bluuebunny/crossref_metadata_2025_split huggingface dataset:
Work‐induced hypertrophy in exercised normal muscles of different ages and the reversibility of hypertrophy after cessation of exercise
Authors: Goldspink G. , Howells K. F. 
Published: December 2014

1. Groups of male hamsters of different ages were subjected to a weight‐lifting exercise regimen, and the biceps brachii, soleus and extensor digitorum longus (EDL) muscles examined for structural changes occurring in response to the increased workload. In addition, two groups of adult hamsters were left to recover from the exercise stimulus for 5 and 15 weeks respectively.2. All the exercised muscles exhibited muscle fibre hypertrophy, and the extent of the hypertrophy was greater in the younger animals. In all age groups, the biceps brachii and EDL showed more hypertrophy than did the soleus. There was no significant increase in fibre number after exercise.3. In both groups allowed to recover from the exercise stimulus, the fibre dimensions reverted back to those of the control muscles; this appeared to be complete after 15 weeks recovery.4. Electron microscopical studies of fibres from exercised and control biceps brachii revealed no significant changes with exercise in the proportions present of myofibrillar, mitochondrial and tubular components within muscle fibres of the same size.
Vacuolar transcellular channels as a drainage pathway for cerebrospinal fluid
Authors: Tripathi Brenda J. , Tripathi R. C. 
Published: December 2014

1. Based on our ultrastructural investigations in monkeys, we report here a new concept as to the physiological mechanism of drainage of cerebrospinal fluid (c.s.f.) which would seem to bridge the gap between the two apparently opposing views of ‘closed’ and ‘open’ system.2. Our studies reveal the presence of an intact mesothelial lining of the arachnoid mater, including its villus‐like projections and herniations into the dural sinus and its lacunae, adjacent cells being joined by tight junctions; in addition we have observed for the first time that many lining cells in the region of the superior sagittal sinus are characterized by unit membrane‐bound, electron‐optically empty giant vacuoles of several micrometres diameter. In one monkey with a fresh subarachnoid haemorrhage, many vacuoles were filled with plasma proteins and some contained intact blood corpuscles.3. Serial section analysis showed that the vacuoles were in fact invaginations from the basal aspect of the cell surface and were evidently in direct communication with the c.s.f. in the subarachnoid space. Some vacuoles in addition showed openings on their apical surface thus constituting transcellular channels or pores. Basal openings up to 3·5 μm and apical openings up to 2·3 μm were seen.4. It is postulated that vacuoles are stages in the formation of a dynamic system of transcellular pores which allow the bulk outflow of c.s.f. down a pressure gradient, and that the mesothelial vacuolation cycle, in providing the requisite number of transcellular pores across the mesothelial barrier at any time, is a controlling factor in the outflow of c.s.f. and in the maintenance of its fluid‐pressure within the subarachnoid space.5. The basic similarity between the bulk flow of the aqueous humour and c.s.f. from the anatomically closed cavities of the anterior chamber and the subarachnoid space, respectively, is underlined.6. The present study provides further support for our hypothesis that the bulk outflow of fluid, via a dynamic system of transcellular pores formed by gradually enlarging membranous surface infoldings in a single cell, termed as giant vacuoles, is a fundamental biological process not hitherto described.
Membrane currents and activation of contraction in rat ventricular fibres
Authors: Léoty Claude 
Published: December 2014

1. A double sucrose gap technique has been combined with an optical method of measuring the movement of the preparation and applied to rat ventricular trabeculae.2. Experiments performed in normal McEwen and in depleted sodium solutions with and without tetrodotoxin, manganese or predepolarization suggest that the fast inward current is not as important as the slow inward current in determining the contractile strength. Furthermore, there is a marked similarity between potential dependence of the slow inward current and the contraction, particularly in sodium‐depleted fluids.3. The appearance of a staircase response associated with a series of depolarizations, in normal McEwen, may mean that there is an intervention of a further, possibly intracellular, stage between inward current and contraction, as suggested by earlier experiments on frog as well as on mammalian heart.
Drinking and antidiuresis elicited by isoprenaline in the dog
Authors: Fitzsimons J. T. , Szczepańska‐Sadowska Ewa 
Published: December 2014

