bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effect of muscle length and rate of fusimotor stimulation on the frequency of discharge in primary endings from muscle spindles in the cat
Authors: Lewis D. M. , Proske U. 
Published: December 2014

1. Responses from the primary endings of muscle spindles in the soleus muscle of the cat were recorded during repetitive fusimotor stimulation at a number of different muscle lengths.2. An increase in the rate of stimulation increased the size of both the peak and the plateau of the responses to stimulation of both static and dynamic fusimotor fibres.3. Responses, with the exception of the peak frequency of the discharge during dynamic fusimotor stimulation, increased in size on raising the muscle length up to maximum body length. The peak of the dynamic response reached its highest value at intermediate lengths.4. The effect of increasing stimulation rate and muscle length was to reduce both the latency and time to peak of fusimotor responses. The change in latency with muscle length was particularly dramatic at low stimulus rates.5. In an attempt to compare fusimotor responses with the behaviour of extrafusal muscle fibres, a model is proposed which consists of a mixture of extrafusal tension and rate of change of tension. This model could simulate the static fusimotor responses reported here.
Synaptic actions of single interneurones mediating reciprocal Ia inhibition of motoneurones
Authors: Jankowska Elżbieta , Roberts W. J. 
Published: December 2014

1. The investigation was aimed at defining the function of the interneurones which, according to indirect evidence, mediate the reciprocal Ia inhibition of motoneurones (Hultborn, Jankowska & Lindstrom, 1971 b) by studying their direct synaptic actions. These actions were tested by recording post‐synaptic potentials in motoneurones following spike activity of single interneurones activated by iontophoretic application of glutamate. The interneurones were found to produce unitary monosynaptic IPSPs in those motoneurones in which disynaptic IPSPs are evoked by the group Ia afferents which monosynaptically excite the interneurones.2. Unitary IPSPs were found in more than 80% of the motoneurones impaled in the immediate vicinity of the axonal branches of the investigated Q interneurones in the PBSt motor nucleus. It is estimated that each interneurone might inhibit about every fifth PBSt motoneurone. The amplitudes of the unitary IPSPs ranged between 8 and 220 μV and were 10–200 times smaller than the maximal Ia IPSPs evoked in the same motoneurones.3. The synaptic delay in the generation of unitary IPSPs was measured in relation to the spike potentials recorded from the terminal branches of interneurones in the immediate vicinity of the impaled motoneurones. The synaptic delays ranged between 0·28 and 0·42 msec.4. From chloride reversal tests and an analysis of the time course of the unitary IPSPs it was concluded that the terminals of the investigated interneurones make synaptic contact predominantly on the soma and/or on the proximal parts of the dendrites of the motoneurones, their distribution being, however, not quite uniform.
Calcium uptake and force development by skinned muscle fibres in EGTA buffered solutions
Authors: Ford L. E. , Podolsky R. J. 
Published: December 2014

1. The uptake of 45Ca and the development of force by segments of skinned muscle fibres were measured in Ca solutions buffered with EGTA. When the Ca ion concentration in these solutions was above the contraction threshold, Ca was accumulated by the sarcoplasmic reticulum during the delay phase before force developed. The uptake rate increased, and the length of the delay decreased, when the concentration of the calcium buffer was increased.2. The maximum accumulation of Ca was 2–3 m
M. Force developed, ending the delay phase, when the calcium uptake approached this maximum level.3. The pattern of force development suggested that this process was often accompanied by a sudden release of accumulated Ca.4. The relation between the kinetics of 45Ca uptake and the interaction of calcium with EGTA and the sarcoplasmic reticulum is discussed. The data indicate that at the low concentrations necessary for relaxation the sarcoplasmic reticulum takes up Ca fast enough to account for the rate at which force falls when intact muscle fibres relax.
The isolation of a renally active substance from arterial blood
Authors: Lockett Mary F. , Retallack R. W. 
Published: December 2014

