bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of lowering external sodium on the intracellular sodium activity of crab muscle fibres.
Authors: Vaughan-Jones R D
Published: December 2014

1. Intracellular Na activity, aiNa, was continuously measured in crab (Carcinus maenas) muscle fibres using a recessed‐tip Na+ ‐sensitive glass micro‐electrode. Experiments could last up to several hours. AiNa remained stable during prolonged experiments. The mean resting aiNa was 8‐4 +/‐ 0‐02 mM (S.E. of mean for eighty‐nine fibres) and the mean resting membrane potential was 65‐3 mV +/‐ 0‐3 (S.E. of mean for eighty‐nine fibres). 2. Reducing [Na]o to 1/10 normal (maintaining ionic strength with equivalent amounts of either Li or Tris) caused a large and rapid fall of aiNa. There appeared to be two components of the effect, a fast and slow. The initial fast rate of decrease was about 3‐5 m‐mole/min decreasing to half this value in about 1 min. The rate of decrease of aiNa was not linearly related to aiNa. The size of the fast change of aiNa was related to the magnitude of the Na gradient across the membrane. 3. High concentrations (2 x 10‐4m) of ouabain caused a very slow rise of aiNa by 1 or 2 mn/hr. This was equivalent to a net Na influx of between 1 and 10 p‐mole/cmi. sec, depending on whether or not a correction was applied to account for the increased surface area of the fibre caused by the invaginating cleft system. 4. The response to low Nso was virtually insensitive to the removal of Ko or to prolonged reatment with high concentrations of ouabain (2 x 10‐4 m; 100 min) and so could not readily be attributed to active Na/K pumping. 5. The response of aiNa to low Nao was reversibly inhibited by high concencentrations of Mn (50 mm) and by low concentrations of La (3‐1 mm). La itself stimulated a rapid fall of aiNa in normal Nao.
Dual effects of hemicholinium‐3 at central cholinergic synapses.
Authors: Craig C R , Curtis D R , Lodge D
Published: December 2014

1. Hemicholinium‐3 (HC‐3) has at least two presynaptic effects at cholinergic synapses between motor acon collaterals and spinal Renshaw cells, neither of which influenced non‐cholinergic excitatory synapses on dorsal horn interneurones. 2. One, which occurred independently of repetitive activity of the synapses and which resulted in increased latency of synaptic excitation, presumably involved changes in the properties of presynaptic fibres and terminals which influenced transmitter release. 3. The other, which depended on continuous repetitive synaptic activity, was consistent with depletion by HC‐3 of presynaptic stores of acetylcholine (ACh).
The alteration by ouabain of calcium movements in human red cell ghosts.
Authors: Isern M , Romero P J
Published: December 2014

1. The influence of ouabain on net Ca movements was studied in human erythrocyte ghosts by atomic absorption spectrophotometry. 2. Ouabain (10(‐5) M) showed a dual effect, altering both entry and exit of Ca from K‐rich ghosts incubated in a high‐Na medium in the presence of 10 mM‐Ca. 3. Stimulation of Ca entry was observed in the first 15 min at 37 degrees C, whereas during the subsequent 15 min incubation ouabain elicited Ca extrusion. This latter effect was eliminated when the ouabain concentration was raised to 1 mM. 4. Ouabain‐dependent Ca movements were abolished by replacing both internal K and external Na with choline. They were also absent from ghosts prepared at a high lytic ratio (1 : 100) or obtained from ATP‐depleted cells. 5. A moderate increase in cell ATP enhanced the effect of ouabain on Ca efflux whilst it was eliminated at higher ATP levels. 6. The actions of ouabain markedly depended on the initial ADP/ATP ratio in ghosts, being optimal at about 2‐5. 7. The results suggest that the effects of ouabain on Ca movements are mediated through the Na pump. Reversal of this pump in Na‐rich K‐free medium may provide the energy for active Ca transport.
The effect of preganglionic nerve stimulation on the accumulation of certain analogues of choline by a sympathetic ganglion.
Authors: Collier B , Ilson D
Published: December 2014

1. Cat superior cervical ganglia were perfused with a Krebs solution containing 10(‐6) M [3H]homocholine (2‐hydroxypropyl‐trimethylammonium) or 10(‐5) M [14C]triethylcholine (2‐hydroxyethyl‐triethylammonium). Preganglionic nerve stimulation (20 Hz) increased the accumulation of homocholine (3‐2‐fold) and of triethylcholine (2‐1‐fold). This increased accumulation during stimulation was not the result of increased metabolism. 2. The increased accumulation of homocholine or triethylcholine induced by pregnaglionic nerve stimulation was not reduced by tubocurarine or by atropine, but it was blocked by choline and by hemicholinium. These results suggested that preganglionic nerve stimulation increased choline analogue accumulation into cholinergic nerve terminals. 3. The increased accumulation of homocholine or of triethylcholine induced by preganglionic nerve stimulation was reduced when the Ca2+ concentration was reduced and was abolished in the absence of Ca2+. However, changes in the Mg2+ concentration which depressed acetylcholine (ACh) release by amounts comparable to those induced by altered Ca2+ concentrations did not alter the uptake of homocholine or triethylcholine. It is concluded that the uptake of choline analogues is not regulated by transmitter release but that stimulation increases the uptake of the choline analogues by a Ca2+‐dependent mechanism. 4. The accumulation of ACh by ganglia perfused with a Krebs solution containing choline and high MgSO4 (18 mM) was measured. The ACh content of these ganglia did not increase, although choline transport presumably exceeded that necessary for ACh synthesis to replace released ACh. It is concluded that choline transport does not limit ACh synthesis in ganglia.
Interaction of air temperature and core temperatures in thermoregulation of the goat.
Authors: Jessen C
Published: December 2014