1. Isoprenaline hydrochloride injected subcutaneously or infused intravenously caused drinking and simultaneous antidiuresis in the dog. The minimal effective dose was between 20 and 50 μg per dog.2. Isoprenaline‐induced drinking was prevented by the β‐adrenergic antagonist propranolol and enhanced by the α‐antagonist phentolamine.3. Ganglionic blockade with pentolinium or with hexamethonium did not interfere with the response.4. A delay of 1 hr after injection of 100 μg isoprenaline, before drinking was permitted, did not significantly reduce the amount of water subsequently drunk. A preload of water approximately equal to the volume of water normally drunk caused a greater reduction in water intake in some dogs.5. Isoprenaline caused an increase in heart rate and pulse pressure which lasted for between 1 and 3 hr according to dose. Central venous pressure fell, but mean arterial pressure was little altered. Haemodynamic changes preceded drinking by about 5 min.6. Infusion of isoprenaline caused drinking in the bilaterally nephrectomized dog.7. We conclude that isoprenaline is a potent stimulus to drinking in the dog and that the effect is not exclusively mediated by the renin‐angiotensin system.
Specific membrane properties of cat motoneurones
Authors: Barrett J. N. , Crill W. E. 
Published: December 2014

1. Electrophysiological properties of cat motoneurones were measured using intracellular electrodes, after which Procion dye was injected iontophoretically into the neurone through the recording pipette.2. Histological procedures were chosen to minimize changes in neuronal morphology. Reconstructed motoneurones had more dendritic branches and larger surface areas than the Golgi‐stained motoneurones of earlier reports.3. The sum of the 3/2 power of the dendritic diameters (the dendritic trunk parameter; Rall, 1959) of the reconstructed motoneurones was found to decrease with distance from the soma. Thus, the dendritic tree is not satisfactorily approximated by a non‐tapering membrane cylinder.4. A computational technique was developed to allow calculation of the specific resistance (Rm) of the membrane using the measured value of the input resistance of the motoneurone and a more detailed approximation of the dendritic tree. These calculations indicate that the average resting value of dendritic Rm is at least 1800 Ω cm2. The specific membrane capacity, calculated assuming uniform Rm, ranged between 2–3 μF/cm2.
Studies on laryngeal calibre during stimulation of peripheral and central chemoreceptors, pneumothorax and increased respiratory loads
Authors: Dixon M. , Szereda‐Przestaszewska Małgorzata , Widdicombe J. G. , Wise J. C. M. 
Published: December 2014

1. The effects of asphyxia, hypoxia, hypercapnia, stimulation of peripheral chemoreceptors, pneumothorax and breathing through resistances have been investigated on laryngeal resistance to airflow in anaesthetized cats, with and without bilateral vagotomy below the origin of the recurrent laryngeal nerves.2. Resistance to airflow of the innervated larynx was usually measured with the larynx isolated in situ with constant flow from the trachea to a pharyngeal opening, and expressed by the relationship between translaryngeal pressure and airflow.3. Asphyxia, hypoxia and hypercapnia each stimulated breathing and decreased laryngeal resistance to airflow, in both the inspiratory and expiratory phases. After vagotomy the effect was reduced, abolished or (usually) reversed to a laryngeal constriction, especially in expiration.4. Intra‐arterial injections of potassium cyanide (to stimulate carotid body chemoreceptors) caused a short apnoea or an augmented breath followed by hyperpnoea, concurrently with expiratory constrictions of the larynx. The responses were usually stronger after bilateral vagotomy.5. Pneumothorax caused tachypnoea, inspiratory dilatations and expiratory constrictions of the larynx. The responses were abolished by vagotomy.6. Imposition of respiratory resistances dilated the larynx, in inspiration and expiration, while complete closure of trachea caused expiratory constrictions of the larynx. These changes did not depend on intact vagal pathways.7. The results are discussed in terms of nervous control of the larynx in the different conditions.
Desensitization in the process of histamine secretion induced by antigen and dextran
Authors: Foreman J. C. , Garland L. G. 
Published: December 2014

