bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of nephrectomy and KCl on transmembrane potentials, intracellular electrolytes, and cell pH of rat muscle and liver in vivo
Authors: Williams J. A. , Withrow C. D. , Woodbury D. M. 
Published: December 2014

1. The ability of 24 hr nephrectomy and KCl to raise plasma K+ concentration was used to correlate transmembrane resting potential (RP), ionic gradients, and cell pH (DMO method) in rat muscle and liver in vitro.2. Effects of 24 hr nephrectomy on electrolytes included a rise in plasma K+ and fall in Na+, with a rise in intracellular K+ and fall in intracellular Na+ in both liver and muscle. Intracellular Cl− concentration rose in muscle and decreased in liver.3. Measured muscle RP was decreased from −91 to −77 mV by 24 hr nephrectomy, with the RP predictable from the Goldman equation for Na+ and K+ with PNa/PK = 0·01 and Cl− behaving as if passively distributed.4. Measured hepatic RP was increased from −43 to −48 mV by 24 hr nephrectomy, with a change in ionic permeability or activation of an electrogenic pump necessary to explain the results.5. Plasma acid—base changes consisted of metabolic acidosis with partial respiratory compensation. Cell pH rose slightly in both liver and muscle; the H+ gradient remained constant in muscle but increased slightly in liver.6. KCl was injected into intact rats while the RPs were continuously measured in muscle or liver. Muscle RP was found to decrease and hepatic RP to increase along a similar time course.7. Infusion of KCl into the portal vein led to an increase in the hepatic RP for values of hepatic venous K+ of 15–25 m
M, whereas infusion sufficient to increase the hepatic venous K+ concentration to 30–40 m
M produced no change or a slight decrease in hepatic RP.8. The rat muscle RP can be adequately described by the Goldman equation for Na+ and K+, whereas the hepatic RP may well have both diffusion and electrogenic components which respond differently to an increase in plasma K+ concentration.
Rat gastric acid secretion studies with histamine and synthetic gastrin‐like pentapeptide
Authors: James R. M. V. 
Published: December 2014

1. Gastric acid secretion was measured in the urethane anaesthetized rat whilst maintaining a recirculated gastric perfusion fluid at pH 4.2. The latent period of onset of secretion following single intravenous doses of histamine and pentapeptide in combination was significantly shorter than that following either stimulant alone.3. When administered over a period of 2 hr the maximal steady rate of secretion in response to pentapeptide was 75% of that to histamine.4. Acid stimulatory effects were additive both when the drugs were given concurrently over a 2 hr period and when one was administered after a maximal response had been obtained to the other.5. Although there is some evidence to indicate that histamine and pentapeptide might be initiating acid secretion by different mechanisms it is suggested that they may not be acting with total independence.
Abnormalities of 5‐hydroxytryptamine uptake and binding by blood platelets from children with Down's syndrome
Authors: Boullin D. J. , O'Brien R. A. 
Published: December 2014

1. Blood platelets from normal children and children with the trisomy 21 form of Down's syndrome (mongolism) were studied to determine the cause of the well established reduction in platelet 5‐HT in the disease.2. Concentrations of endogenous 5‐HT in the platelets from mongols were 25·3% of the concentrations found in normal children.3. The net accumulation of 5‐HT in the mongol cells was decreased to 52·7% of normal. This reduction was probably due, in part, to a defect in 5‐HT transport, because the initial rates of 5‐HT uptake at plasma concentrations of 10−6 and 10−5
M were significantly slower.4. Experiments on the efflux of 5‐HT from mongol platelets loaded with amine showed that the rate of loss was initially 2·6 and later 7·8 times faster than normal.5. Platelet ATP in mongol cells was 26% of normal, and the reduction of ATP and 5‐HT was in the molar ratio of 3:1.6. It is considered that the low platelet 5‐HT in Down's syndrome is due to a defective 5‐HT transport mechanism and impaired 5‐HT binding, resulting from a reduction in the essential binding substance, ATP.
The role of sodium and calcium ions in the hypothalamus in the control of body temperature of the unanaesthetized cat
Authors: Myers R. D. , Veale W. L. 
Published: December 2014

