bluuebunny/crossref_metadata_2025_split huggingface dataset:
The pattern and control of sweating in the sheep and the goat
Authors: Robertshaw D. 
Published: December 2014

1. The pattern and control of sweating in one breed of goat and six breeds of sheep have been studied.2. Heat exposure of both sheep and goats resulted in periodic discharges of moisture on to the surface of the skin of the shorn mid‐side. The frequency of discharge showed considerable variation between individual animals, varying from less than 1/hr to 14/hr. Approximate counts of the number of active sweat glands suggested that the same glands were involved at each discharge.3. The amount of moisture produced at each discharge declined upon continued heat exposure. The rate of decline was independent of the frequency of discharge.4. Adreno‐medullary denervation had no effect on the pattern of sweating in either the sheep or the goat.5. Intravenous adrenaline administration (5 μg/kg body wt.) caused the sweat glands to discharge, but noradrenaline had no effect at the same dose.6. Thermal sweating was inhibited by bethanidine and phenoxybenzamine but not by propranolol. Sweating induced by intravenous adrenaline administration was blocked by phenoxybenzamine but not by bethanidine or propranolol.7. It is concluded that sweating on the mid‐side of the sheep and goat is controlled by an adrenergic mechanism, that secretion from the adrenal medulla under conditions of mild heat stress does not stimulate the glands and that sweating is mediated by adrenergic α‐receptors.
Prereceptor colour vision distortions in protanomalous trichromacy
Authors: Alpern M. , Torii S. 
Published: December 2014

1. Scotopic luminosity and fundus spectral reflexion in the protanomalous fail to confirm predictions made from the hypothesis that protanomalous photopic luminosity loss is due to an inert red‐absorbing filter in his ocular media.2. If it were supposed that the luminosity losses were due to a reduced number of normal red cones, the anomaloscope mismatches could result from a prereceptor distortion such as a reduced concentration of macular pigment or a tilt of the foveal cones. Experiments exclude these two possibilities.3. An anomaloscope is described which makes it possible to measure colour‐matching properties of the protanomalous eye by transcleral illumination. Such measurements exclude, as a class, hypotheses which attribute protanomalous colour‐matching distortions to an inert filter localized anywhere between the cone outer segment and the cornea.4. It is concluded that the absorption spectrum of at least one of the three cone visual pigments of the protanomalous eye must differ from that of the pigments of the normal fovea.
Passive electrical properties of rod outer segments
Authors: Falk Gertrude , Fatt P. 
Published: December 2014

1. Measurements on a packed suspension of randomly oriented, dark‐adapted frog rods at frequencies of 15 c/s‐0·5 Mc/s indicate a behaviour similar to that of other biological materials.2. Results are analysed on the assumption that the low‐frequency limiting resistance is determined by current flowing in the suspending medium and that, of the rods, two thirds are oriented perpendicular to the applied field and one third parallel to it. Those parallel to the field are treated as non‐conductors.3. From the high‐frequency limiting resistance the conductivity of the rod interior is calculated to vary linearly with the conductivity of the medium. The slope of the relation of internal to external conductivity is 0·50 with a limiting internal conductivity (at zero external) of 280 μmho/cm.4. On the assumption that the suspension can be represented as a single‐capacitance network, the characteristic frequency of impedance is used to calculate a capacitance for the rod surface of 1·54 μF/cm2. On the assumption of a distribution in properties of the suspension according to the theory of Bruggeman, the capacitance is calculated to have a value of about one half this.5. At frequencies below 5 kc/s the impedance locus deviates from the curve describing the behaviour at higher frequencies. It is suggested that this may involve conduction in a thin layer extending along the surface of the rod.
A study of the mechanism of quantal transmitter release at a chemical synapse
Authors: Blioch Zhanna L. , Glagoleva Irina M. , Liberman E. A. , Nenashev V. A. 
Published: December 2014