1. Antigen challenge of sensitized rat peritoneal mast cells in the absence of calcium failed to release histamine. The release when calcium was added subsequently declined rapidly, this desensitization being almost complete in 4 min.2. Phosphatidyl serine (10 μg/ml.) reduced the rate of desensitization so that decay of the response to added calcium was not complete after 16 min.3. Exposing normal cells to dextran resulted in a slow rate of desensitization, the response to phosphatidyl serine added with calcium having decayed by only 27% within 10 min.4. Phosphatidyl serine added with dextran prevented desensitization so that the response to subsequently added calcium did not decay even after an interval of 20 min.5. Cells activated by dextran and calcium became rapidly desensitized as shown by decay of the response to added phosphatidyl serine which was almost complete by 5 min.6. Histamine release by the calcium ionophore (A 23187) added to cells at intervals before the addition of calcium did not show significant decay.7. Desensitization of the cells to antigen did not change their response to the ionophore.
The kinetics of pancreatic amylase secretion and its relationship to volume flow and electrical conductance in the anaesthetized cat
Authors: Greenwell J. R. , Scratcherd T. 
Published: December 2014

1. Enzyme secretion in response to short duration vagal stimulation or to rapid
I.V. injections of cholecystokinin‐pancreozymin (CCK‐PZ) or gastrin or to intra‐arterial injections of acetylcholine is a function of the volume of juice secreted and not primarily a function of time.2. The output of amylase in response to each stimulus occurred in a constant volume of approximately 15 drops (0·5 ml.) regardless of the rate of background secretin stimulated flow of water and electrolyte.3. It is argued that because amylase secretion occurs in this constant volume, it is due to the rapid secretion of enzyme into the duct system from the acini, and subsequently the secretin stimulated secretion of water and bicarbonate washes the enzyme from the duct system.4. When enzyme secretion is stimulated an increase in the electrical conductance (measured at 1·592 kHz) occurs across the tail of the pancreas. This increased conductance has two components. An early peak associated with the extrusion of enzyme from the acinar cell and a later peak which is probably due to vasodilatation.5. Atropine was without effect on both enzyme secretion and the conductance record when the stimulant was CCK‐PZ.Atropine blocked enzyme secretion and both peaks of the conductance record in response to stimulation by acetylcholine.Atropine blocked enzyme secretion and abolished the early phase of the conductance record, on vagal stimulation. It was without effect on the later peak which probably indicates an atropine resistant vasodilation of the pancreatic vessels.6. When the vagus is stimulated on a background of submaximal electrolyte secretion caused by the intravenous infusion of secretin, the volume rate of secretion and the rate of amylase secretion follow a similar time course. The maximal volume response occurred between 7 Hz and 15 Hz and the maximal amylase output per impulse was at 5 Hz.
The distribution in the rabbit of choline administered by injection or infusion
Authors: Gardiner J. E. , Gwee M. C. E. 
Published: December 2014

1. The concentration of choline in plasma, erythrocytes, skeletal muscle, heart, lung, liver, small intestine and kidneys and the changes that follow the injection or infusion of choline have been measured in rabbits anaesthetized with pentobarbitone.2. The concentration of choline in the plasma of arterial blood was 11·8 ± 0·6 n‐mole/ml. and in the erythrocytes 28·4 ± 1·3 n‐mole/ml. blood.3. All tissues contained a higher concentration of free choline than did plasma. The values range from 19·1 ± 2·2 n‐mole/g in skeletal muscle to 500 ± 25 n‐mole/g in the kidney.4. In order of their choline concentrations the tissues were intestine (duodenal end) > kidney > intestine (caecal end) > liver > lung > brain > heart > erythrocytes > (blood) > skeletal muscle > plasma, while in order of the contribution to the total body choline they were liver > intestine > skeletal muscle > (blood) > kidney > erythrocytes > lung > brain > plasma > heart. The total free choline determined by these analyses was between 30–40 μmole/kg body weight, about one third being present in the liver.5. The choline content of the small intestine varied along its length. The lowest amount being present in the portion adjoining the caecum.6. Within 1 min of the injection of choline 100 or 300 μmole/kg, 70–90% had left the circulation. The proportionate loss was higher after 100 μmole/kg than after 300 μmole/kg.7. The loss following 300 μmole/kg was increased if that dose were preceded by a dose of 100 μmole/kg 40 min earlier; this suggests some additional disposal mechanism(s) had been activated by the first dose.8. Three minutes after the injection of choline 300 μmole/kg, about 60% was present as free choline in the tissues studied. The order of the concentration increases was kidneys > liver > muscle > lung > small intestine (caecal end) > heart > intestine > small intestine (duodenal end) > brain.9. Forty minutes after the injection of choline 300 μmole/kg, only 11% could be accounted for as free choline. Only the levels in the kidney, liver, muscle and lung were significantly above normal at this time.10. Infusion of choline 0·8 μmole/kg. min or greater produced rises in plasma choline that corresponded to a clearance of 32 ml. plasma/kg. min.11. After the infusion of 300 μmole/kg over a period of 1 hr, raised levels of choline were detected in all tissues assayed, but the amount found accounted for only 14% of the choline administered. The concentrations in the kidney, liver and lung were similar to those found 40 min after the injection of 300 μmole/kg.12. There was no change in the concentration of choline in the erythrocytes after the injection of choline 100 or 300 μmole/kg, nor during the infusion of choline at the rate of 5 μmole/kg. min for 1 hr.13. The plasma volume appeared to be affected by the injection of the large doses of choline; after choline 300 μmole/kg the plasma volume was reduced. No effect on the plasma volume was observed during the infusion of the same dose.
Structure and function in urinary bladder of foetal sheep
Authors: France Venetia M. , Stanier Margaret W. , Wooding F. B. P. 
Published: December 2014