1. The interaction between air temperature, hypothalamus temperature, and spinal cord temperature in driving heat production and respiratory evaporative heat loss has been studied in conscious goats with chronically implanted thermodes. 2. Thermoregulatory heat production could be described as being approximately proportional to the sum of two linear drives determined by hypothalamus temperature and spinal cord temperature. This was found also for respiratory evaporative heat loss except that it was not influenced by spinal cord cooling. 3. Thermoregulatory heat production could be further described as being approximately proportional to a product of linear drives determined by hypothalamus and spinal cord temperature on one hand and air temperature on the other. Respiratory evaporative heat loss was approximately proportional to the sum of drives determined by spinal cord, hypothalamus and air temperatures. 4. Sensitivity to central cooling was found to undergo long‐lasting but temporary changes which interfered with the immediate effects of air temperature on thermoregulation. 5. Central threshold temperatures for heat production and respiratory evaporative heat loss were found to be differently affected by air temperature. This indicates that integrating mechanisms for heat production and respiratory evaporative heat loss are to some extent functionally independent.
Innervation of the rabbit rectococcygeus muscle and the functional relationship of the muscle to the terminal large intestine.
Authors: King B F , McKirdy H C , Wai S S
Published: December 2014

1. The rectococcygeus muscle is supplied by cholinergic motor fibres from the parasympathetic division of the autonomic nervous system. 2. The histofluorescence technique reveals a sparse adrenergic innervation. 3. When a maintained state of partial contraction is induced by carbachol, stimulation of the extrinsic sympathetic nerves produces a relaxation of the muscle which is usually followed by contraction. 4. The rectococcygeus muscle may also receive nerves which are neither adrenergic nor cholinergic. 5. Ganglion cells have been found close to and, in some preparations, within the muscle; the role of these ganglion cells is not clear. 6. It would appear that the rectococcygeus muscle and the longitudinal muscle of the rectum are not linked by a myogenic mechanism. The rectococcygeus muscle would, however, appear to be linked by nerve fibres to neighbouring structures.
Excitatory responses of neurones in rat bulbar reticular formation to bulbar raphe stimulation and to iontophoretically applied 5‐hydroxytryptamine, and their blockade by LSD 25.
Authors: Briggs I
Published: December 2014

1. The micro‐iontophoretic technique has been used to study the responses of single neurones in the bulbar reticular formation to 5‐hydroxytryptamine and to noradrenaline, ACh or glutamate, and to compare these with the responses to electrical stimulation in or near the bulbar raphe nuclei. 2. In the bulbar reticular formation, most neurones were excited by 5‐hydroxytryptamine; forty‐three of fifty‐one neurones excited by 5‐hydroxytryptamine were also excited by stimulation in nucleus raphe magnus, nucleus raphe pallidus or nucleus raphe obscurus. Most of these stimulation‐induced excitations were of long latency: LSD reduced six of seven of these excitations tested, while 5‐hydroxytryptamine excitations were blocked on all seven. 3. In contrast, stimulation of areas adjacent to the raphe nuclei excited only fifteen of forty‐six neurones excited by 5‐hydroxytryptamine. Most of these stimulation effects were of short latency and none of the three tested were reduced by LSD, although 5‐hydroxytryptamine excitations were blocked. 4. The relationship of the long‐latency excitatory effects of stimulation with the position of the stimulating electrode in the raphe nuclei indicates that these effects are probably mediated via the raphe neurones and this is supported by the correlation of the effects of raphe stimulation with the effects of 5‐hydroxytryptamine applied iontophoretically and by the ability of LSD to block both effects. 5. The results provide a physiological basis for the excitatory effects of iontophoretically applied 5‐hydroxytryptamine in the bulbar reticular formation.
Connexions from large, ipsilateral hind limb muscle and skin afferents to the rostral main cuneate nucleus and to the nucleus X region in the cat.
Authors: Johansson H , Silfvenius H
Published: December 2014