1. The nerve‐muscle preparation of the cutaneous pectoris of the frog has been used to study quantal transmitter release.2. When the osmotic pressure of the external solution is raised 1·5‐2 fold, the frequency of miniature end‐plate potentials (m.e.p.p.s) rises by 1·5‐2 orders of magnitude. This effect is independent of the presence of Ca2+ ions and of the nature of the substances by which the osmotic pressure has been increased.3. In Ca2+ free hypertonic solution the nerve impulse still invades the nerve terminals but does not alter the frequency of the m.e.p.p.s.4. The arrival of the impulse in the terminals causes an immediate increase in the rate of quantal release, provided divalent cations are present whose passage through the axon membrane is facilitated by excitation (Ca2+, Sr2+, Ba2+).5. Divalent cations which penetrate only slightly (Mg2+, Be2+) lower the frequency of m.e.p.p.s and suppress the end‐plate potential (e.p.p.) evoked by an impulse, in the presence of Ca2+ ions. Be2+ is a more effective inhibitor than Mg2+.6. In Ca2+ free solutions, adding Mg2+ causes an increase in the frequency of m.e.p.p.s evoked by depolarization of the nerve endings or by treatment with ethanol.7. The trivalent cation La3+ is more effective than divalent cations are in increasing the frequency of m.e.p.p.s. The tetravalent cation Th4+ also raises the m.e.p.p. frequency.8. The observations summarized in paragraphs 2‐7 indicate that the frequency of m.e.p.p.s at a constant temperature depends only on the concentration of uni‐, di‐ and trivalent cations inside the nerve ending. It is suggested that the internal cation concentration influences the adhesion between synaptic vesicles and the membrane of the nerve ending.9. For a model experiment, artificial phospholipid membranes have been used to study the effect of uni‐, di‐, tri‐ and tetravalent cations on the adhesion process. At pH 7‐7·4, the time required for adhesion to take place decreases with increasing cation concentration in the bath. Ca2+ ions are 100‐1000 times more effective than K+ ions; La3+ and Th4+ ions are still more effective. The ‘adhesion time’ decreases when the pH is lowered; it increases greatly with lowering of temperature.10. The hypothesis is put forward that the mutual adhesion of artificial vesicles made of phospholipid membranes, and the adhesion between synaptic vesicles and the membrane of the nerve ending arise by a common mechanism. In both cases, the important factor is the influence of cations on the electric double layer at the membrane surface.
Disaccharide absorption by amphibian small intestine in vitro
Authors: Parsons D. S. , Prichard J. S. 
Published: December 2014

1. An account is given of the absorption of disaccharides by the small intestine of Rana temporaria, R. pipiens and Bufo vulgaris perfused in vitro through the vascular system. Maltase and trehalase activity are found in the intestine of all three species; very small amounts of sucrase are present in the intestine of R. pipiens but there is no evidence for the presence of lactase in any of the animals studied.2. During maltose absorption free glucose appears in the vascular effluent and in the intestinal lumen. Only very small quantities of disaccharide are found in the vascular effluent. The concentration of free glucose in the intestinal lumen during maltose absorption is not high enough to account for the rates of glucose transport observed. The rate of appearance of glucose in the vascular effluent is determined by the concentration of disaccharide in the luminal fluid, and hexose, free in solution in the lumen, is not an obligatory intermediate in the process of disaccharide absorption.3. For R. pipiens more than 90% of the maltase activity in the system is present in the intestinal wall and the rate of maltose hydrolysis by maltase, free in the intestinal lumen, is found to be inadequate to account for the rates of appearance of glucose observed to occur in the lumen and in the vascular effluent. It is not possible to wash away maltase activity from the intestinal wall.4. The kinetic properties of maltase and trehalase acting in situ are of the Michaelis—Menten type; the apparent Km is 2 m
M for maltase, and 3 m
M for trehalase.5. The relationship which exists between the rate of absorption of glucose and the concentration in the luminal fluid of either disaccharide or free glucose is of the Michaelis—Menten type. Expressed in molar units, the apparent Km for the glucose transport is about one fifth that of the disaccharidase. The maximum rate of glucose transport observed is less than the maximum rate of disaccharide hydrolysis. In R. pipiens equimolar concentrations in the intestinal lumen of the monomer free glucose, or of the dimer, maltose, yield approximately equal rates of transport of the free hexose.6. It is concluded that in the amphibian, either intestine disaccharide hydrolysis and glucose transport are functions of separate subcellular systems which spatially are very closely related, or that the hydrolysis and transport are different facets of the activity of a common system.
Cations and the secretion of insulin from rabbit pancreas in vitro
Authors: Hales C. N. , Milner R. D. G. 
Published: December 2014