1. A substance (Art. HS) which resembles the 18‐monoacetate of
D‐aldosterone (18 MA) in its biological actions is found in arterial blood of cats and sheep: Art. HS is assayed in terms of antidiuretic activity equivalent to synthetic 18 MA.2. In cats under chloralose anaesthesia, dialysis of arterial blood (2–3 ml./min) in a small external circuit (8–15 ml.) without disturbance of heart rate, blood pressure or respiration, predicts a physiological concentration of Art. HS equivalent to 31·5–51·9 ng 18 MA/100 ml. Efficiency of dialysis assumed in this calculation is 100%.3. Art. HS is almost evenly distributed throughout the plasma and formed elements of blood.4. Concentrations of Art. HS found during severe arterial haemorrhage are equivalent to 188 ± 6·7 and 151 ± 9·2 ng 18 MA/100 ml. in cats and sheep respectively.5. Art. HS has been isolated from 27·6 l. sheep arterial blood by ethyl acetate: chloroform 1:1 extraction, defatting by partitioning between methanol and petroleum ether and purifying by seven‐stage thin layer chromatography on MN Kieselgel UV254. Final yield was equivalent in activity to 21·6 μg 18 MA. Synthetic 18 MA was used as RF marker. Spots of 2 μg 18 MA are visible on MN Kieselgel UV under U.V. Art. HS activity equivalent to 21·6 μg 18 MA cannot be seen.6. Art. HS was not detectable in IVC blood of cats under chloralose anaesthesia during haemorrhage. The threshold for detection was the equivalent of 15–20 ng 18 MA/100 ml.7. Art. HS resembles a substance liberated by the heart (Lockett & Retallack, 1970a, b, 1971) in chromatographic properties, biological properties and stability in aqueous solution. Art. HS is very much more stable in aqueous solution than 18 MA.
The release of prostaglandins and progestin into the utero‐ovarian venous blood of guinea‐pigs during the oestrous cycle and following oestrogen treatment
Authors: Blatchley F. R. , Donovan B. T. , Horton E. W. , Poyser N. L. 
Published: December 2014

1. Blood was collected from the utero‐ovarian vein of guinea‐pigs on days 3, 9, 10, 11, 12, 13, 14 and 15 of the oestrous cycle, and from animals injected with oestrogen over days 4–6 and used on day 7. The content of prostaglandin F2α and E2 was determined by bio‐assay and gas chromatography‐mass spectrometry, and of progestin by competitive protein binding assay.2. The concentration of prostaglandin F2α on day 3 was 14·1 ng/ml.; it fell below detectable limits on day 7, but after day 11 the concentration rose to between 15·7–17·2 ng/ml. A value of 60·7 ng/ml. was recorded on day 15.3. The release of prostaglandin F2α was increased in animals pre‐treated with oestrogen but was below threshold levels in similarly treated hysterectomized females.4. Prostaglandin E2 was not detectable in blood collected on days 3, 9, 10, 11 and 12. From a threshold value of 1·1 ng/ml. on day 13, the concentration rose to 5·4 ng/ml. on day 14 and to 54·9 ng/ml. on day 15.5. The progestin concentration rose from 66 ng/ml. on day 3 to values of 80–180 ng/ml. between days 9–14. It fell to 45 ng/ml. between days 14 and 15.6. This work establishes that prostaglandin F2α is released into the utero‐ovarian venous blood, and that its concentration fluctuates in the course of the oestrous cycle and can be related to changes in luteal function.
Effect of acid‐base alterations on hepatic lactate utilization
Authors: Goldstein Philip J. , Simmons Daniel H. , Tashkin Donald P. 
Published: December 2014

1. The effect of acid‐base changes on hepatic lactate utilization was investigated in anaesthetized, mechanically ventilated dogs.2. Portal vein flow and hepatic artery flow were measured with electromagnetic flowmeters, lactate concentration of portal vein, arterial and mixed hepatic venous blood was determined by an enzymatic technique, and hepatic lactate uptake was calculated using the Fick principle.3. Respiratory alkalosis (Δ pH 0·25 ± 0·02) in four dogs resulted in a significant fall in total hepatic blood flow (−22 ± 4%) and a significant rise in both arterial lactate concentration (2·18 ± 0·32 m‐mole/l.) and hepatic lactate utilization (3·9 ± 1·2 μmole/min.kg).4. 0·6
M‐Tris buffer infusion (Δ pH 0·21 ± 0·02) in four dogs produced no significant changes in liver blood flow, arterial lactate concentration or hepatic lactate uptake.5. Respiratory acidosis (Δ pH −0·20 ± 0·03) in six dogs and metabolic acidosis (Δ pH −0·20 ± 0·02) in four dogs produced no significant changes in liver blood flow, decreases in arterial lactate concentration of 0·38 ± 0·09 m‐mole/l. (P < 0·05) and 0·13 ± 0·13 m‐mole/l., respectively, and no significant changes in hepatic lactate uptake.6. A significant correlation (r = 0·63; P < 0·01) was found between hepatic lactate utilization and arterial lactate concentration during the hyperlactataemia associated with respiratory alkalosis.7. Hyperlactataemia induced in four dogs by infusion of buffered sodium lactate (Δ pH 0·05 ± 0·01;% Δ liver blood flow 29 ± 7%) was also significantly correlated with hepatic lactate utilization (r = 0·70; P < 0·01) and the slope of the regression was similar to that during respiratory alkalosis.8. These data suggest that the hyperlactataemia of alkalosis is not due to impaired hepatic utilization of lactate and that the principal determinant of hepatic lactate uptake during alkalosis or lactate infusion is blood lactate concentration, rather than liver blood flow or acid‐base status.
Absence of compensatory renal hypertrophy in baboons
Authors: Dicker S. E. , Morris Christine A. 
Published: December 2014

