bluuebunny/crossref_metadata_2025 huggingface dataset:
Motor innervation of the coronary arteries of the cat
Authors: Brown A. M.
Published: December 2014

1. The effect on coronary vascular resistance of selective stimulation of the Aδ, B and sC fibre groups of the post‐ganglionic cardiac sympathetic nerves was studied. The main left coronary artery was perfused at constant flow. The oxygen saturation of coronary sinus blood was measured continuously.

2. Stimulation of the peripheral ends of the cut Aδ afferent fibres, normally excited by myocardial ischaemia, had no effect on coronary vascular resistance; these fibres do not evoke an axon reflex in the heart.

3. Stimulation of the preganglionic B fibres that run without synapse through the stellate ganglion also had no measurable effect on coronary resistance.

4. Stimulation of the post‐ganglionic sC fibres of the cardiac sympathetic nerves caused coronary vasodilatation which occurred earlier than, and was initially independent of the decrease in coronary sinus oxygen saturation.

5. The injection of noradrenaline into the perfusion system had the same effect as stimulation of the sC fibres. In the K+‐arrested heart, both noradrenaline and stimulation of the post‐ganglionic nerves elicited coronary vasodilatation without changing the oxygen saturation of coronary sinus blood.

6. The intracoronary injection of acetylcholine caused coronary vasodilatation followed by an increase of coronary sinus oxygen saturation.

7. Vagal stimulation caused brady cardia and a fall in coronary resistance.

8. Propranolol blocked coronary vasodilatation elicited by sympathetic stimulation or noradrenaline without affecting the vasodilatation due to myocardial ischaemia or acetylcholine. Atropine blocked coronary vasodilatation evoked by acetylcholine without affecting that due to ischaemia or noradrenaline. Therefore smooth muscle of the coronary arteries has at least three different receptor sites from which vasodilatation can be elicited.

9. Hypertensin caused coronary vasoconstriction.

10. The presence of sympathetic cholinergic vasodilator fibres innervating the coronary arteries could not be demonstrated.
The effects of insulin on the new‐born calf
Authors: Comline R. S. , Edwards A. V.
Published: December 2014

1. The normal variations in the concentrations of glucose, fructose and lactic acid in the blood of the calf which occur during the first few weeks after birth have been examined.

2. The responses of calves of different ages to intravenous injections of insulin have been examined by recording both the incidence of convulsions and the changes in the concentration of glucose, fructose and lactic acid in the blood.

3. New‐born calves rarely convulsed during prolonged and severe hypoglycaemia and, if convulsions occurred, the onset was delayed by 6‐8 hr. At 7 days of age convulsions usually followed the injection of insulin within 1½‐2 hr.

4. No relationship could be found between the duration of hypoglycaemia and the incidence of convulsions at different ages. Hypoglycaemia was most prolonged in new‐born calves which rarely convulsed.

5. Insulin hypoglycaemia during the first 24 hr after birth was associated with a rise in the concentration of lactate in the blood. Similar changes did not occur in calves at 7 days of age, in which the incidence of convulsions was much higher, or in weaned animals.

6. After both splanchnic nerves had been cut, insulin always caused convulsions in 24‐hr‐old calves. There was no rise in the blood lactate concentration in these animals.

7. Intravenous infusions of adrenaline but not noradrenaline in amounts similar to those known to be released from the adrenal medulla of the calf of this age prevented convulsions in 24‐hr‐old calves after section of the splanchnic nerves. These infusions had little effect on the blood glucose concentration but caused a similar rise in the lactic acid concentration to that found in normal animals at this age during hypoglycaemia.

8. At 7 days of age convulsions could only be prevented during hypoglycaemia by infusing larger doses of adrenaline which significantly raised the blood glucose concentration. The increase in the blood lactate concentration was less than that in the new‐born animals.

9. The resistance to insulin hypoglycaemia which occurs immediately after birth is transient; it depends upon the release of adrenaline from the adrenal medulla and is associated with high concentrations of lactate in the blood during hypoglycaemia.
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.
A model of thyroxine metabolism based on the effects on environmental temperature
Authors: Harland W. A. , Orr J. S.
Published: December 2014

1. Evidence is presented that, in rats, the whole body and plasma half‐lives of [131I]thyroxine are different.

2. It is shown that the whole body half‐life can be influenced by environmental temperature: plasma half‐life is influenced to a much lesser extent.

