formulation by means of a curve fitting computer program.2. The net sodium currents were obtained by subtracting records in Ringer and Ringer tetrodotoxin; the currents are inward for depolarizations V from +25 to +128 mV (VNa). The INa—V characteristic shows a small inward rectification for V > + 128 mV.3. The characteristics of both sodium conductance and permeability are described.4. The activation and inactivation parameters, m and h, are calculated and compared with those experimentally established in a previous work (Ildefonse & Rougier, 1972) and with the results of Adrian, Chandler & Hodgkin (1970).5. The currents calculated with these parameter values fit rather well with the experimental ones, the permeability approach being slightly better.6. The main difference between the experimental and calculated curves is the slower inactivation of the calculated current at V = +55 mV; this difference is envisaged as a possible consequence of some activity in the tubular system of the muscle fibre.
Comparison of the effects of hepatic nerve stimulation on arterial flow, distribution of arterial and portal flows and blood content in the livers of anaesthetized cats and dogs
Authors: Greenway C. V. , Oshiro G. 
Published: December 2014

1. The responses to hepatic nerve stimulation were studied in cats and dogs anaesthetized with sodium pentobarbitone. In three series of experiments, hepatic arterial flow was recorded by an electromagnetic flowmeter, intrahepatic distributions of arterial and portal flows were studied by radioactive microspheres, and hepatic volume responses were measured by a plethysmographic method.2. In cats, nerve stimulation produced a temperature‐dependent decrease in hepatic arterial flow which was not maintained and autoregulatory escape occurred. In dogs, the initial decrease in arterial flow was similar but escape did not occur and the vasoconstriction was well maintained.3. In both cats and dogs, stimulation of the hepatic nerves did not cause a redistribution of either arterial or portal flows within the liver. Autoregulatory escape in the liver of the cat was not associated with an intrahepatic redistribution of arterial flow and is best interpreted as relaxation of the same vessels which were initially constricted, due to increased production of a vasodilator factor.4. Stimulation of the hepatic nerves caused a marked temperature‐dependent decrease in hepatic volume which was well maintained and the responses were similar in cats and dogs. The quantitative importance of the liver as a blood reservoir is compared in relation to other vascular beds and the concept of the blood volume reserve is discussed.
Light‐induced changes in the electrical impedance of the isolated frog retina
Authors: Coles J. A. 
Published: December 2014

1. An isolated frog retina was mounted in an impedance chamber and superfused on its vitread surface.2. Changes in the real part of the impedance (ΔR) and also in the imaginary part were measured using alternating current in the frequency range 1–300 kHz passed from one surface of the retina to the other.3. Under most conditions, the response to a flash of light, measured at frequencies below about 100 kHz, was a decrease in the real part of the impedance (ΔR < 0).4. The geometry of the electrodes was such that the system was particularly sensitive to changes in the impedance of the layer of photo‐receptor outer segments. It was confirmed that most of ΔR did arise here and that it was mediated by the absorption of light in rod photo‐pigment.5. The magnitude of ΔR increased when the channels between the outer segments were constricted, e.g. by osmotic swelling of the outer segments. In addition to this increase, a further increase was seen following the commencement of recording in most of the experiments from which usable measurements were obtained.6. In such retinas, the magnitude of ΔR was greatest when measured at a frequency in the range 3–32 kHz, the largest changes being of the order of 0·1% of the resting value. A light flash bleaching about 1% of the pigment was sufficient to produce this. The onset of ΔR was apparent within 1 msec of the flash (at 15° C); it reached a maximum in 0·5‐4 sec and then returned towards the base line.7. The main component of ΔR was attributed to a decrease in the resistance of the spaces between the outer segments. In addition, there was a resistance increase which occurred at some other site, probably the surface membrane. The first of these components had an onset slightly more rapid than the second, and both occurred irrespective of whether the major cation in the superfusate was sodium or potassium.
Functional relationship of longitudinal and circular layers of the muscularis externa of the rabbit large intestine
Authors: McKirdy H. C. 
Published: December 2014

1. The functional relationship of the longitudinal and circular layers of the muscularis externa of the rabbit large intestine has been studied in a flat preparation.2. Evidence is presented that mechanical activity can be recorded independently and simultaneously from the two muscle layers of the flat preparation. Such evidence accrues mainly from results obtained from the flat preparation in response to various drugs.3. During spontaneous rhythmic contractions and during the response to pelvic (parasympathetic) nerve stimulation, both layers show similar activity, never opposite or reciprocal activity.4. In this flat preparation, the mechanism controlling the level of sustained tension (i.e. ‘tone’) may be dissociable, within limit, from the mechanism controlling rhythmic contractions.
Effects of chemicals on receptors and horizontal cells in the retina
Authors: Murakami Motohiko , Ohtsu Kohzoh , Ohtsuka Teruya 
Published: December 2014