1. The structure and function of the epithelial lining of the urinary bladder of sheep foetuses was investigated by electron microscopic studies made in conjunction with a series of experiments in which the permeability of the bladder to sodium and water was measured in vitro. Measurements were made at gestational ages ranging from 50 to 141 days (term = 147 days) Osmolarity and electrolyte concentrations of urine found in the foetal bladder were also measured.2. The development of tight junctions between the bladder epithelial cells was investigated by incubating the tissue with solutions containing 1 m
M‐LaCl3 on the mucosal surface. No penetration of the junctions by lanthanum was observed in foetuses of 90 days or older. In younger bladders, the epithelial layer was stripped by treatment with lanthanum, but tight junctions appeared to be fully developed in early bladders incubated without lanthanum.3. The surface structure of the luminal (mucosal) plasmalemma was fully developed at 50 days.4. Unidirectional fluxes of labelled sodium and water were measured with identical solutions bathing the two surfaces of the bladder wall. No net water movement occurred; the mean ratio of efflux to influx in nine bladders was 1·002 ± 0·039 (
S.E. of mean). Under these conditions, the flux ratio for sodium was 1·735 ± 0·143 (
S.E. of mean) in twelve bladders.5. Antidiuretic hormone (ADH) had no effect on net water movement but reduced the net efflux of sodium so that the flux ratio became 1·285 ± 0·255 (
S.E. of mean) n = 8. ADH also had a striking effect on the structure of the epithelium, causing marked swelling of the intercellular spaces. The tight junctions remained an effective barrier to lanthanum penetration under these conditions; lanthanum was not observed in the enlarged spaces.
Determination of membrane potentials in human and Amphiuma red blood cells by means of a fluorescent probe
Authors: Hoffman J. F. , Laris P. C. 
Published: December 2014

1. Changes in the fluorescent intensity of the dye, 3,3′‐dihexyl‐2,2′‐oxacarbocyanine, added to suspensions of human and Amphiuma red blood cells were measured in parallel with changes in the membrane potentials of these cells. In these studies the membrane potential was altered in three different ways: by the addition of valinomycin to alter the ratio, PK/PCl, by a change in the pH of the medium to alter the ratio, Clc/Cl0, and by the substitution of impermeant anions for Cl0 again to alter the ratio, Clc/Cl0. In each case hyperpolarization led to a decrease and depolarization to an increase in fluorescent intensity.2. The change in fluorescence with the addition of valinomycin was dependent on the concentration of K in both the cells and the medium. Changes in fluorescence were not observed when valinomycin was added to suspensions of frozen‐thawed, haemoglobin‐free ghosts with dye in KCl or NaCl solutions. Such changes were observed with reconstituted ghosts provided that there was a K concentration gradient across the membrane.3. From values of cellular K and the corresponding external K concentrations for which there were no changes in fluorescence with valinomycin, estimations of membrane potentials were made. The potential was −5 to −8 mV for the human red cell and −19 mV for Amphiuma. These values are in good agreement with the potentials estimated from the Cl ratios (−9 mV for human and −17 to −20 mV for Amphiuma) and from those obtained by direct electrical measurements (−15 mV for Amphiuma).4. Fluorescent intensity of the dye in suspensions of human red cells was shown to be a linear function of the log Clc/Cl0.5. The dye (2·9 × 10−6
M) increased the inward rate constants for 24Na (3‐4‐fold) and 42K (0·5‐2‐fold) for human red cells. In addition, the dye was found to be haemolytic (5–6% in 1 hr) at 22° C.6. In contrast, the dye did not alter the rate of 35SO4 efflux at 37° C from human red cells previously equilibrated with a Cl‐free SO4 medium.7. The dye was also seen to interact with certain impermeant anions and other compounds, e.g. inhibitors of anion permeability, of interest. These interactions and other limitations of the use of this dye are discussed.
Temperature sensitivity of the paw of the cat: a behavioural study
Authors: Finger Stanley , Norrsell Ulf 
Published: December 2014