3. It is demonstrated that, in the rabbit, free labelled thyroxine and plasma bound labelled thyroxine leave the plasma at different rates when administered by intravenous injection.

4. It is deduced from the above and other evidence that the currently accepted view of thyroxine distribution and metabolism is invalid and a model compatible with the evidence is presented and discussed.

5. The essential feature of the model is that protein binding in plasma or in various tissues, once it has occurred, may be regarded as being irreversible and that no significant interchange takes place.

6. Indices of thyroxine metabolism are derived. These enable thyroxine content and turnover of the whole body or of individual organs to be measured.
Distribution and kinetics of CoEDTA in smooth muscle, and its use as an extracellular marker
Authors: Brading Alison F. , Jones A. W.
Published: December 2014

1. [60Co]EDTA has been evaluated as an extracellular marker in guinea‐pig taenia coli and rabbit myometrium.

2. The complex was found to be stable, non‐toxic, convenient to use and had the advantage of being readily measured without interfering with the analysis of water and electrolyte contents.

3. In both smooth muscles [60Co]EDTA distributed rapidly into a volume equivalent to that available to [14C]sorbitol and slightly greater than that available to inulin.

4. The optimum concentrations of carrier required to effectively saturate any adsorption sites were 0·1 m
M‐CoEDTA for taenia coli and 1·0 m
M for myometrium.

5. [60Co]EDTA was distributed into a volume equivalent to the total water content of rabbit tendon, indicating that it was not excluded from connective tissue water.

6. About 5% of the [60Co]EDTA taken up by smooth muscle in 15 minutes exhibited slow efflux kinetics. This property was also exhibited by [14C]sorbitol and has been reported for other extracellular markers.

7. The efflux of 95% of [60Co]EDTA followed bulk diffusion kinetics for both taenia coli and myometrium.

8. The simultaneous efflux of 24Na indicated that 1‐2% exchanged slowly while 98‐99% of the 24Na exchange could be described by bulk diffusion kinetics, similar to [60Co]EDTA. About 15% of this 24Na was contained outside of the [60Co]EDTA space.

9. More detailed studies involving the analysis of simultaneous efflux of [60Co]EDTA and 24Na may help to locate and characterize the properties of the excess rapidly exchanging sodium (12‐15 m‐equiv/kg. wet wt.) in smooth muscle.
Metabolism, sperm and fluid production of the isolated perfused testis of the sheep and goat
Authors: Linzell J. L. , Setchell B. P.
Published: December 2014

1. A total of nineteen ram and three goat testes have been perfused in isolation at 34–35° C for 3½‐9 hr with heparinized blood and an added 5‐HT antagonist (bromolysergic acid diethylamide) and their function compared with that of the normal ram testes in vivo.

2. The metabolism of the perfused testes and the testes in vivo was similar but blood flow through the perfused testes was two to three times normal.

3. Vasoconstriction was produced by adrenaline and noradrenaline (10–20 μg
I.A.) and by electrical stimulation of nerves in the spermatic cord or of the lumbar sympathetic chain; these responses were abolished or reduced by phenoxybenzamine.

4. Flow of fluid from the rete testis continued only if ischaemia was reduced to a minimum and glucose concentration in the blood perfusing the testis was kept above about 25 mg/100 ml.; the fluid secreted during perfusion was of normal composition.

5. The perfused testis showed no evidence of autoregulation and the flow of fluid was not affected by changes in perfusion pressure.

6. When the temperature of three testes was raised to 40° C for 2 hr, metabolism increased but blood flow was unaltered; the flow of fluid and the concentration of spermatozoa decreased during heating.

7. The testes perfused at normal scrotal temperatures (34–35° C) were histologically normal but some abnormalities were observed in the heated testes.
The longitudinal tissue impedance of the smooth muscle of guinea‐pig taenia coli
Authors: Tomita T.
Published: December 2014

1. The absolute value of the tissue impedance of the guinea‐pig taenia coli was measured in the longitudinal direction in air at 36° C. The relation between the tissue impedance and the separation of the recording electrodes indicated that the tissue has cable‐like properties. The frequency dependence of the impedance, observed at various distances from the current supplying electrode, showed that the tissue has a capacity component in the longitudinal direction.

2. The tissue impedance in the longitudinal direction was also measured while the tissue was suspended in a narrow tube at 25–28° C. The tissue impedance was calculated on the basis of the difference between the total impedance in Krebs solution and that in Krebs solution containing half the normal Na concentration, knowing the specific resistance of both solutions.