1. Isolated regions of the anterior, posterior and other areas of the hypothalamus of the unanaesthetized cat were perfused by means of push‐pull cannulae lowered through permanently implanted guide tubes. Each site was perfused for a 30 min interval at a rate of 50 μl./min. Concentrations of sodium, calcium, potassium and magnesium ions in the perfusate were altered selectively.2. Sodium ions in a concentration which varied from 13·6 to 68·0 m
M in excess of the level in extracellular fluid caused a steep rise in the temperature of the cat when the solution was perfused at sites located within the posterior hypothalamic area. Shivering, vasoconstriction, and piloerection accompanied the increase in temperature. When the chloride was replaced in the perfusate by the toluene‐p‐sulphonate salt of sodium, the hyperthermia was equally intense. Solutions containing excess sodium ions perfused within the anterior and other hypothalamic areas produced either a slight fall or rise in temperature as well as other physiological changes.3. Calcium ions in a concentration which varied from 2·6 to 10·4 m
M in excess of the physiological level perfused at the same sites within the posterior region of the hypothalamus produced a sharp fall in body temperature, which was accompanied by vasodilatation and a decrease in the activity of the cat. When solutions containing excess calcium were perfused in the anterior and other hypothalamic areas, no consistent change in temperature occurred.4. Potassium or magnesium ions in concentrations which varied from two to ten times the level in extracellular fluid had virtually no effect on the temperature of the cat when they were perfused in the anterior, posterior or other areas of the hypothalamus.5. We conclude that the constancy in the ratio between sodium and calcium ions in the posterior hypothalamus may be the inherent mechanism by which the set‐point for body temperature is determined.
Ionic mechanism of post‐tetanic potentiation at the neuromuscular junction of the frog
Authors: Weinreich D. 
Published: December 2014

1. Transmitter release at the frog neuromuscular junction was studied after sodium influx in nerve and muscle was abolished by tetrodotoxin (TTX).2. In the presence of TTX, transmitter release evoked by electrotonic depolarization of the nerve terminal was potentiated following presynaptic stimulation by a train of depolarizing pulses.3. Post‐tetanic potentiation (PTP) in the presence of TTX appeared no different from that observed in control (TTX‐free) muscles. The magnitude as well as the time course of PTP was dependent on the number of tetanic stimuli and on temperature of the medium when sodium influx was inhibited by TTX.4. When external sodium was replaced by an isotonic calcium chloride solution PTP was still present. Ionophoretic application of calcium during tetanic nerve stimulation and increase in the intensity of the depolarizing pulse of the train, which presumably enhances calcium movements into nerve endings, caused a large increase in the duration of PTP.5. It is concluded that PTP does not require sodium but depends on movement of calcium from the external medium into the nerve terminal.
The relative contribution of K and Cl to the total increase of membrane conductance produced by adrenaline on the smooth muscle of guinea‐pig taenia coli
Authors: Ohashi H. 
Published: December 2014

1. The relative contribution of K and Cl to the total increase of membrane conductance produced by adrenaline on the smooth muscle of guinea‐pig taenia coli has been investigated. Constant current pulses were applied with a pair of large external electrodes, the voltage change was recorded with an intracellular micro‐electrode, and the change in the size of the electrotonic potential by adrenaline was measured.2. Adrenaline hyperpolarized the membrane by about 8 mV with a range from 5 to 15 mV and it reduced both the size and the time course of the electrotonic potential. On the average the size was reduced to 65 ± 1·8% (n = 75) of the normal size, from which a decrease of the membrane resistance to 45 ± 2·2% was calculated, or 48% allowing for the spatial decay.3. The magnitude of the reduction of the electrotonic potential caused by adrenaline was decreased as the concentration of K or Cl ions in the medium was reduced by substituting NaCl or sucrose for KCl or an impermeant anion, benzene sulphonate, for Cl ions. The adrenaline effect remained unaltered when the NaCl was replaced with Tris‐Cl.4. It is therefore concluded that adrenaline opens the ion pathways mainly for K and Cl.5. On the basis of the changes in potential and in conductance caused by adrenaline, the equilibrium potential for its action was calculated as − 75 mV.6. The ratio of the Cl component to the K component of the additional conductance increase was obtained as 0·36 using the calculated equilibrium potential and the Nernst potentials for K (−91 mV) and Cl (‐31 mV).
The contribution of mechanical factors to the early adaptation of the spindle response
Authors: Husmark I. , Ottoson D. 
Published: December 2014