1. Evidence is presented for an input from ipsilateral hind limb group I muscle afferents and low threshold cutaneous afferents, to cells in the rostral division of the main cuneate nucleus (rMCN) and in the region of the descending vestibular nucleus and the nucleus X of Brodal & Pompeiano (1957a), the (DV‐X). 2. Thirteen group I‐rMCN cells were recorded from. The functional properties of these cells were similar to those of nueleus Z (Landgren & Silfvenius, 1971; Johansson & Silfvenius, 1977a, b). The cells were monosynaptically linked to spinal dorsolateral fascicle (DLF) fibres. Nine cells projected to the contralateral thalamus, i.e. a second group I hind limb bulbothalamic tract is described. Ten cells were synaptically activated from the ipsilateral cerebellum from the anterior projection zone of the dorsal spinocerebellar tract (DSCT). Axon‐collateral activation by DSCT fibres was established for two of these cells. They were both bulbothalamic relay cells. For the remaining eight cells, activated from the cerebellum, this was not proven. These cells could, however, either be linked to DSCT fibres or to short axon‐collaterals of a cell body of unknown location. A projection from the rMCN to the cerebellum is described and agrees with recent anatomical findings. Two cells were not excited from the cerebellum. 3. Four rMCN cells were activated by cutaneous afferents with their secondary axons in the DLF. Suggestive evidence for a bulbothalamic cutaneous hind limb path via the rMCN is presented. Two cells were activated from the cerebellum, presumably via axon‐collaterals of nonsegmental cells. 4. Eight group I‐DV‐X cells were recorded from. They were monosynaptically linked to spinal DLF fibres and resembled functionally the nucleus Z and rMCN cells when stimulated from the periphery. Two cells projected to the contralateral thalamus, and two others were synaptically excited. Seven cells were activated from the ipsilateral cerebellum. Two of them projected to the cerebellum, and three were synapitcally activated by axon‐collaterals of an undefined non‐segmental cell. 5. Two DV‐X cells which were activated by cutaneous afferents possibly had their spinal fibres deep in the dorsal column. Both were activated from the cerebellum, one by collaterals of a spinal axon. The functional organization of the three juxtaposed medullary nuclei, Z, rMCN and DV‐X is discussed.
Gonadotrophin secretion in the ovariectomized guinea‐pig: effects of electrical stimulation of the hypothalamus and of LH‐RH.
Authors: Donovan B T , Haar M B , Parvizi N
Published: December 2014

1. Serial blood samples were collected from anaesthetized spayed guinea‐pigs subjected to anterior hypothalamic stimulation or injected with luteinizing hormone‐releasing hormone (LH‐RH), and the effect on the secretion of follicle‐stimulating hormone (FSH) and LH followed. 2. Hypothalamic stimulation enhanced LH secretion, although the response waned during the course of the 1 hr period of stimulation; the secretion of FSH was not increased. After stimulation, FSH and LH levels fell below control values. 3. The response to stimulation of the hypothalamus was greater 2 weeks after spaying than after 1 week. 4. Since repeated periods of hypothalamic stimulation induced repeated surges of LH secretion, the decline in LH secretion during stimulation was not likely to have resulted from hypothalamic damage, while the observation that the plasma concentration of FSH and LH declined below control values after brain stimulation implies the operation of inhibitory mechanisms. 5. Pre‐treatment of spayed guinea‐pigs with progesterone depressed the resting plasma concentration of LH but did not affect the immediate response to hypothalamic stimulation. After hypothalamic stimulation the plasma gonadotrophin levels did not fall below control values. 6. Pre‐treatment with oestradiol benzoate depressed the resting plasma level of LH and slightly reduced the size of the LH surge produced by hypothalamic stimulation. However, the raised plasma LH concentration was sustained after stimulation ended. 7. The response to hypothalamic stimulation after pre‐treatment with progesterone and oestradiol benzoate showed features of the reaction to each steroid given singly. 8. The I.V. injection of 0‐5 microng LH‐RH induced a surge of LH secretions without affecting FSH discharge. 9. Pre‐treatment with progesterone did not greatly modify the response to LH‐RH but after an injection of oestradiol the high level of LH produced by the releasing factor was sustained for about 2 hr. 10. Injections of LH‐RH during the phase of depressed LH release after hypothalamic stimulation produced a surge of LH secretion which matched that seen in non‐stimulated animals.
Trans‐proximal tubular steady‐state concentration differences studied by micro‐puncture and tissue content of sodium and chloride at varying intraluminal sodium concentrations in vitro in rat kidney cortex slices: evidence for a multisite sodium transport system.
Authors: Györy A Z , Roby H
Published: December 2014

1. With the aid of micropuncture techniques, proximal tubular transepithelial concentration differences for Na (deltaC Na) and chloride (deltaC Cl) were measured in kidney cortex slices at bathing fluid Na concentrations from 10 to 400 m‐mole. kg‐1. Tissue content of water, Na and K was also measured in such slices. Under steady‐state conditions of zero net flux of NaCl and water, deltaC Na represents the sum of active Na transport, factored by the tubular permeability coefficient added to a component of flux due to electrical forces. 2. The relation between bathing fluid Na concentraton and deltaC Na appeared sigmoid in form suggesting an allosteric mechanism for the transport step. 3. Transtubular potential difference, calculated from transepithelial Cl distribution ratios, did not appear constant at the various bathing fluid Na concentrations. Correcting for the effect of these potential differences on the value of each deltaC Na did not convert the sigmoid transport curve to a hyperbolic one, confirming the suggested allosteric nature of the active Na transport step. 4. Intracellular Na content varied linearly with bathing fluid Na concentrations implying free entry of this cation into the cell. This also suggests that the sigmoid transport curve is related to the properties of the active Na transport pump.
Background adaptation in the rods of the frog's retina.
Authors: Hemilä S
Published: December 2014

1. Aspartate‐isolated photoresponses of the red rods to flashes and steps of light have been recorded, both in the presence of and without background lights of varying strength. 2. The results are interpreted in terms of a model of rod outer segment adaptation, where the three model parameters correspond to the adaptation processes associated with the transmitter release, the transmitter background concentration and the plasma membrane leakage, respectively. 3. The stimulus‐response function deviated somewhat from the Michaelis equation U/Umax=I/(I + IH). During light‐adaptation the operating curve, the stimulus‐response function plotted in a log‐log diagram, retained approximately its shape while moving strongly to the right along the log intensity axis and to a lesser degree downwards (Umax‐decrease). 4. The movement of the operating curve was such that the rods approximately obeyed Weber's law. In the cases of flash and step of light stimuli the movement of the operating curve was about the same. 5. When a moderate background light was turned on a large decrease of sensitivity was first observed. During a period 0‐5‐1 min the sensitivity increased towards the stationary value. After extinguishing the background light the dark sensitivity returned in 0‐5‐1 min and then a period of hypersensitivity lasting typically 1 min was observed. 6. The experimental results, as interpreted according to the model, indicate that light‐adaptation decreases q, the number of transmitter molecules released by one bleached rhodopsin molecule. 7. There is probably an adaptation process also in the rod inner segment, which increases the sensitivty of the rod to transient stimuli.
Increase in human intestinal permeability following ingestion of hypertonic solutions.
Authors: Laker M F , Menzies I S
Published: December 2014