3. The impedance per unit volume of the tissue was 370 Ω cm at 10 c/s and 190 Ω cm at 10 kc/s; at these frequencies the impedance was nearly independent of current frequency. The difference between the impedances (370 — 190 = 180 Ω cm) was taken to be the impedance of the junctions between cells. The possibility of slightly lower values for the actual tissue impedance was discussed. The capacity located at or near the junction was calculated to be 1–3 μF/cm, the time constant of the junctional membrane being about 0·5 msec.

4. Ca ions (0–12·5 m
M) and adrenaline (2 × 10−7 g/ml.) had no measurable effect on the longitudinal impedance within 10–15 min. In hyperosmotic solution of twice osmolarity (by adding sucrose), the tissue impedance was increased by about 50%. When the tissue was immersed in sucrose solution containing no ions, the impedance gradually increased up to nearly 10 times in the course of 1 hr.
Transcellular transport of isosmotic volumes by the rabbit gall‐bladder in vitro
Authors: Frederiksen O. , Leyssac Paul P.
Published: December 2014

1. Fluid transport rate and oxygen consumption (QO2) were studied in rabbit gall‐bladder preparations in vitro exposed on both sides to identical Ringer solutions with NaCl concentrations (and osmolarities) varying from 70 to 140 m‐equiv Na+/l.).

2. The time sequence of acute effects on transport rate resulting from sudden changes in the NaCl concentration of the bathing solutions indicated that, (a) as a primary effect, fluid volume transfer rate remained unaffected whereas Na transport rate changed abruptly in direct proportion to the Na concentration of the bathing media; (b) a secondary, delayed and partly reversible depression of fluid transfer rate following elevation of the NaCl concentration was observed only when the rate of transport was relatively high initially.

3. A fixed, and highly significant, linear relationship between changes in transport‐linked oxygen consumption (ΔQO2) and measured net fluid volume transport (ΔTvol) was found independent of the NaCl concentration of the bathing media, dQO2/dTvol being 0·22 ± 11% and 0·25 ± 8% in bladders incubated in solutions containing 140 and 70 m‐equiv Na+/l. respectively.

4. Oxygen consumption per equiv of Na+ (calculated) transported varied in inverse proportion to the Na concentration of the bathing media, dQO2/dTNa being 0·0016 ± 11% and 0·0036 ± 8% in ‘140 R’ and ‘70 R’ solutions, respectively.

5. Removal of K from the bathing solutions was followed by a gradual and partly reversible depression of fluid transport rate to a minimum level (about 100 × 10−4 μl H2O. min−1.mg−1) independent of the initial transport rate.

6. It is concluded that the range of absorption rates of isosmotic fluid from the gall‐bladder lumen represents a range of energy requiring capacities for transfer of fluid volume units; the data suggest that the intracellular (cytoplasmic) ion composition, depending on the presence of external K, as well as hormonal action may influence the capacity of the transcellular fluid transport mechanism.

7. A model (a ‘mechanical volume pump’) for transcellular transfer of fluid volume units, allowing for flexible specificity with regard to the actively transported solutes, and requiring the presence of Na+ and Cl−, is proposed.
The effect of vagotomy, vagal cooling and efferent vagal stimulation on breathing and lung mechanics of rabbits
Authors: Karczewski W. , Widdicombe J. G.
Published: December 2014

1. The effects of bilateral cervical vagotomy, of bilateral vagal cooling and of efferent vagal stimulation were studied on rabbits anaesthetized with pentobarbitone sodium. Total lung conductance, lung compliance, breathing frequency, tidal volume, end‐tidal CO2%, systemic arterial and right atrial blood pressures and heart rate were measured. Some of the rabbits were first paralysed and artificially ventilated.

2. The changes in lung conductance were consistent with the presence of a tonic efferent vagal discharge in bronchoconstrictor fibres, reflexly damped down by a tonic afferent vagal discharge dilator to the airways, probably the Hering—Breuer inflation reflex.

3. Neither vagotomy nor efferent vagal stimulation significantly influenced lung compliance, right atrial pressure or end‐tidal CO2%; vagal cooling lowered end‐tidal CO2% in spontaneously breathing rabbits, but did not affect the other variables.