1. Adaptation in terms of the early fall of the receptor potential was studied in isolated frog spindles. The contribution of gross mechanical changes to the decline of the response was determined by comparing the responses obtained under constant length and under constant tension.2. It was found that the early adaptation under constant stretch increased with increasing lengthening of the spindle for stretches up to 25–30% of the resting length and decreased with still stronger stretches. When the spindle was stretched by 100% or more the static phase of the receptor potential reached nearly the same height as the dynamic peak and the early adaptation approached zero.3. The early adaptation decreased with decreasing velocity of linearly rising stretch and approached zero for stretches below about 0·5 mm/sec.4. For different strengths of a steplike stretch the amount of early adaptation was linearly related to the fall in tension over the same period. The relative amount of tension fall, however, was always less than the corresponding fall of the response.5. The early adaptation was 15–20% smaller under constant tension than under constant length for stretches below the level giving the maximum dynamic peak.6. The results suggest that a comparatively small amount of the early adaptation of the spindle response to constant stretch is related to gross alterations in length in different regions of the spindle. The main part of the adaptive fall of the response is probably related to functional properties of the sensory membrane and to the ionic mechanism underlying the production of the receptor potential.
The effect of light chloralose and pentobarbitone anaesthesia on the acid—base state and oxygenation of arterial blood in dogs
Authors: Ledsome J. R. , Linden R. J. , Norman J. 
Published: December 2014

1. The effects of light anaesthesia of approximately 8 hr duration using either pentobarbitone or chloralose on the acid—base balance and oxygenation of arterial blood were determined in dogs breathing spontaneously.2. With pentobarbitone anaesthesia there was a slight initial respiratory acidaemia.3. With chloralose there was a non‐respiratory acidaemia which was probably the result of using an unbuffered solvent.4. Changes in the acid—base balance and the oxygen concentration of the arterial blood over the course of each experiment were minimal.5. In one animal a pH of 7·07 was recorded; in others the oxygen tension on occasion was between 50 and 60 mm Hg. The value of monitoring the acid—base state and the oxygenation of blood in experimental preparations is discussed.
Biophysical properties of the longitudinal smooth muscle of the guinea‐pig rectum
Authors: Kuriyama H. , Mekata F. 
Published: December 2014

1. The membrane properties of the longitudinal muscle layer of the guinea‐pig rectum were studied in hypertonic solution (twice the normal Krebs by addition of sucrose) by the micro‐electrode technique. To produce the electrotonic potential and spike, stimulating partitions were used.2. Hypertonic solution hyperpolarized the membrane and increased the membrane resistance. However, no change in the space constant was observed before and after treatment with hypertonic solution.3. The appearance and amplitude of the spike became regular after treatment with hypertonic solution and appearance of the overshoot was consistent.4. The characteristic constants and the conduction velocity were measured in hypertonic solution.(i) The space constant of the membrane was 0·81 mm, the time constant of the electrotonic potential was 83·7 msec and the time constant of the foot of the propagated spike was 8·8 msec.(ii) The conduction velocity of the excitation measured by insertions of the two micro‐electrodes was 4·4 cm/sec.(iii) The chronaxie of the membrane was 71·3 msec.5. The results obtained from the present experiments were discussed in relation to the cable theory, and it was concluded that the passive properties of the membrane of the rectal smooth muscle could be explained by the cable equations.6. The specificities of the electrical properties of rectal smooth muscle were compared with muscle from other regions of the alimentary canal.
Lack of involvement of fusimotor activation in movements of the foot produced by electrical stimulation of monkey cerebral cortex
Authors: Lewis M. McD. , Porter R. 
Published: December 2014