1. A simple oral loading technique involving the ingestion of solutions containing lactulose is described. Timed urinary excretion of lactulose, which is non‐metabolizable, is used as an indicator of intestinal permeability, and measured by quantitative paper chromatography. 2. This technique has been used to investigate the intestinal permeability of apparently healthy adults following the ingestion of solutions made hypertonic by the addition of the solutes sucrose, glucose, mannitol, glycerol, urea and sodium chloride. 3. These experiments show that intestinal permeability to lactulose increases as the solute concentration in the ingested solution is increased. Susceptibility to this effect, though consistent for each individual, shows considerable variation between subjects. 4. Factors thought to be pernitent to the enhancement of intestinal permeability by hypertonic solutions, and some possible implications of this, are discussed.
Sodium efflux from voltage clamped squid giant axons.
Authors: Landowne D
Published: December 2014

1. The efflux of radioactive sodium was measured from squid axons during simultaneous voltage clamp experiments such that it was possible to determine the efflux of sodium associated with a measured voltage clamp current. 2. The extra efflux of sodium associated with voltage clamp pulses increased linearly with the magnitude of the depolarization above 40 mV. A 100 mV pulse of sufficient duration to produce all of the sodium current increased the rate constant of efflux by about 10(‐6). 3. Application of 100 nM tetrodotoxin eliminated the sodium current and the extra efflux of radioactive sodium. 4. Cooling the axon increased the extra efflux/voltage clamp pulse slightly with a Q10 of 1/1‐1. On the same axons cooling increased the integral of the sodium current with a Q10 of 1/1‐4. 5. Replacing external sodium with Tris, dextrose or Mg‐mannitol reduced the extra efflux of sodium by about 50%. The inward sodium current was replaced with an outward current as expected. 6. Replacing external sodium with lithium also reduced the extra efflux by about 50% but the currents seen in lithium were slightly larger than those in sodium. 7. The effect of replacing external sodium was not voltage dependent. Cooling reduced the effect so that there was less reduction of efflux on switching to Tris ASW in the cold than in the warm. 8. The extra efflux of sodium into sodium‐free ASW is approximately the same as the integral of the sodium current. Adding external sodium produces a deviation from the independence principle such that there is more exchange of sodium than predicted. Such a deviation from prediction was noted by Hodgkin & Huxley (1952c). 9. Using the equations of Hodgkin & Huxley (1952c) modified to include the deviation from independence reported in this paper and its temperature dependence, one can predict the temperature dependence of the sodium efflux associated with action potentials and obtain much better agreement than is possibly without these phenomena. 10. This deviation from independence in the sodium fluxes is the type expected from some kind of mixing and binding of sodium within the membrane phase.
An analysis of the action of a false transmitter at the neuromuscular junction.
Authors: Colquhoun D , Large W A , Rang H P
Published: December 2014

1. The action of monoethylcholine (MECh) on neuromuscular transmission has been studied by electrophysiological methods. 2. End‐plate potentials (e.p.p.s.) in curarized rat muscle were unaffected or slightly increased in amplitude by MECh (0‐1‐1 mM). Stimulation at 3 Hz for about 30 min in the presence of MECh caused a progressive decline in e.p.p. amplitude, and a shortening of the e.p.p. time course. These changes were reversed by addition of choline to the medium. Similar changes in amplitude, but no change in time course, occurred when the preparation was stimulated in the presence of hemicholinium or triethylcholine. 3. Extracellular recordings of miniature end‐plate potentials in frog muscle showed that stimulation in the presence of MECh caused the time constant of the exponential decay of the m.e.p.p.s. to decrease by 42%. The amplitude of intracellular m.e.p.p.s. was reduced by 45%. These changes were maximal by the time about 3 X 10(5) quanta had been released. 4. Voltage clamp experiments in rat muscle in which miniature end‐plate currents (m.e.p.c.s) were recorded showed that stimulation in the presence of MECh reduced the amplitude (by 33%) and the decay time constant (by 42%). 5. Analysis of end‐plate current flucutations produced by local application of acetylcholine (ACh) and acetylmonoethycholine (AMECh) to voltage clamped rat end‐plates showed that the amplitude of the elementary current events was the same for both compounds whereas the average channel lifetime was 44% shorter for AMECh than for ACh. 6. The voltage‐sensitivity of the channel lifetime (measured from end‐plate current fluctuations) was the same for ACh and AMECh. The voltage‐sensitivity of the m.e.p.c. decay time constant was the same as that found from noise measurements. The shortened m.e.p.c.s. (false m.e.p.c.s.) occurring after stimulation in the presence of MECh also showed the same voltage‐sensitivity. 7. Both normal and false m.e.p.c.s. were prolonged by neostigmine by almost the same factor; false m.e.p.c.s. were thus shorter than normal m.e.p.c.s. even when cholinesterase was inactivated. Experiments with progressive curarization of neostigmine‐treated end‐plates suggested that the fraction of transmitter molecules bound is smaller for false than for normal m.e.p.c.s. The difference implies that the false transmitter has one quarter of the affinity of ACh for the receptors. 8. It is concluded that stimulation in the presence of MECh gives rise to a false transmitter, presumably AMECh, which has a lower affinity for receptors than ACh, and gives rise to ionic channels with a shorter average lifetime than those activated by ACh.
The changes in configuration of the rib cage and abdomen during breathing in the anaesthetized cat.
Authors: Da Silva K M , Sayers B M , Sears T A , Stagg D T
Published: December 2014