1. By applying atomized chemical solutions on to gecko and carp retinae, neuropharmacological reactions of the photoreceptors and horizontal cells were observed.2. Sodium
L‐glutamate and
L‐aspartate, glycine, ACh and GABA, had no appreciable effect on the photoreceptor activity.3. Carp horizontal cells were depolarized by both
L‐glutamate and
L‐aspartate. When maximally depolarized, the action of the endogenous transmitter from the receptor terminals was completely masked, resulting in abolition of the S‐potentials.4. Responses to red light in both L‐ and C‐type horizontal cells were more strongly affected by aspartate than responses to blue light.5. Glycine and GABA hyperpolarized the horizontal cells, and the S‐potentials were diminished.6. ACh had no effect on the activity of the horizontal cells.
Frequency‐dependent differences in the responses of the capsular and vascular smooth muscle of the spleen of the dog to sympathetic nerve stimulation
Authors: Davies B. N. , Gamble J. , Withrington P. G. 
Published: December 2014

1. The responses of the capsular and vascular smooth muscle to splenic nerve stimulation have been studied simultaneously in the isolated blood‐perfused dog's spleen.2. Low frequencies of splenic nerve stimulation (below 1·0 Hz) caused pronounced contraction of the splenic capsule but little or no constriction of the splenic vascular bed.3. Splenic contraction reached a maximum at stimulation frequencies of 1–2 Hz; maximum vasoconstriction occurred at frequencies of 7–10 Hz.4. The separation of responses of the capsular and vascular smooth muscle was mimicked by close arterial infusions of either adrenaline or noradrenaline.5. The maximum responses of the splenic vascular smooth muscle to nerve stimulation, adrenaline and noradrenaline were not significantly different.6. The maximum reduction in spleen volume to sympathetic nerve stimulation was significantly greater than the maximum response to close arterial noradrenaline.7. The maximum contractions of the spleen to adrenaline and noradrenaline were not significantly different. At concentrations producing submaximal responses adrenaline was more potent than noradrenaline.8. It is suggested that the frequency dependent separation of smooth muscle responses to sympathetic nerve stimulation is due to a different sensitivity of the capsular and vascular smooth muscle to the chemical transmitter noradrenaline.9. The results are discussed in the context of the function of the dog's spleen.
Blood volume determination in the mouse
Authors: Riches A. C. , Sharp J. G. , Thomas D. Brynmor , Smith S. Vaughan 
Published: December 2014

1. The blood volume of the mouse has been measured using 59Fe‐labelled red cells to determine the red cell volume and 131I‐labelled human serum albumin to determine the plasma volume.2. Values for the blood volume of 95·0 ± 1·5, 96·3 ± 2·7 and 84·7 ± 1·2 ml./kg body wt. were found for CSI female, CBA female and CBA male mice respectively.3. A marked discrepancy was observed between the venous (cardiac) haematocrit and the whole body haematocrit.4. The blood volume of the mouse must be determined from the red cell volume and the plasma volume, measured using appropriate labels, and not from the red cell volume or the plasma volume using the venous haematocrit.
Gastric emptying and secretion in the milk‐fed calf
Authors: Bell F. R. , Razig S. A. D. 
Published: December 2014

1. For a few weeks, immediately post‐natally, the abomasum of the ruminant stomach can be regarded as the analogue of the simple stomach for at this time food passes directly to the abomasum because of closure of the oesophageal groove.2. Using standard fractional and serial test meal techniques discussed by Hunt (1956) and adapted for use in the calf, abomasal emptying, acid and pepsin secretion have been examined. Phenol red was used as a marker to measure volume changes of the test meal.3. Abomasal emptying is exponential in character whether large or small volumes of fluid are instilled into the abomasum. The initial and end phase of emptying shows variable rates between animals.4. Glucose and lactose solutions inhibit abomasal emptying as well as acid production.5. Sodium chloride and sodium bicarbonate of low concentration, near isotonic with blood plasma, stimulate abomasal emptying but the bicarbonate is most effective. Hypertonic solutions of these salts inhibit abomasal emptying.6. Pepsin secretion in the abomasum of the calf is not affected by test meals of glucose, lactose, sodium chloride or sodium bicarbonate.7. These results shows a great similarity between the physiology of the abomasum of the milk‐fed calf and the simple stomach. This suggests that the same duodenal receptors, discussed by Hunt & Knox (1968), which control gastric movement in man are also effective in controlling gastric emptying in the milk‐fed calf.
The effect of a preceding stimulus on temporal facilitation at corticomotoneuronal synapses
Authors: Muir R. B. , Porter R. 
Published: December 2014