1. Contractions of the small muscles of the foot producing flexion and adduction of the hallux were elicited by brief trains of electrical stimulation of a motor point on the precentral gyrus of anaesthetized monkeys and these contractions were recorded myographically.2. The cortical stimulus intensities necessary to produce minimal muscle contractions were measured for different frequencies of stimulation at the cortical point, and the latency of the minimal muscle contraction was measured in each case.3. Section of all the relevant lumbar and sacral dorsal roots had no effect on the threshold stimulus currents necessary to produce minimal contractions or on the latencies of these responses. Hence, in the anaesthetized monkey, the power of the cortico‐fusimotor activity stirred up by electrical stimulation of the cortex is inadequate to influence significantly the motor responses of the most accessible muscles.
The effect of insulin and insulin deficiency on the transport and metabolism of glucose by rat small intestine
Authors: Leese H. J. , Mansford K. R. L. 
Published: December 2014

1. Insulin deficiency induced by anti‐insulin serum or streptozotocin increased glucose absorption, as measured in everted sacs of rat upper ileum incubated for 30 min with oxygenated Krebs—Henseleit bicarbonate medium.2. Everted sacs prepared from the terminal ileum of insulin‐deficient rats were able to accumulate glucose against a concentration gradient (i.e. development of active glucose transport).3. In experimental diabetes induced by streptozotocin, everted sacs of upper ileum showed increased 3‐methyl glucose active transport, and sacs of terminal ileum showed development of 3‐methyl glucose active transport.4. Lactic acid formation during the absorption of both glucose and 3‐methyl glucose was increased approximately twofold in everted sacs of insulin‐deficient animals.5. Insulin added at 100 mu./ml. to the incubating media of everted sacs prepared from insulin‐deficient rats did not result in a reduction of glucose absorption or reverse the other effects.6. Fluoride (5 × 10−3
M) added to the serosal and mucosal media of sacs of terminal ileum prepared from insulin‐deficient rats decreased [14C]CO2 formation from [U‐14C]glucose and lactate formation during glucose absorption, but was unable to reverse the effect of insulin deficiency on glucose active transport.7. The effects of insulin deficiency induced by streptozotocin were more striking than those induced by anti‐insulin serum.8. Everted sacs prepared from rats starved for 3 days showed increased glucose active transport accompanied by diminished conversion of [U‐14C]glucose to [14C]CO2.9. The possible role of hexokinase is discussed in relation to these findings.
Prediction of repetitive firing behaviour from voltage clamp data on an isolated neurone soma
Authors: Connor J. A. , Stevens C. F. 
Published: December 2014

1. Membrane parameters of an isolated neural cell body have been determined by voltage clamp analysis. Data are expressed as membrane ion‐specific conductances, leak conductance, and capacitance.2. Three ionic currents are present: Inward, II; and two operationally distinct outward currents, IK and IA. Both outward currents are apparently carried by potassium ions.3. Hodgkin—Huxley‐like equations were solved for the discharge of two sequential action potentials in response to a constant stimulus current. The digital computer solutions are compared with action potential data recorded from the investigated cell.4. The computed and experimentally measured relationships between firing frequency and stimulus current intensity are compared and are linear over the same portion of the total frequency range.5. Cell behaviour in the latter part of the interspike interval is dominated by the conductance gA while gNa and gK largely determine the character of the action potential and the initial portion of the interspike interval.6. Prehyperpolarization of the membrane activates gA and the membrane response to depolarizing current differs markedly from the response elicited when no prehyperpolarization is imposed.
Effect of prostigmine on the time course of the end‐plate potential in the rat diaphragm
Authors: Kuba K. , Tomita T. 
Published: December 2014