1. Cats were trained to respond to differences between the temperatures of the floors of two corridors of a modified T‐maze for a food reward.2. The cats were able to respond to differences between warm temperatures or differences between cool temperatures in the range of 1° C.3. Both warm and cool discriminations were mediated by receptors located in or near the footpads.4. The paw of the cat thus appears to be more sensitive to temperature changes than was believed previously, and its temperature sensitivity may be comparable to that of the hand of the primate.
On facilitation of transmitter release at the toad neuromuscular junction
Authors: Balnave Ron J. , Gage Peter W. 
Published: December 2014

1. The time dependence of the increase in amplitude (facilitation) of a second end‐plate potential (e.p.p.) elicited within 10–100 msec of a preceding e.p.p. was examined at neuromuscular junctions in sartorius muscles of toads. Facilitation was defined by two characteristics, initial facilitation and the time constant of its exponential decay.2. The time constant of decay of facilitation was longer at lower temperatures and the Q10 was 4·3 in the range 10–25° C. There was no significant effect of temperature on initial facilitation.3. Ouabain (10−4‐10−3
M), lithium substitution for sodium, sodium azide (5 m
M) and N‐ethylmaleimide (NEM, 0·1 m
M) initially had no effect on initial facilitation or the decay of facilitation. After some time, they all caused a longer time constant of decay of facilitation and a depression of initial facilitation.4. It was concluded that the decay of facilitation is not directly dependent on active transport of sodium ions, calcium efflux, ATP‐dependent movements of calcium or mitochondrial uptake of calcium following an action potential.5. Ouabain, lithium, sodium azide, and NEM all caused an increase in transmitter release. This effect, and the late effects on facilitation, were thought to be due to an increase in intracellular calcium concentration in nerve terminals.6. No relationship was found between the quantal content of e.p.p.s (range, 0·8‐100) and initial facilitation, or the time constant of decay of facilitation.7. Substitution of strontium for calcium ions caused a marked prolongation of the time constant of decay of facilitation, and a depression of initial facilitation.8. The results were consistent with the hypothesis that the time constant of decay of facilitation is related to the rate of disappearance of an ‘active’ complex of calcium (CaA) which, of itself, is not sufficient for transmitter release. It is suggested that an action potential produces CaA which decays with the time constant of facilitation and CaS, a short‐life complex of calcium which decays with the time constant of the phasic release of transmitter. The release of transmitter is proportional to some function of [CaA] and [CaS].
Twitch potentiation by potassium contractures in single muscle fibres of the frog
Authors: Chiarandini D. J. , Stefani E. 
Published: December 2014

1. The modifications of isometric twitches after K contractures have been studied in single muscle fibres from frog muscles.2. The twitch was greatly enhanced and somewhat prolonged after a conditioning K contracture. This potentiating effect was more evident in fibres having low values of the ratio control twitch tension/tetanus tension (P/P0).3. In most of the fibres, the time course of the decay of the potentiation phenomenon could be represented by the sum of three negative exponentials with average half‐times of 9·1, 40 and 485 sec.4. Between 3 and 10 min after the onset of the twitch potentiation the resting potential and action potential were unchanged.5. Mn blocked the K contractures and prevented the onset of the twitch potentiation.6. 40–140 sec after inducing a K contracture with 30 or 40 m
M‐K, a second exposure to the same [K] evoked a tension equivalent only to 57% of the first one. This partial refractoriness of the fibres is not seen when both contractures were elicited with 190 m
M‐K, and contrasts with the full recovery and potentiation of the twitch after a K contracture.