bluuebunny/crossref_metadata_2025_split huggingface dataset:
A movement receptor of the small intestine
Authors: Bessou P. , Perl E. R. 
Published: December 2014

1. The characteristics of a mechanoreceptor of the small intestinal region of the cat were studied by recording potentials from single afferent fibres in filaments dissected from mesenteric nerves. Forty‐six fibres were examined in detail. Each of these was excited by light mechanical stimulation of the mesentery or small bowel, but none responded to sinusoidal vibration at frequencies above 100/sec. A ‘spontaneous’ discharge was regularly observed and it appeared to be related to peristaltic intestinal activity. On the other hand, non‐propulsive motor contractions of the intestinal musculature were poorly correlated with discharge frequency.2. The region of maximal sensitivity of each fibre was determined by light pressure applied with a fine probe. Under these conditions the receptive field always resolved itself into 1‐5 sensitive points (smaller than 1 mm in diameter). Each such point lay upon or immediately adjacent to a branch of the mesenteric artery supplying the area. Commonly, one or more sensitive spots were located at the place where a mesenteric artery entered the intestinal musculature. Localized pressure to one sensitive spot evoked a low frequency discharge (under 30/sec) which adapted within several seconds. A movement of the mesentery or the intestine distorting the region near one of the sensitive points regularly evoked a near maximal response. The dynamic phase of distension of the intestine by an intraluminal ballon also evoked a response. During inflation or deflation of the intestinal balloon, the frequency of discharge was positively correlated with both the rate of inflation and the pressure reached at the end of the dynamic phase. There was little relation between static distension and the discharge frequency.3. The conduction velocity of each afferent fibre was determined by electrical stimulation of its mesenteric nerve. The majority of the fibres studied had conduction velocities between 5 and 10 m/sec, the range being 2‐21 m/sec. These figures were taken to indicate that the fibres were myelinated and of small diameter. Histological determination of myelinated fibre diameter in the mesenteric nerves from which the recordings were taken suggested that the numerical factor relating fibre diameter in μ to conduction velocity in m/sec was under 6.4. It was concluded that these receptors signalled movement of the intestine, regardless of its origin.
The presence of ergothioneine in the central nervous system and its probable identity with the cerebellar factor
Authors: Crossland J. , Mitchell J. F. , Woodruff G. N. 
Published: December 2014

1. Ergothioneine has been detected and quantitatively estimated in the brains of mice, rats, guinea‐pigs, rabbits, cats and sheep. It is present in the cerebellum in amounts ranging from about 3·0 μg/g in the cat to 10 μg/g in the guinea‐pig. Amounts in the cerebral hemispheres are much smaller, ranging from < 0·1 μg/g in the cat to 1·6 μg/g in the guinea‐pig.2. Large amounts of ergothioneine (about 30 μg/g) were found in the optic nerves of the rabbit. None was detected in the dorsal columns of the spinal cord of the same species.3. Ergothioneine has an excitatory action on the electrical activity of the cerebellum of the decerebrate rabbit and the excitatory actions of cerebellar extracts on this preparation are completely accounted for by their contained ergothioneine.4. It is concluded that the cerebellar factor of Crossland & Mitchell (1956) is identical with ergothioneine.
The inhibitory innervation of the taenia of the guinea‐pig caecum
Authors: Burnstock G. , Campbell G. , Rand M. J. 
Published: December 2014

1. The inhibitory innervation of the taenia of the guinea‐pig caecum has been studied, after blocking the responses to stimulation of excitatory cholinergic nerves with atropine.2. Stimulation of the perivascular nerves supplying the taenia caused relaxations. These nerves had properties which were typical of sympathetic post‐ganglionic adrenergic nerves. The relaxations caused by stimulation were maximal at frequencies of stimulation above 30 pulses/sec and they were abolished by bretylium, guanethidine and 1,1‐dimethyl‐4‐phenylpiperazinium iodide (DMPP).3. The taenia is also innervated by intramural inhibitory nerves with their cell bodies in Auerbach's plexus. These nerves can be excited by electrical stimulation of the taenia or by the application of ganglion‐stimulating drugs.4. The intramural inhibitory nerves have different properties from sympathetic adrenergic nerves. Relaxations in response to stimulation were maximal with frequencies of stimulation of about 5 pulses/sec and they were not blocked by bretylium, guanethidine or DMPP.5. Preganglionic cholinergic fibres in the caecal wall make synaptic connexions with the intramural inhibitory neurones.6. The role of the intramural inhibitory neurones in intestinal activity and their possible connexions with the central nervous system have been discussed.
Influence of temperature acclimatization on sodium—glucose interactions in the goldfish intestine
Authors: Smith M. W. 
Published: December 2014