1. Insulin secretion from pieces of rabbit pancreas incubated in vitro was studied in media of different ionic compositions.2. Insulin secretion stimulated by glucose was abolished by removal of calcium from the incubation medium and inhibited by a twofold rise in the calcium concentration to 10·2 m‐equiv/l. Removal of magnesium from the medium did not affect glucose‐stimulated secretion but a tenfold rise in the extracellular magnesium concentration to 24 m‐equiv/l. abolished secretion.3. The replacement of calcium by an equivalent amount of barium (5·1 m‐equiv/l.) stimulated insulin secretion. Barium stimulation declined with time and was inhibited by the presence of calcium, 5·1 m‐equiv/l., or abolished by the presence of magnesium, 24 m‐equiv/l., in the incubation medium.4. The interactions of mono‐ and divalent cations on insulin secretion were studied by using ouabain or potassium as tools to raise intracellular sodium concentration and barium as a calcium analogue. Ouabain and potassium were effective stimuli only in the presence of calcium, and barium only stimulated insulin secretion in the presence of sodium.5. The results of these experiments suggest that both calcium and sodium must act at the β cell membrane or enter the cell before insulin release can occur in response to a variety of stimuli.
Circulatory effects of chloralose‐urethane and sodium pentobarbitone anaesthesia in the rabbit
Authors: Korner P. I. , Uther J. B. , White S. W. 
Published: December 2014

1. The effects of chloralose‐urethane and sodium pentobarbitone anaesthesia on heart rate, blood pressure and cardiac output were studied in normal rabbits, in animals given atropine and in animals without functioning autonomic effectors. The findings under anaesthesia were compared during spontaneous and artificial intermittent positive pressure respiration.2. The circulatory effects of chloralose‐urethane and sodium pentobarbitone anaesthesia differed significantly for the first hour after induction of anaesthesia. During the subsequent 3 hr of maintained anaesthesia differences in the circulatory effects of the two anaesthetics were small.3. The direct local effects of these anaesthetics were assessed during the maintenance phase from the responses of animals without functioning autonomic effectors. With both anaesthetics there was peripheral vasodilatation and minimal effects on heart rate.4. The autonomic activity in the normal animal was assessed by comparing the changes in normal, atropinized and ‘de‐efferented’ rabbits without functioning autonomic effectors. During chloralose‐urethane anaesthesia there was reduction in cardiac vagal efferent activity and no change in cardiac sympatho‐adrenal activity. With both anaesthetics there was an increase in peripheral sympatho‐adrenal constrictor activity, tending to minimize the local vasodilator effects.
Are there two types of deuteranopes?
Authors: Alpern M. , Mindel J. , Torii S. 
Published: December 2014

1. The colour vision of a Type I deuteranope who fulfils both of Willmer's criteria (normal foveal luminosity curve, two cone mechanisms in the central fovea revealed by a small 10′ test flash) has been studied.2. Spectral sensitivity curves (at threshold) on bright red or green backgrounds are identical in the red‐green range.3. Heterochromatic brightness‐match luminosity curves measured after bright red or green bleaches are identical in the red‐green range.4. Study of prereceptor light losses show normal colour of the ocular media; spectral reflexion coefficient measurements reveal no evidence of macular pigment.5. Luminosity curves measured through a filter which artificially replaces the missing macular pigment is identical to the deuteranopic (Type II) curve. Lack of macular pigment explains the ‘normal’ luminosity curve.6. Red and violet backgrounds raise the thresholds for 10′ red and violet tests by different amounts because two cone (the red and the blue) mechanisms are concerned.7. Reducing the size of the test to 4′ eliminates the contribution of the blue cone mechanism to threshold. Now only the red mechanism determines the threshold.8. It is concluded that this subject has only a single red‐green cone pigment, normal erythrolabe, like other (Type II) deuteranopes.
Local activation of frog muscle fibres with linearly rising currents
Authors: Sugi H. 
Published: December 2014