4. Efferent vagal stimulation in the rabbit decreased lung conductance with no significant change in lung compliance.

5. In the rabbit, vagal efferent activity affects primarily the larger (resistance) air passages with little action on the distal (compliance‐influencing) airways.
The role of the vagus nerves in the respiratory and circulatory responses to intravenous histamine and phenyl diguanide in rabbits
Authors: Karczewski W. , Widdicombe J. G.
Published: December 2014

1. The responses of rabbits, anaesthetized with pentobarbitone sodium, to intravenous injections of histamine and phenyl diguanide have been studied. Total lung conductance, lung compliance, breathing frequency, tidal volume, end‐tidal CO2%, systemic arterial and right atrial blood pressures and heart rate were measured. Some of the rabbits were first paralysed and artificially ventilated.

2. The role of vagal afferent nerves was determined by observing the responses before and after bilateral vagotomy, and before and during cooling the vagus nerves to 8–10° C; such cooling selectively blocks some vagal afferent pathways.

3. Histamine decreased conductance (bronchoconstriction), in spontaneously breathing and in paralysed, artificially ventilated animals, and caused rapid shallow breathing. The responses were considerably reduced or abolished by vagal cooling and vagotomy and are thought to be mainly vagal reflexes due to stimulation by histamine of irritant receptors in the lungs.

4. Phenyl diguanide also decreased conductance, in spontaneously breathing and in paralysed, artificially ventilated animals, and caused rapid shallow breathing. Vagotomy abolished the respiratory changes and considerably reduced the bronchoconstriction. Vagal cooling caused an equal reduction of the bronchoconstriction but an increase in minute volume persisted. This respiratory response to phenyl diguanide which persists during vagal cooling is thought to be due to stimulation of deflation receptors in the lungs; it was associated with vagal reflex hypotension and bradycardia.

5. Both histamine and phenyl diguanide decreased lung compliance when vagal conduction was unimpaired. The effects were largely secondary to changes in the pattern of breathing, although histamine also had a weak direct action on lung tissue leading to a fall in compliance.

6. Both histamine and phenyl diguanide decreased end‐tidal CO2% and increased right atrial pressure by direct (non‐vagal) actions on lung tissues. Histamine also caused a non‐vagal hypertension.
Wave‐length discrimination at the foveal chromatic threshold
Authors: Wilson M. E.
Published: December 2014

1. Wave‐length discrimination has been measured at the chromatic threshold to test the assumption that when a monochromatic stimulus is reduced to its chromatic threshold, the activity of a single cone mechanism may be isolated.

2. It has been shown that, at the chromatic threshold, all wave‐lengths between 559 and at least 665 mμ are significantly confused. Similar ranges of confusion extend from 457 to 570 mμ and from 485 to at least 419 mμ.

3. These results have been shown to be consistent with previous measures of the spectral sensitivities of the cone pigments. They support the view that the hue of a monochromatic stimulus at its chromatic threshold may be dependent on light absorbed by only one cone pigment.
Membrane current and intracellular sodium changes in a snail neurone during extrusion of injected sodium
Authors: Thomas R. C.
Published: December 2014

1. Sodium was injected into an identified snail neurone by passing current between two intracellular micro‐electrodes, the membrane potential being recorded with a third micro‐electrode.

2. The injection of about 25 p‐equiv Na, but not the injection of similar quantities of K or Li, caused a hyperpolarization of up to 20 mV. This response to Na injection was blocked by application of ouabain or removal of external K, indicating that it was due to the stimulation of an electrogenic pump.

3. To measure the current produced by the sodium pump the output of a feed‐back amplifier was fed into the cell via a fourth intracellular micro‐electrode so as to keep the average membrane potential constant. The pump current, measured in this way, rose at a constant rate during, and declined exponentially after, an injection of Na, the decline having an average time constant of 4·4 min. The total charge transferred by the pump was between a third and a quarter of the charge passed to inject sodium.

4. An intracellular Na‐sensitive glass micro‐electrode was used to follow changes in the concentration of intracellular Na ions. The results showed that both the pump current and the rate of Na extrusion were proportional to the concentration of intracellular Na ions above the normal level.

5. It was concluded that about two thirds of the Na extruded was coupled to the active transport of other ions, probably to the uptake of K, the uncoupled third producing the electrogenic effect.
The influence of activity on some contractile characteristics of mammalian fast and slow muscles
Authors: Salmons S. , Vrbová Gerta
Published: December 2014

1. The time course of contraction and relaxation in the isometric twitch of a rabbit soleus muscle becomes more rapid following tenotomy and spinal cord section. This increase in speed could be prevented by long‐term electrical stimulation at frequencies of 5 or 10/sec. It was not prevented by stimulation at frequencies of 20 or 40/sec.