1. Transmural potentials across goldfish intestines in vitro were found to depend on the acclimatization temperature of the fish. At any incubation temperature potentials were lower in fish kept previously at a high temperature, and if the transmural potentials were recorded at incubation temperatures equal to the previous acclimatization temperatures the values remained constant from 8 to 30° C. The glucose‐evoked potential was also reduced by previous acclimatization of the fish to a high temperature.2. As the sodium concentration was reduced the steady transmural potential increased and later fell in proportion to the low external sodium concentration, but the glucose‐evoked potential fell as soon as the sodium concentration was reduced below 140 m
M. Similar changes were seen with intestines taken from fish acclimatized to a high temperature but both the steady‐state potential and the transitory glucose‐evoked potential were more dependent on the external sodium concentration.3. The maximum glucose‐evoked potential depended on the concentration of glucose used and temperature acclimatization had no significant effect on this relation. The steady potential was lower in the presence of glucose at low incubation temperatures but higher at higher incubation temperatures, and the temperature at which glucose ceased to inhibit depended on the previous acclimatization temperature. Glucose also lowered the steady potential, whatever the previous acclimatization temperature, when the external sodium concentration was low.4. The inhibitory effect of glucose on the steady potential of an intestine taken from a 30°‐acclimatized fish could be abolished by lowering the external concentration of glucose from 27 to 16 m
M.5. Intestines taken from fish acclimatized to 3° C gave variable results.6. It is concluded that sodium moves across the luminal membrane of the goldfish mucosa attached to a carrier which can exist in one of two forms. It is changes in this postulated carrier which serve to stabilize sodium transport at different acclimatization temperatures. Changes in the concentration of this postulated carrier may also occur and function in the regulation of sodium transport, particularly at acclimatization temperatures below 15° C, where the switching of the carrier does not operate.
A study of the interaction between motoneurones in the frog spinal cord
Authors: Grinnell A. D. 
Published: December 2014

1. A short‐latency interaction between motoneurones has been studied with intracellular and root potential recordings from the isolated spinal cord of the frog. Antidromic stimulation of one ventral root causes brief depolarization (VR‐EPSP) of the motoneurones of adjacent, non‐excited motoneurones. The summed activity of many such VR‐EPSPs can be seen as a brief depolarization (VR‐VRP) passing out an adjacent ventral root.2. Both intracellular and root‐recorded signs of this interaction are graded in amplitude.3. It was found that this interaction decreased with increasing temperature. This is in contrast to the behaviour of the ventral root potential resulting from dorsal root stimulation (DR‐VRP) or the dorsal root potentials resulting from either dorsal root (DR‐DRP) or ventral root (VR‐DRP) stimulation, all of which increased in amplitude from below 10 to about 17° C.4. Pharmacological evidence suggests that the interaction between motoneurones is not chemically mediated. The VR‐VRP was not affected by a large variety of transmitter blocking agents, including curare, dihydro‐β‐erythroidine, atropine, succinylcholine, hexamethonium and DOPA, while the VR‐DRP, which probably originates with the release of ACh from an axon collateral, was consistently blocked.5. Mg2+ suppressed the VR‐VRP more slowly than the other potentials, and this suppression was increased by adding Ca2+, rather than reversed, as in the case of the other root potentials, which are presumably mediated by chemical transmission.6. The interaction between motoneurones is strongly facilitated by orthodromic depolarization of the motoneurones being antidromically stimulated. Extracellular recordings within the cord support the conclusion that this facilitation is a result of the enhancement of antidromic invasion, perhaps especially of the dendrites, by slight depolarization.7. One VR‐VRP (or VR‐EPSP) first suppresses response to another (for about 10 msec), then facilitates response to the second, with maximum effect around 20‐40 msec. This is the case whether both stimuli go to the same or to different ventral roots, although occlusion is less and facilitation greater in the latter case. Occlusion of the VR‐EPSP also results from full excitation of the cell in which recording is being done.8. The mechanism of this interaction remains uncertain, but it would seem likely that overlapping dendrites of adjacent motoneurones interact with each other electrically through close apposition or specialized contacts. Occlusion would result from the refractoriness of strongly depolarized dendrites, facilitation from the enhancement of invasion of antidromically stimulated motoneurones by the weaker (or residual) depolarization occurring after earlier activity of motoneurones or their dendrites.
The effect of acute haemorrhage in the dog and man on plasma‐renin concentration
Authors: Brown J. J. , Davies D. L. , Lever A. F. , Robertson J. I. S. , Verniory A. 
Published: December 2014