1. Single fast muscle fibres isolated from the semitendinosus muscles of the frog were locally activated by applying linearly rising current pulses to a pipette whose tip (diameter, 10‐40 μ) was in contact with the fibre surface.2. In normal or choline‐Ringer solution with 1·8 m
M‐Ca, the threshold depolarization for producing a just perceptible local contraction was nearly constant over a wide range of the duration of linearly rising currents (0·5‐20 sec or more).3. If [Ca]o was reduced to 0·25‐0·1 m
M, the threshold depolarization increased steeply with the increase in the duration of linearly rising currents, indicating a marked increase in the rate of an accommodation process in excitation‐contraction coupling mechanism.4. In the low‐Ca media, the threshold depolarization was observed to rise exponentially during the application of a linearly rising current of 3‐10 sec duration, and to return exponentially to its initial value within 3‐10 sec after the removal of the current.5. The marked accommodation in the low‐Ca media was partially inhibited by the addition of Mg (5‐10 m
M), and completely eliminated in the presence of caffeine (1 m
M), suggesting that the accommodation process may occur in the link between membrane depolarization and release of Ca from sarcoplasmic reticulum.6. Microscopic observation of local contractions in the low‐Ca media indicated that the accommodative rise of threshold depolarization was most marked at the superficial layer of the fibre.7. From these results, it is suggested that the removal of bound Ca or some other kind of charged particle from the transverse tubular system or from its vicinity might be the cause of accommodation in excitation‐contraction coupling.
Independent action of antidiuretic hormone, theophylline and cyclic 3′,5′‐adenosine monophosphate on cell membrane permeability in frog skin
Authors: Cuthbert A. W. , Painter Elisabeth 
Published: December 2014

1. The effects of antidiuretic hormone (ADH), theophylline and cyclic 3′,5′‐adenosine monophosphate (AMP) on membrane potentials in frog skin have been investigated.2. Membrane potentials across the outer and inner facing membranes were recorded in both normal and current clamped skins. In the latter condition active transport of sodium had been abolished by ouabain or metabolic inhibitors, but ionic gradients were maintained by passing current through the skin from the inside.3. ADH increases the potential across the outer facing membranes and reduces the skin resistance. The results are consistent with ADH causing an increase in permeability of the outer facing membranes to sodium ions.4. Theophylline reduces the skin potential by reducing specifically the potential across the outer facing membranes. At the same time the skin resistance is reduced. Theophylline acts by increasing the permeability of the outer facing membranes to chloride ions.5. Cyclic 3′,5′‐AMP causes a biphasic potential change accompanied by an increase in skin resistance.6. Metabolic inhibitors block the response of the skin to ADH but not to theophylline.7. Separate explanations for the increase in sodium transport by ADH, theophylline and cyclic 3′,5′‐AMP are discussed. It is not necessary to involve cyclic AMP in order to explain the effects of either ADH or theophylline.
A quantitative study of cholinesterase in myoneural junctions from rat and guinea‐pig extraocular muscles
Authors: Buckley G. A. , Heaton J. 
Published: December 2014

1. Cholinesterase staining of rat and guinea‐pig extraocular muscle shows focally and multiply innervated fibres.2. The distribution of cholinesterase activities in the populations of focal endings (from singly innervated fibres) and fine motor endings (from multiply innervated fibres) was determined by a sensitive radiochemical method.3. Focal endings had a greater cholinesterase activity than fine motor endings.4. It is suggested that this difference in enzyme activities is related to the functional difference between twitch and slow fibres in extraocular muscle.
Muscular, bronchomotor and cardiovascular reflexes elicited by mechanical stimulation of the respiratory tract
Authors: Tomori Z. , Widdicombe J. G. 
Published: December 2014