1. The external surface of the rib cage and abdominal wall in anaesthetized cats was surgically exposed in order to record their movements cinematographically in spontaneous breathing and in paralysed cats, during artificial positive pressure ventilation. 2. Cine‐stereophotography was used to allow the recording of the movements of a set of markers placed on the external surface of the trunk wall and the corresponding stereometric data were numerically and graphically processed into three‐dimensional drawings. The cine‐film frames corresponding to the phases of maximum inflation and deflation of the lungs were analysed to reveal the changes in configuration associated with the respiratory movements of the trunk wall. 3. The changes in shape of the diaphragm and the diaphragm and the displacements of the abdominal viscera between extreme inflation and deflation were recorded by X‐ray photography. 4. During spontaneous inspiratory movements, the ribs rotated outwards and rostrally about the costovertebral joints, bringing about an increase in the transverse dimensions of the cage all along its length; these movements were accompanied by a clear‐cut caudad displacement of the sternum, caused by the straightening of the costal cartilages and by the widening of the angles defined at sternochondral joints between the sternum and each of the costal cartilages. 5. Neuromuscular blockade abolished muscle tone in the trunk wall, allowing the weight of the viscera markedly to deform its configuration. 6. The inspiratory rib movements of the paralysed animal during artificial inspiration were similar to those during spontaneous breathing but the movements of the sternum were inverted and showed small cranial displacements. 7. The loss of muscular tone under neuromuscular blockade made the abdominal wall more compliant than the rib cage to the positive lung pressure and allowed greater mobility of the viscera with consequent distortion of the shape of the diaphragm. 8. The role of rib cage muscle tone in meeting requirements of purely configurational character in such a shell‐like structure is discussed in relation to the optimal mechanical performance of the diaphragm.
The red and green cone visual pigments of deuternomalous trichromacy.
Authors: Alpern M , Moeller J
Published: December 2014

1. Three "simple" deuteranomalous trichromats match with abnormally low "red" tristimulus values throughout the spectrum and abnormally high "green" tristimulus values in the long wave end of the spectrum which become normal (and then low) in the yellow‐green. The spectrum locus of this transition differs from one anomalous to the other. Differences in the matches of two of these cannot be due to differences in eye media transmissivities alone. Therefore these two deuteranomalous have different cone visual pigments. 2. The analytical anomaloscope was used in the confrontation of one deuteranomalous with six deuteranopes in turn. In each confrontation the deuteranope set the anomaloscope in his mode and adjusted the intensity of the monochromatic light for a match. Deuteranomalous matches were rejected by four of these six deuteranopes. 3. They were accepted by two of the six. These two rejected each other's matches in a way not attributable to differences in eye media transmissivity. 4. Three different psychophysical techniques were used to measure the action spectra of the long wave cones of these two deuternopes. All three methods reveal small but systematic differences in lambdamax and shape of the curve for the one deuteranope compared with that of the other. 5. In red‐green spectral range, these spectra are accurately described by different linear combinations of the color matching functions of the same deuteranomalous whose matches the two deuteranopes accept. Linear combinations of those of a second deuteranomalous, with at least one different kind of cone, fit less well. 6. The wave length discrimination curve of the former deuteranomalous was measured with a new method. The curves of two normals were also obtained for comparison. Wave‐length discrimination predictions from the Stiles (1946) line element theory were compared to the anomalous curve. The deuteranopic action spectra were used in the line element to compute this deuteranomalous' discrimination. There is reasonable first order correspondence between prediction and observation, but the prediction is sensitive to small changes in the derivatives of the logarithms of the action spectra. 7. Line element prediction of the deuteranomalous step‐by‐step luminous efficiency curve is insensitive to such uncertainties. The agreement with expectation from the above assumptions and the measured step‐by‐step deuteranomalous luminous efficiency curve in the red‐green part of the spectrum is therefore good. 8. It is concluded that the erythrolabe in one deuternope's long wave cones has the action spectrum of this deuteranomalous' long and the erythrolabe in the other deuternope's long wave sensitive cones has that of this deuternomalous' medium wave cones. This leads to a general hypothesis about the nature of all forms of red‐green colour vision defects transmitted recessively on the X chromosome.
A‐band length, striation spacing and tension change on stretch of active muscle.
Authors: Hill L
Published: December 2014