1. The effect of acute haemorrhage on the plasma renin concentration was studied in the dog and man.2. Plasma‐renin concentration was regularly increased after the larger bleeds; after the smaller haemorrhages plasma‐renin concentration remained unchanged.3. The results are discussed in relation to current hypotheses concerning the control of renin and aldosterone secretion.
Somatic sensory cortical projection areas excited by tactile stimulation of the cat: a triple representation
Authors: Darian-Smith I. , Isbister J. , Mok H. , Yokota T. 
Published: December 2014

1. The specific somatic sensory projection from the face to the cerebral cortex of the cat was investigated in two series of experiments. α‐chloralose and Nembutal were the anaesthetics used.2. Evoked potentials, recorded at the cortical surface, were used in the first series for identifying three discrete projection areas from the face and forelimb. Two of these regions correspond to the established S I and S II projections. The third area, designated S III, was in the dorsal part of the anterior suprasylvian gyrus adjacent to the ansate sulcus.3. Single neurone analysis demonstrated that the cell populations responding to ‘tactile’ cutaneous stimulation of the face within each of the three specific somatic sensory projection areas had similar static functional properties. Most neurones observed had receptive fields restricted in size and were modality specific. Their receptive fields were mainly contralateral, although some had an ipsilateral extension. Fewer than 10% of cells observed in each specific cortical area were ‘non‐specific’. Such cells had extensive receptive fields and some of these fired to an auditory stimulus.4. Both field recording and single neurone analysis revealed a somatotopic projection to the S III area as well as to the S I and S II areas.
The behaviour of a mammalian muscle during sinusoidal stretching
Authors: Rack P. M. H. 
Published: December 2014

1. Tension changes have been recorded in tetanized and passive cat soleus muscles during sinusoidal stretching at frequencies between 0·25 and 12·5 c/s.2. During sinusoidal stretching the muscle tension varied in an approximately sinusoidal manner. The tension record showed an angular advance on muscle length. A method of measuring mean angular advance in nonlinear systems is described.3. In tetanized muscle, resistance to lengthening increased with increasing frequency of stretching. With increasing frequency the elastic stiffness increased more rapidly than the viscous stiffness, so that at the higher frequencies the angular separation between length and tension became smaller.4. With increasing stretch amplitude the elastic stiffness of the tetanized muscle declined, and the mean angular advance of tension became larger.5. In passive muscle the viscous stiffness increased at the higher frequencies, and the mean angular advance of tension on length was correspondingly increased.6. The functional significance of these findings and their relation to the findings of other workers are discussed.
The effect of membrane fixed charges on diffusion potentials and streaming potentials
Authors: Diamond Jared M. , Harrison S. C. 
Published: December 2014