1. The effects of mechanical stimulation in the nose, epipharynx, laryngopharynx and tracheobronchial tree, and of chemical irritation of the nasal mucosa, were studied on various somatic and autonomic functions in cats.2. Action potentials were recorded from the diaphragm and rectus abdominis muscles of spontaneously breathing cats, and from the phrenic and lumbar nerves of paralysed, artificially ventilated cats. Expulsive processes such as sneezing and coughing evoked from the nasal, laryngopharyngeal and tracheobronchial mucosae were characterized by strong diaphragmatic and abdominal expiratory discharges; synchronous discharges in these antagonistic respiratory muscles and their motoneurones often occurred especially during laryngopharyngeal stimulation of coughing.3. The ‘aspiration reflex’ elicited from the epipharynx was characterized by brief bursts of high‐frequency activity in the phrenic nerve and diaphragm, and was usually not followed by any expiratory activity in the rectus abdominis or its motoneurones.4. In paralysed, artificially ventilated cats stimulation of the laryngeal and tracheobronchial regions caused large increases both in total lung resistance and in tracheal constrictor nerve fibre activity, indicating reflex tracheo‐bronchoconstriction; similar stimulation of the epipharyngeal and nasal mucosae decreased both total lung resistance and tracheal constrictor nerve fibre activity, indicating reflex bronchodilation.5. In paralysed cats, stimulation of each of the four sites in the respiratory tract caused a reflex increase in systemic blood pressure, the largest hypertensive response coming from the epipharynx. Nervous activity in cervical sympathetic efferent fibres was increased by the stimulations, especially those of the epipharyngeal and laryngopharyngeal regions.6. There was good correlation in time and magnitude between the changes in total lung resistance and in bronchoconstrictor fibre activity, and also between the changes in blood pressure and in efferent sympathetic discharge, although the mechanical changes lagged behind the nervous ones.7. In anaesthetized, spontaneously breathing cats stimulation of the respiratory tract evoked large variations in blood pressure accompanying the spasmodic respiratory efforts, probably by mechanical effects.
Adaptation of the generator potential in the crayfish stretch receptors under constant length and constant tension
Authors: Nakajima S. , Onodera Kayoko 
Published: December 2014

1. Generator potentials were investigated in stretch receptors of crayfish after abolishing spike potentials with tetrodotoxin.2. The time courses of the decline of generator potential (generator adaptation) were almost the same in the slowly and rapidly adapting receptors.3. The time courses of the tension changes after suddenly stretching the receptor muscles did not differ much between the two receptor types.4. The amplitudes of generator potential per unit stress or per unit strain in the receptor muscle were roughly the same in the two receptor types.5. By comparing generator adaptation under length‐clamp and tension‐clamp in the slowly adapting receptors, it was suggested that roughly 70% of the generator adaptation could be explained by a simple visco‐elastic property of the receptor muscle, when observed for 1 sec after the beginning of the stretch.6. It was concluded that the marked differences in the receptor adaptation between the two receptor types were attributable to the differences in the properties of spike generating membrane rather than to the properties of the generator potentials.7. In each type of receptor, both the generator adaptation and the adaptation of spike generating mechanisms contributed to determining the whole rates of receptor adaptation. In the slowly adapting receptor, however, the generator adaptation seemed more important, while in the rapidly adapting receptor the spike generating mechanisms seemed more important.
The growth of the muscular and collagenous parts of the rat heart in various forms of cardiomegaly
Authors: Bartošová D. , Chvapil M. , Korecký B. , Poupa O. , Rakušan K. , Turek Z. , Vízek M. 
Published: December 2014

1. Cardiomegaly has been produced in rats by sideropenic anaemia, by isoprenaline or thyroxine or by the application of both drugs, by artificial increase in resistance to blood flow and by long‐term adaptation to hypoxia and physical stress. The ratio of the growth of muscle to the growth of collagen in the heart has been studied.2. All possible variations in the ratio occurred depending on the type of stimulus used for inducing cardiomegaly and on the dynamics of the development of cardiomegaly. In cardiomegaly induced by sideropenia and by thyroxine the growth of muscle was not accompanied by the growth of collagen. Exposure to hypoxia or isoprenaline administration increased only the growth of collagen in the hypertrophic heart. In all other forms of cardiomegaly muscle and collagen formation were stimulated to the same extent.3. It is concluded that when certain organs hypertrophy during adult life several factors may determine the relative rapidity of growth of the muscular or parenchymal and the collagenous stromal components of the tissue.