1. Single muscle fibres of the frog were stretched during tetanus and filmed down the interference microscope. 2. Sarcomere lengths and A‐ and I‐band widths were measured from cine films taken of the experimental sequences. 3. When a fibre was stretched during a tetanus, its A‐band widths remained constant while its I‐band widths changed according to the extent of the stretch. This behaviour is identical with that of a fibre stretched at rest. 4. Sarcomere lengths remained uniform along the fibre during a tetanus plus stretch, increasing as the I‐band widths increased when the fibre was stretched. 5. At sarcomere lengths longer than LPmax (the length corresponding to greatest isometric tetanus tension) where the isometric tension diminishes as the fibre is lengthened, if the stretch was imposed during a tetanus the tension was higher after the stretch than before, showing a plateau which lasted for the duration of the tetanus. 6. This effect increased with longer sarcomere lengths and was not due to increased resting tension.
Separative pathways for urea and water, and for chloride in chicken erythrocytes.
Authors: Brahm J , Wieth J O
Published: December 2014

1. Urea and water permeabilities of chicken erythrocytes are considerably lower than those of mammalian red cells. 2. The permeabilities to urea, thiourea and to N‐methylurea (about 10(‐6) cm/sec at 25 degrees C) were independent of concentration within a very broad range, and we found no evidence of interaction between transport of analogue molecules. The activation energies were between 17 and 19 kcal/mole, and urea transport was not inhibited by phloretin, which inhibits urea transport in mammalian red cells. 3. The water permeability of chicken red cells (as measured by the diffusion of tritiated water) was 1‐35 X 10(‐3) cm/sec at 25 degrees C. The activation energy was 10 kcal/mole, and the water permeability was not affected by phloretin or parachloromercuribenzoate. 4. It is concluded that the urea and water permeabilities of the chicken erythrocyte membrane are similar to those of a non‐porous bimolecular phospholipid membrane. 5. Like the red cells of other animal species the chicken red cell membrane contains an anion transport system, mediating a rapid exchange of chloride across the cell membranes. The pH dependence, temperature dependence, and sensitivity to inhibitors were similar to the properties of the anion transport system found in mammalian red cells. Our study shows, therefore, that the transport system offers a highly specific pathway to the exchange of anions, without presenting an inspecific leak to the permeation of water and urea.
The distribution of acetylcholine receptors on muscle fibres of regenerating salamander limbs.
Authors: Dennis M J , Ort C A
Published: December 2014

1. Muscle fibres developing during limb regeneration were examined for responsiveness to acetylcholine (ACh) applied iontophoretically along the membrane. 2. Fibres which were uninnervated as well as those with non‐transmitting synapses had high over‐all sensitivities, with only minor variations along their length. 3. Functionally innervated fibres in which depolarization did not yet elicit action potentials had high over‐all sensitivities, even when the synaptic potentials ahd amplitudes of 40‐50 mV. In these the membrane in the vicinity of synapses tended to have sensitivities above the background level. 4. Upon the appearance of action potentials, several weeks after fibre innervation, the responsiveness to ACh began to decline in synapse free regions of the membrane. In mature muscle the sensitivity to ACh is restricted to sites of synaptic contact.
The effects of somatostatin and metiamide on tachyphylaxis of pentagastrin stimulated gastric acid and pepsin secretion in the conscious cat.
Authors: Albinus M , Blair E L , Hirst B H , Reed J D , Schally A V , Shaw B
Published: December 2014

1. Pentagastrin stimulated gastric acid and pepsin secretions show parallel rates of tachyphylaxis in the conscious cat. The responses to histamine show only slight tachyphylaxis. 2. Somatostatin 10 microng.kg(‐1).hr(‐1) inhibits pentagastrin but not histamine stimulated acid secretion and inhibits pentagastrin stimulated pepsin secretion. 3. The inhibition of pentagastrin stimulated acid and pepsin secretion by Somatostatin delays the tachyphylaxis of these responses, but the rates of tachyphylaxis when they do subsequently occur are identical. 4. Metiamide 10 mg‐kg(‐1)‐hr(‐1) equally inhibits histamine and pentagastrin stimulated acid secretion but does not inhibit pentagastrin stimulated pepsin secretion. 5. Inhibiton of acid secretion during metiamide infusion neither prevents nor delays acid nor pepsin tachyphylaxis. 6. It is suggested that tachyphylaxis of acid and pepsin secretion is a gastrin receptor phenomenon and that Somatostatin occupies or modifies the behaviour of these receptors, preventing tachyphylaxis. Metiamide, however, exerts its action only on the histmine H2‐receptor and not the gastrin receptor mechanism, and this apparently does not prevent or delay acid tachyphylaxis.
Effects of replacing medium sodium by choline, caesium, or rubidium, on water and ion contents of renal cortical slices
Authors: Hughes Pauline M. , Macknight Anthony D. C.
Published: December 2014

1. Renal cortical slices from rat, rabbit, and guinea‐pig were incubated in media in which choline, caesium or rubidium replaced sodium.

2. Slices of rabbit and guinea‐pig renal cortex incubated in oxygenated choline Ringer decreased in volume initially and did not swell over 3 hr at 25° C. There was a steady loss of potassium. Inhibition of metabolism (N2 + 1 m
M iodoacetamide) caused some swelling. Ouabain, 10 m
M, in choline Ringer affected neither loss of potassium nor tissue water content.

3. Slices of rat renal cortex similarly incubated in choline Ringer swelled over 3 hr at 25° C whether or not metabolism was inhibited; ouabain (15 m
M) affected neither tissue potassium loss nor tissue water content.

4. Incubation in choline Ringer containing either 0·2 m
M p‐chloromercuribenzoic acid, or 1 m
M ethacrynic acid increased the tissue water content of guinea‐pig renal cortical slices.