1. Electrical potential differences (p.d.'s) have been measured across an in vitro preparation of rabbit gall‐bladder.2. When the gall‐bladder separates identical bathing solutions, the p.d. is always zero, regardless of the composition of the bathing solution. Hence the gall‐bladder is symmetrical: i.e. the mucosal and serosal cell membranes have the same relative permeability coefficients.3. Osmotic water flow causes streaming potentials of up to 20 mV, of a sign indicating greater permeability to cations than to anions.4. At constant osmolarity, streaming potentials increase slightly with NaCl concentration. Streaming potentials decrease considerably with changes in osmolarity resulting from changes in NaCl concentration.5. Diffusion potentials resulting from electrolyte concentration gradients are fitted well by the constant‐field equation with the relative permeability coefficients PNa = 1·00, PCl = 0·33, PK = 2·3. These permeability coefficients are independent of osmolarity and of salt concentration.6. Relative to 0·25 m
M‐Ca, 5 m
M‐Ca reduces streaming potentials by 40%, NaCl diffusion potentials by 62%, and potassium diffusion potentials by 43%.7. The aqueous channels through which water and electrolytes traverse the cell membranes of the gall‐bladder contain negative fixed charges, which are blocked by Ca. The physiological significance of the charges may be to reduce chloride permeability and thereby to increase the effectiveness of the gall‐bladder in concentrating bile.8. The effect of pH, and analogy with surface charges of other cells, suggest that the charges are organic acids of low pKa.
Non‐linear osmosis
Authors: Diamond Jared M. 
Published: December 2014

1. The relation between osmotic gradient and rate of osmotic water flow has been measured in rabbit gall‐bladder by a gravimetric procedure and by a rapid method based on streaming potentials. Streaming potentials were directly proportional to gravimetrically measured water fluxes.2. As in many other tissues, water flow was found to vary with gradient in a markedly non‐linear fashion. There was no consistent relation between the water permeability and either the direction or the rate of water flow.3. Water flow in response to a given gradient decreased at higher osmolarities. The resistance to water flow increased linearly with osmolarity over the range 186‐825 m‐os
M.4. The resistance to water flow was the same when the gall‐bladder separated any two bathing solutions with the same average osmolarity, regardless of the magnitude of the gradient. In other words, the rate of water flow is given by the expression (Om — Os)/[Ro′ + ½k′ (Om + Os)], where Ro′ and k′ are constants and Om and Os are the bathing solution osmolarities.5. Of the theories advanced to explain non‐linear osmosis in other tissues, flow‐induced membrane deformations, unstirred layers, asymmetrical series‐membrane effects, and non‐osmotic effects of solutes could not explain the results. However, experimental measurements of water permeability as a function of osmolarity permitted quantitative reconstruction of the observed water flow—osmotic gradient curves. Hence non‐linear osmosis in rabbit gall‐bladder is due to a decrease in water permeability with increasing osmolarity.6. The results suggest that aqueous channels in the cell membrane behave as osmometers, shrinking in concentrated solutions of impermeant molecules and thereby increasing membrane resistance to water flow. A mathematical formulation of such a membrane structure is offered.
Increased permeability of the capillaries of the rat heart to the plasma albumin with asphyxiation and with perfusion
Authors: Sutherland T. M. , Young D. A. B. 
Published: December 2014

1. Studies on the rate of efflux from the isolated perfused rat heart of plasma albumin conjugated with Evans Blue showed the conjugate to have penetrated extensively the extravascular compartment of the organ during a period of 2 min. This was confirmed by direct analysis of hearts for Evans Blue after perfusion.2. Exposure of the hearts to Evans Blue‐albumin conjugate for 8 min in vivo showed no significant penetration of the interstitial space.3. With the isolated preparation inclusion of promethazine in the perfusing medium significantly diminished the rate of penetration of the extravascular compartment by the conjugate as did injection of the animals with either reserpine 2 days before, or bretylium immediately before the experiment.4. Penetration of the interstitial compartment in vivo could be induced by repeated asphyxiation. This penetration could also be diminished by promethazine but was not influenced by mepyramine maleate.The increased permeability of capillaries to plasma proteins can be readily demonstrated in the whole animal by detecting the leakage from the vasculature of the plasma proteins conjugated with a dye (Menkin & Menkin, 1930; Miles & Miles, 1952). Evans Blue, which has been widely used as a vascular marker because of the stability of its conjugate with plasma albumin, is the most suitable dye for this purpose. In the present work this method has been applied to the isolated rat heart, to determine if changes in capillary permeability occur in the perfused tissue.When plasma albumin conjugated with Evans Blue was used as a vascular marker in this preparation, its rate of clearance was very much less than that of erythrocytes, and the amount contained in the heart corresponded to a space approaching that occupied by extracellular markers such as raffinose and inulin. It was concluded, therefore, that there was a failure of a considerable number of the cardiac capillaries to retain the plasma albumin, and subsequent work was directed towards the identification of the condition that gives rise to these changes and the possible involvement of a permeability factor.A preliminary account of part of this work was given to the Physiologcal Society (Sutherland & Young, 1961).
Taste reception in the goat, sheep and calf
Authors: Bell F. R. , Kitchell R. L. 
Published: December 2014