1. End‐plate potentials (e.p.p.s) were evoked by applying brief depolarizing pulses to motor nerve endings in a phrenic nerve—diaphragm preparation paralysed by tetrodotoxin (TTX). Without prostigmine, the time to decay from the summit of the e.p.p. to half amplitude (the half‐decay time) was roughly constant (2–4 msec) when the amplitude was increased by increasing stimulus intensity or duration.2. In the presence of prostigmine (5 × 10−7‐2 × 10−5 g/ml.), the falling phase of the e.p.p. was different in time course depending on the amplitude. The half‐decay time had, very roughly, an exponential dependence on amplitude. The relationship was not affected by increasing the TTX or the prostigmine concentration, but
D‐tubocurarine (10−6 g/ml.) made the relationship less steep.3. Hyperpolarizing current pulses, applied after the depolarizing current pulse which produced the e.p.p., had no effect on the time course of the e.p.p. No facilitating effect of repetitive stimulation was observed without prostigmine up to a frequency of 40 c/s, but there was a strong effect of repetitive stimulation in increasing the amplitude and duration of the e.p.p. in the presence of prostigmine. During stimulation, the endplate was continuously depolarized by 10–20 mV, and its recovery was very slow, the half‐decay time being about 3 sec.4. The half‐decay time of the acetylcholine potentials produced by iontophoretically applied acetylcholine was almost independent of the amplitude, with or without prostigmine, although it increased the amplitude of the potential and prolonged the falling phase.5. Possible mechanisms for the alteration of the falling phase of the e.p.p. were discussed. It is speculated that, in the presence of prostigmine, a process which is involved in a conductance increase of the post‐synaptic membrane, after acetylcholine has combined with the receptor molecules, is the main factor determining the falling phase of the e.p.p.
A search for odour encoding in the olfactory lobe
Authors: Yamada Minoru 
Published: December 2014

1. Studies were made of quality coding in the olfactory lobe of the insect by recording extracellular action potentials from single cells.2. Listing cell spectra permits to distinguish two main groups of cells, namely, ‘odour specialist’ which respond very specifically to biologically important substances and ‘odour generalist’ which respond to a large variety of odorants (thirty‐two compounds) in an excitatory or inhibitory manner, or not responding at all.3. Among more than fifty cells of the ‘odour generalists’, very few had similar, or identical, reaction spectra to an arbitrarily chosen set of thirty‐two odorants, while the ‘odour specialists’ are like each other in their response spectra.4. There was an indication of a regional and layer differentiation of response in the lobe to the sex attractant.5. ‘On’, ‘on—off’, and ‘off’ response types, as well as several variations on these response types, were found in single units during odour presentations.6. Differences in patterning of excitation for each of the thirty‐two compounds can be readily detected by the comparison of the relative amounts of activity in each of the eighty‐one units tested. It is therefore concluded that the mechanism of odour encoding at the olfactory lobe may involve the linear combinations of every olfactory neurone's activity result ing in a unique across‐lobe pattern of discharges (‘odour code pattern’) for each particular odorant.7. If it follows that odour discrimination by the lobe depends on such differences of ‘odour code patterns’, it would be possible then to distinguish very many odorants simply by having very many neurones possessing differential odour specificity.
Noradrenaline release from isolated muscles of the nictitating membrane of the cat
Authors: Langer S. Z. , Vogt Marthe 
Published: December 2014

1. When the splanchnic nerves were stimulated in the cat for periods of up to 2 hr, the amount of adrenaline taken up by the nictitating membrane was very small; the highest figure was 0·37 μg/g, corrected for losses.2. The noradrenaline (NA) stores of the isolated medial muscle of the nictitating membrane were labelled with [3H]NA, and field stimulation of single muscles was carried out in a small organ bath. A stimulation period of 5 min with supramaximal shocks delivered at a frequency of 25/sec produced a mean release of NA into the bath fluid of 0·46 ± 0·13 μg/g (uncorrected). Phenoxybenzamine, 10 μg/ml., increased this figure by a factor of 2‐3·6. When corrections were made for the amount of transmitter metabolized before it could be collected, 47% of the tissue content of NA were shown to be released during the 5 min stimulation of the normal membrane, and about 55% in the presence of phenoxybenzamine. Prolonged stimulation of a phenoxybenzamine‐treated membrane was apt to lead to loss of tissue stores of NA.3. Calculation of the degree of labelling of the NA in the tissue, and of NA released by stimulation, indicated that about 21% of endogenous NA had been replaced by labelled compound both in the tissue and in the overflow.4. Transmitter release per pulse was estimated by applying 720–1330 shocks at frequencies of 4 or 6/sec to membranes exposed to phenoxybenzamine. Mean release of NA per shock and per g tissue was 1·3 ng (corrected for losses). This represents 3·5 × 10−4 of the tissue content determined at the end of the experiment.