2. Long‐term electrical stimulation of fast rabbit and cat muscles at a frequency of 10/sec had a slowing effect on the time course of contraction and relaxation.

3. It is concluded that the almost continuous low frequency discharge of motoneurones innervating postural muscles plays an important part in establishing and maintaining the slow time course of contraction of these muscles. The characteristically different speeds of contraction of fast and slow striated muscles can in this way be related to the different patterns of impulse activity which they normally receive.
Contractile repriming in snake twitch muscle fibres
Authors: Heistracher P. , Hunt C. C.
Published: December 2014

1. Contractile repriming has been studied in voltage‐clamped snake twitch muscle fibres. Maintained depolarization causes a contractile response which inactivates after a few seconds. Repolarization of the fibre can restore its ability to contract to a subsequent depolarization. This restoration, or repriming, depends on the magnitude and the duration of the repolarization. At −100 mV the minimal period of repolarization which restores contractile response is 0·38 sec. The time for recovery to half maximal tension is about 0·68 sec, and restoration is complete at about 4 sec.

2. Repolarization to smaller levels of membrane potential results in a slower rate of repriming. For example, at −60 mV the mean minimal time for repriming was 2·89 sec, and nearly 17 sec of repolarization was required for full restoration of contractile response.

3. The rate of repriming was not influenced by lowering the external sodium concentration.

4. Repriming could be produced by repetitive, brief pulses of repolarization.

5. The restoration of contractile response and of outward inactivating current showed similar time courses.
The effects of changes in haematocrit on the intrarenal distribution of blood flow in the dog's kidney
Authors: Nashat F. S. , Scholefield F. R. , Tappin J. W. , Wilcox C. S.
Published: December 2014

1. The effect of changes in the haematocrit of blood perfusing the kidney on its intrarenal distribution was studied in dogs.

2. Two types of preparations were employed. (i) In the isolated perfused kidney evidence is presented that flow in the autoregulating preparation represents predominantly cortical flow while flow in the ‘low flow non‐autoregulating’ kidney reflects medullary flow. (ii) In the intact kidney renal blood flow rate and its intrarenal distribution was studied by the injection of 133Xe into the renal artery and measuring its clearance from the kidney by an external counter.

3. In both types of preparation cortical flow was found to be independent of changes in P.C.V. but medullary flow varied inversely with haematocrit.

4. A change in the haematocrit of the perfusing blood leads to alteration of its viscosity. It was argued that an increase in viscosity must lead to a reduction in the resistance of the cortical afferent arterioles but that medullary afferent arterioles were not able to respond in this manner.

5. These findings demonstrate that changes in total body haematocrit cause a redistribution of blood flow between renal cortex and medulla.
Frequencygrams of rabbit spindle primary endings elicited by stimulation of fusi‐motor fibres
Authors: Emonet-Dénand Françoise , Laporte Y.
Published: December 2014

1. Frequencygrams of rabbit spindle primary endings elicited by stimulation of single fusimotor axons were obtained by the method described by Bessou, Laporte & Pagès (1968a) which gives indirect information on the contraction of intrafusal muscle fibres.

2. Repetitive stimulation of the majority of static axons (twenty out of twenty‐five axons studied) gave frequencygrams showing discrete large peaks corresponding to each stimulus, even for rates of stimulation as high as 300‐500/sec.

3. Large responses to single stimuli were elicited by thirteen of these axons. The responses consisted of a fast‐rising phase lasting 5‐10 msec and declining phase lasting 30–50 msec.

4. Repetitive stimulation of some static axons (five out of twenty‐five) gave frequencygrams displaying a smooth contour with no sign of individual responses to single stimuli and with a slow rising and declining phase.

5. Both kinds of ‘static’ frequencygrams may be obtained from the same spindle.

6. Repetitive stimulation of dynamic axons gave frequencygrams of small amplitude with a slow rising and declining phase and no sign of individual responses, even at low rates of stimulation.

7. Although rabbit spindles lack nuclear chain muscle fibres (Barker & Hunt, 1964), rabbit's frequencygrams were essentially similar to those of cat spindles. The functional implications of this similarity are discussed.