1. The goat, sheep and calf have gustatory chemoreceptors which respond to salt, sweet, sour and bitter solutions, from which the afferent fibres pass centrally in the chorda tympani and glossopharyngeal nerves.2. Action potentials in the afferent gustatory nerves can also be detected when the tongue is irrigated with sodium bicarbonate, ethylene glycol, glycerine, and saccharine.3. Distilled water reduces the background activity in the isolated gustatory nerves, thus demonstrating the absence of fibres in ruminant ungulates of receptors which respond to stimulation by distilled water.4. The responses from the chemoreceptors, associated especially with the circumvallate papillae, are enhanced if the papillae are gently moved at the time of irrigation with sapid solutions.5. The chorda tympani is most responsive to salt and acid solutions while the glossopharyngeal is more responsive to sugars, quinine and acid.
The formation of peptides with uterine activity from ovine, human and bovine growth hormones and from bovine and ovine lactogenic hormones
Authors: Lockett Mary F. 
Published: December 2014

1. Both starch gel and disk electrophoresis demonstrated stepwise degradation of acidic preparations of human and bovine growth hormones and of ovine and bovine lactogenic hormones in solution at pH 9·0‐10·0. This developed in 1‐3 weeks in refrigerated solutions and in 5‐16 hr on incubation at 37° C. Increasing acidity accompanied degradation.2. Oxytocic activity, initially absent, developed in these same solutions of hormones during stepwise degradation and appeared to be associated with a single phase of degradation.3. Storage in solution at pH 9·5 generated oxytocic activity in an initially basic preparation of ovine growth hormone. The uterine action was attributable to a small amount of acidic material with electrophoretic properties very similar to those of the oxytocic fractions formed during stepwise degradation of the acidic preparations of growth and lactogenic hormones.4. Prolonged storage of all these hormones at pH 9·0‐10·0 resulted in the formation of acidic substances of low molecular weight which ran close to the buffer front and were dialysable (14 hr) through membranes which permitted the passage of nonapeptides in 6‐8 hr.5. α‐Chymotrypsin very rapidly generated uterine stimulant action in freshly prepared solutions of human growth and bovine lactogenic hormones at pH 9·5.6. All the hormone samples used proved capable of hydrolysing purified ox haemoglobin, urea‐denatured, at pH 9·5.
Rapid hydrogen ion uptake of rod outer segments and rhodopsin solutions on illumination
Authors: Falk G. , Fatt P. 
Published: December 2014

1. Flash illumination of a suspension of frog rod outer segments or rhodopsin solution in contact with a platinum electrode produces a rapidly developing negative displacement of potential of the electrode (with respect to a reversible electrode).2. The amplitude of the potential change varies inversely with the H+ buffering capacity of the medium. It is inferred that the response is due to an uptake of H+ by the rod outer segments or rhodopsin, with the platinum surface acting as a pH electrode.3. Determination of the action spectrum shows that the response depends on the absorption of light by rhodopsin.4. In frog rods one acid‐binding group with a pK of about 7·9 is produced for each molecule of rhodopsin bleached, consistent with a rhodopsin concentration in frog rods of 1·7 m
M.5. It is suggested that the time course of the response with rhodopsin solutions reflects the kinetics of the conversion of metarhodopsin I to metarhodopsin II.6. A slower time course of voltage change observed for suspensions of outer segments is attributable to the time required for the diffusion of H+ buffer out of the rods.