5. Depletion of cellular potassium (by preliminary incubation in oxygenated potassium‐free sodium Ringer with 10 m
M ouabain at 30° C) resulted in increased tissue water content when rabbit renal cortical slices were subsequently incubated in oxygenated choline Ringer at 25° C for 3 hr.

6. There was no evidence of energy‐dependent extrusion of water or ions from either equilibrated rat or rabbit renal cortical slices leached at 0·5° C and then reincubated at 25° C in choline Ringer.

7. Rat and guinea‐pig renal cortical slices leached at 0.5° C and reincubated at 25° C swelled in rubidium Ringer and in caesium Ringer. There was no evidence of energy‐dependent water or ion extrusion when metabolism was restored after leaching in either of these media. Metabolizing rat slices but not guinea‐pig slices swelled faster than slices whose metabolism was inhibited.

8. These results lend no support to the mechano‐chemical hypothesis which ascribes cellular volume regulation to a contractile mechanism squeezing isotonic extracellular fluid from the cells. Instead it is suggested that cellular water content in these experiments reflects the balance between the rate of loss of potassium (and chloride) from the cells and the rate of uptake of extracellular cation (and chloride) into the cells — these rates reflecting both the electrochemical potential gradients of the ions and membrane permeability to them. The implications in relation to the hypothesis of ouabain‐insensitive cellular volume regulation are discussed.
The effect of anaesthesia on the inhibition of pentagastrin‐evoked gastric acid secretion induced by atropine in the rat
Authors: Hedges A. R. , Parsons M. E.
Published: December 2014

1. In the anaesthetized, vagally intact rat, with a perfused gastric lumen, atropine produced a maximum inhibition of 60% of maximal pentagastrin‐evoked gastric acid secretion. Sub‐maximal pentagastrin‐stimulated secretion was also inhibited by atropine.

2. In the anaesthetized, vagotomized rat, with a perfused gastric lumen, atropine had no inhibitory effect on maximal pentagastrin‐evoked gastric acid secretion.

3. In the conscious fistula rat, atropine totally abolished both the basal gastric acid secretion and the maximal gastric acid secretion evoked by pentagastrin. In the anaesthetized chronic fistula rat, doses of atropine up to 1·6 mg.kg−1 administered subcutaneously produced a maximum inhibition of 70% of maximal pentagastrin‐evoked gastric acid secretion. Vagotomy did not affect the response to atropine.

4. In the conscious Heidenhain pouch rat, doses of atropine up to 1·6 mg.kg−1 administered subcutaneously produced a maximum inhibition of 70·9% of maximal pentagastrin‐evoked gastric acid secretion. Both anaesthesia and vagotomy, alone or in combination, did not affect the response to atropine.
Sensory fibres in ventral roots L7 and S1 in the cat
Authors: Coggeshall Richard E. , Ito Haruhide
Published: December 2014

1. Receptive fields were determined for ninety‐eight unmyelinated and 132 myelinated axons in the L7 and S1 cat ventral roots.

2. Seventy of the ninety‐eight unmyelinated axons had their receptive fields in somatic structures, the skin and deep tissues.

3. Of the seventy unmyelinated axons with somatic receptive fields, thirty‐five were mechanical nociceptors, fifteen were mechanical and thermal nociceptors, eleven were deep nociceptors, six were thermal receptors, and three were low threshold mechanoceptors.

4. Twenty‐four of the ninety‐eight unmyelinated axons had their receptive fields in visceral structures: the intestine, bladder and vagina.

5. We confirm the work of others that myelinated fibres attached to peripheral receptive fields can be found in ventral roots and that the receptive fields and functional qualities of these fibres are as one would expect of dorsal root fibres for the same segments.

6. A previous study demonstrated that approximately 30% of the axons in the L7 and S1 cat ventral roots are unmyelinated and arise from dorsal root ganglion cells. The present study confirms that these axons are sensory and that the axons are predominantly cutaneous nociceptors and visceral afferents. Thus it is concluded that the L7 and S1 cat ventral roots have a major sensory component.
Chemical energetics in repeated contractions of frog sartorius muscle at 0° C
Authors: Kushmerick M. J. , Paul R. J.
Published: December 2014

1. Recovery oxygen consumption (ΔO2) was measured in aerobic, unpoisoned frog sartorius muscles at 0° C following a series of repeated tetani.

2. For a series of tetani having nearly identical tension—time integrals, ΔO2 was dependent on the interval between tetani and reached a maximal value for intervals equal to or greater than 200 sec.

3. For a series of tetani at short (5 sec) intervals, ΔO2 was not distinguishable from ΔO2 following a single long tetanus having a tension‐time integral similar to that of the sum of the series.

4. A model is proposed to account for these observations in terms of the initial chemical reactions (Δ ∼ P) including a saturable non‐steady state reaction which utilizes about 1 μmole Δ ∼ P/g and which is superimposed on an energy utilization proportional to the tension—time integral. Measurements of ΔO2 and Δ ∼ P as functions of tetanic duration and interval between tetani are consistent with such a model.