1. Intracellular recordings were made of minimal corticomotoneuronal e.p.s.p.s in lumbar motoneurones of anaesthetized monkeys. For intervals of 2 msec and greater between paired cortical shocks, the average time course of facilitation of the second e.p.s.p. with respect to the first could be fitted closely by a negative exponential with a time constant of 10 msec.2. In the same motoneurones, ‘triplets’ of corticomotoneuronal e.p.s.p.s were generated by delivering three identical stimuli to the motor cortex. Considering the triplet as a conditioning e.p.s.p. followed by a test pair, the facilitation of the third e.p.s.p. with respect to the second was measured for various combinations of test and conditioning intervals. In each case the amplitude of the third e.p.s.p. was also compared with that of the first (conditioning) e.p.s.p.3. The effect of a brief conditioning interval was to reduce considerably the facilitation of the third e.p.s.p. with respect to the second at all test intervals from 2 to 50 msec. Combinations of brief conditioning intervals (e.g. 2 or 5 msec) and long test intervals (e.g. 20 or 50 msec) caused the third e.p.s.p. to be smaller than the second. As the conditioning interval lengthened, facilitation in the test pair increased towards the unconditioned values at all test intervals.4. Facilitation of the third e.p.s.p. with respect to the first could be described approximately as the linear addition of two facilitation components, one due to the conditioning input and one due to the first stimulus of the test pair. Each component followed the same negative exponential time course as found for an isolated pair of e.p.s.p.s and each of the first two inputs contributed to the facilitation of the third e.p.s.p. as if the other of these two inputs had not occurred.
The action of calcium at spinal neurones of the frog
Authors: Dambach G. E. , Erulkar S. D. 
Published: December 2014

1. The action of Ca on membrane excitability and synaptic transmission at motoneurones of the isolated spinal cord of the frog has been studied.2. Impulse propagation along presynaptic fibres was unaffected by [Ca] in the range of 0–10 m
M in the presence of 1 m
M‐Mg.3. Motoneurone membrane excitability was within normal ranges when the cord was bathed in low or 0 Ca solutions containing 1 m
M‐Mg but was depressed in 5 or 10 m
M‐Ca solutions.4. Spontaneous miniature synaptic potentials were recorded in the presence of tetrodotoxin. The frequencies were reduced but not abolished in the absence of bath Ca, but were increased greater than twofold in 5 or 10 m
M‐Ca in comparison to those in normal Ringer solution (1 m
M‐Ca).5. Iontophoretic application of Ca both near to and remotely from the intracellular recording site (presumably in the soma) caused facilitation of elicited post‐synaptic potentials.6. It is concluded that the action of Ca at these central synapses is identical to that described at the neuromuscular junction.
An electrophysiological investigation of the receptor apparatus of the duck's bill
Authors: Gregory J. E. 
Published: December 2014

1. The properties of receptors in the duck's bill have been studied by recording from units isolated by dissecting fine filaments from the maxillary and ophthalmic nerves.2. The units studied were divisible into three groups, phasic mechanoreceptors responsive to vibration, thermoreceptive units, and high threshold mechanoreceptors.3. Vibration‐sensitive mechanoreceptors (113 units) had small receptive fields, showed a rapidly adapting discharge to mechanical stimulation of the bill, were sensitive to vibratory but not to thermal stimuli and showed no background discharge.4. Temperature receptors (twenty‐one units) were insensitive to mechanical stimulation and showed a temperature‐dependent background discharge. Sudden cooling produced a transient increase in discharge frequency.5. High threshold mechanosensitive units (eight units) gave a slowly adapting discharge to strong mechanical stimulation and were insensitive to vibratory and thermal stimulation.6. It is concluded that the low‐threshold, vibration‐sensitive responses come from Herbst corpuscles. No specific function can yet be assigned to the Grandry corpuscles.
Isolation of components of admittance change in rod outer segments
Authors: Falk G. , Fatt P. 
Published: December 2014

1. Rods were separated by equilibration on a bovine serum albumin (BSA) density gradient into two major fractions, differing in their response to light.2. In one fraction the response, measured as a change in the real part of admittance ΔG, appeared to consist exclusively of component I, while in the other, component II was prominent.3. Evidence is presented that component I arose in damaged rods. This follows from observations on rods which have been deliberately damaged by freezing followed by thawing, or by fragmentation.4. In such damaged rods, component II was absent while component I was increased in amplitude.5. The frequency dependence of component I in isolation was characterized as a positive ΔG of constant amplitude from low frequencies up to the characteristic frequency fY for the major dispersion of admittance. Above this frequency, it declined to a variable extent.6. The frequency dependence of component II observed in isolation was consistent with the previous analysis.7. A negative‐going ΔG is described which was linear with the amount of rhodopsin bleached and which was frequency independent up to the highest frequency of measurement (17 MHz).8. The origins of component I and the negative component are discussed.
Muscle spindle afferent studies in the baboon
Authors: Koeze T. H. 
Published: December 2014

1. The muscle spindle afferent conduction velocity and response to muscle twitch and stretch in young baboons has been recorded in order to find a conduction velocity that can be used to separate primary and secondary afferents.2. A number of the features of the response of the spindle afferents to stretch were examined. It was found that none could distinguish between primary and secondary afferents with greater certainty than the conduction velocity.3. Spindle afferents with conduction velocities below 50 m/sec can be classified as secondary and those with conduction velocities above 68 m/sec can be classified as primary with a reasonable degree of certainty.4. The spindle afferents with conduction velocities between 51 and 67 m/sec are most likely not a separate intermediate group but represent a region of overlap between the two groups.5. Comparisons of the difference between the response of primary and secondary afferents to overstretch suggested a mechanism to explain the saturation of the primary afferent response at frequencies far below those at which it is capable of firing.