5. These experiments show that, in addition to parameters usually considered, the previous contractile history of a muscle plays a significant role in determining the chemical energy cost of an isometric contraction.
Termination of transmitter release by stimulation of sodium‐potassium activated ATPase.
Authors: Vizi E S
Published: December 2014

1. The release of acetylcholine (ACh) from Auerbach's plexus of guinea‐pig ileum has been measured in eserinized Krebs solution using longitudinal muscle strip preparations. 2. Removal of the external K ions enhanced both the resting and stimulated release of ACh from the plexus. This effect was not affected by tetrodotoxin. 3. On readmission of K+ to tissues which had been suspended in K‐free Krebs solution the release of ACh was promptly reduced in both stimulated and unstimulated tissues. The extent of the reduction of ACh release depended on the exposure time to K‐free solution, the recovery being delayed by longer exposure. 4. The ACh releasing effect of (1,1‐dimethyl‐4‐phenyl‐piperazinium iodide (DMPP) was completely inhibited by the readmission of K ions to tissue which had been kept in K‐free Krebs solution. 5. Rb+ substitution for K+ produced no change in ACh release and addition of 5‐9 mM‐Rb after K removal reduced the release of ACh as K did readmission. When the K ions were substituted by Cs+, both the resting and stimulated release were enhanced. The amount of ACh released by a stimulus was enhanced both at low and high frequency of sustained stimulation. 6. Removal of the external K ions increased the release of tritiated noradrenaline (NA), from isolated rat iris; however, when K+ (5‐9 mM) was readmitted the release was reduced even below the control value. 7. It is concluded that the stimulation of (Na+‐K+)‐activated ATP‐ase in the membrane inhibits the release of transmitter, and under physiological condition Ca‐fluxes and the subsequent inhibition of membrane ATP‐ase may be involved in triggering the release of transmitter.
The functional significance of sodium channels in pancreatic beta‐cell membranes
Authors: Donatsch P. , Lowe D. A. , Richardson B. P. , Taylor Pamela
Published: December 2014

1. The existence and functional significance of Na channels in pancreatic β‐cell membranes were investigated by studying the effects of the plant alkaloid veratridine on the temporal release of insulin from perfused isolated rat islets of Langerhans.

2. 100 μ
M veratridine evoked a sustained threefold increase in insulin release which was almost completely inhibited by 3 μ
M tetrodotoxin (TTX). This action of TTX was rapidly reversible.

3. The simultaneous presence of 100 μ
M propranolol, 100 μ
M phenoxy‐benzamine and 10 μ
M atropine did not alter the magnitude of the response to 100 μ
M veratridine, indicating that the action of veratridine on the β‐cells was direct and was not mediated via the release of neurotrans‐mitters from nerve endings within the islets.

4. 45Ca uptake by isolated islets in static incubation was increased almost threefold by 100 μ
M veratridine. This increase was completely inhibited by the simultaneous presence of 3 μ
M TTX.

5. Replacement of Nao by choline caused a transient fourfold increase in insulin release which was associated with an increase in the uptake of 45Ca from the extracellular space of similar magnitude. Subsequent exposure of islets to 100 μ
M veratridine still evoked some insulin release but this only achieved 32% of that secreted by islets exposed to veratridine in medium of normal [Na]o.

6. The addition of 2·5 m
M CoCl2 to the medium caused a 62·5% inhibition of veratridine‐mediated insulin release.

7. In Ca‐free medium supplemented with 1 m
M EGTA, 100 μ
M veratridine evoked insulin release of equal magnitude and of similar temporal relationship to that obtained in the presence of normal [Ca]o.

8. A twofold increase in insulin release that occurred in the 15 min period immediately following exposure to 1 m
M ouabain was completely independent of [Ca]o. Subsequent ouabain‐evoked release became increasingly dependent on [Ca]o.

9. Tetrodotoxin (3 μ
M) inhibited the first phase of insulin release evoked by 16·7 m
M
d‐glucose by 37% and the second phase by 20%.

10. Both Na and Ca appear capable of entering through Na channels opened in the β‐cell membrane by veratridine. The increase in [Na]i, resulting from the veratridine mediated increase in PNa+, causes depolarization of the β‐cell membrane with a consequent opening of voltage‐sensitive, Co2+‐blockable channels for additional Ca entry. An increase in [Na]i also increases [Ca]i by altering the equilibria of intracellular Ca‐sequestering mechanisms. The small but significant reduction of glucose‐mediated insulin release by TTX indicates that glucose has a rather weak action on the Na channel and a more pronounced effect on the voltage‐dependent Co2+‐blockable Ca channel.
Mechansims and components of renal tubular acidification.
Authors: Cassola A C , Giebisch G , Malnic G
Published: December 2014

1. Renal cortical tubules of control and acetazolamide infused rats were perfused with 100 mM phosphate buffer at pH 5‐5. The rate of alkalinization was measured by means of antimony micro‐electrodes and was used to compute passive H ion fluxes from lumen to blood across the proximal and distal tubular epithelium. 2. The importance of other ionic movements that might contribute to pH changes of luminal buffers (chloride inflow into the lumen and bicarbonate diffusion across the epithelium) was assessed but found to be minor. H ion movements accounted for the majority of the observed pH changes. 3. H ion permeability of the tubular wall was calculated from the measured H fluxes and transepithelial concentration differences. It was 1‐10 cm/sec, several orders of magnitude larger than those for other ions. However, such values are compatible with the mobility of protons in a medium of structure water within the limiting membrane. 4. A kinetic analysis of the mechanism of movement of H ions across the renal tubule is presented on the basis of experiments in which acidification and alkalinization of luminal buffers was followed in stationary microperfusions. The data are compatible with a pump‐leak system in the proximal tubule, and with a model with low H ion permeability and a gradient dependent pump in the distal tubule.