1. The weights of kidneys of fifteen adolescent and forty‐six adult male baboons were estimated. In contrast with what has been described in other mammals, in the majority of baboons (thirty‐nine out of fifty‐seven) the left kidney was heavier than the right.2. The medulla/cortex ratio was of the order of 1·8. The maximum urinary concentration, after 36 hr of food and water deprivation, averaged 1050 ± 80 m‐osmole/kg H2O.3. Unilateral nephrectomy was performed in twelve baboons with body weight ranging from 5 to 14 kg. In six animals, the left kidney was removed and the right kidney in the others.4. In two baboons, the left kidney was transplanted to the left iliac artery and vein, the ureters being left intact. After a few weeks, the right kidney was taken out, and the animals were kept under observation, one for a further 3 months and the other for a further 4 months.5. In none of the animals, whether after simple unilateral nephrectomy or after unilateral nephrectomy following transplant of one kidney, did the renoprival kidney show any significant enlargement.6. After unilateral nephrectomy, the health of the animals remained excellent, all the baboons increasing in body weight. The ability to concentrate urine by the renoprival kidney was not impaired.7. In contrast with what has been described in mice and rats, in unilaterally nephrectomized baboons no significant changes in the concentration of either RNA or DNA in renal cortex and medulla of the contralateral kidney were observed.8. After unilateral nephrectomy in baboons, there was a marked increase of oxygen uptake in slices from the cortex, but not from the medulla. In contrast with what had been observed in rats where the enhanced rate of oxygen uptake returned to pre‐operative values, in baboons no decrease was observed, the rate of oxygen uptake remaining high during the whole period of observation.9. In the limit of time of observation (maximum 4 months) there was no evidence that unilateral nephrectomy resulted in compensatory hypertrophy of the contralateral kidney.
The effect of low temperature on the excitation‐contraction coupling phenomena of frog single muscle fibres
Authors: Caputo Carlo 
Published: December 2014

1. Potassium contractures are affected by low temperature: the maximum contracture tension is diminished by about 15% at 3° C, while the response time course is greatly prolonged.2. The contractile threshold for potassium contractures is lowered by about 10 mV at 3° C.3. The fibre's membrane is depolarized by approximately the same amount when exposed to solutions with increased potassium concentrations at 20 or 3° C.4. The repriming process, that is, the process by which the fibres recover their contractile ability following a potassium contracture, proceeds about six times slower at 3° C. This effect is not due to failure of the fibres to repolarize in the cold when transferred from a high potassium to a low potassium medium.5. At low temperature repolarization occurs, even though it is somewhat slower. Following the solution change, from 190 m
M potassium to a low potassium solution, the initial rate of repolarization is 8·5 mV/sec at 20° C, and 3·4 mV/sec at 3° C. This effect is not sufficient to account for the delay in the repriming process.6. After a potassium contracture, recovery of the fibre's twitching ability at 3° C is also delayed. At a time when twitches have not yet been recovered, membrane potentials of −90 mV and almost normal action potentials can be recorded.
Post‐stimulus hyperpolarization and slow potassium conductance increase in Aplysia giant neurone
Authors: Brodwick M. S. , Junge D. 
Published: December 2014

1. Intracellular records from Aplysia giant (R2) cell somata showed long lasting 4–10 mV hyperpolarizations after passage of outward current through a second intracellular electrode.2. An increase in membrane slope conductance occurred simultaneously with the post‐stimulus hyperpolarization (PSH).3. Both the PSH and conductance‐increase varied strongly with stimulus amplitude and duration.4. Both the PSH and the conductance increase occurred in Ca‐free medium containing tetrodotoxin, when action‐potential production was completely blocked.5. The PSH persisted in the presence of ouabain or DNP, with cooling, with removal of external K+, and in media where all the Na+ was replaced with Li+, suggesting that it was not due to the activity of an electrogenic pump.6. A reversal potential for the PSH was demonstrated by application of maintained inward current following the end of an outward‐directed stimulus.7. The PSH reversal potential varied with [K]o, but not with [Cl]o or [Na]o, suggesting that the PSH was mainly due to an increase in K conductance.8. The PSH and the conductance increase were reduced strongly when all the Na+ was replaced with Tris, and only slightly when Na+ was replaced with sucrose.
Potassium activated phosphatase from human red blood cells. The effects of p‐nitrophenylphosphate on cation fluxes
Authors: Garrahan P. J. , Rega A. F. 
Published: December 2014

1. When red cells are incubated in solutions containing p‐nitrophenyl‐phosphate (p‐NPP), intracellular p‐NPP quickly builds up reaching with a half‐time of 3 min a concentration in cell water equal to one fourth the external concentration, which under the conditions used is the expected value for a divalent anion in Gibbs—Donnan equilibrium. Hence p‐NPP added to the incubation media in red cells has quick access to the active centre of the membrane phosphatase which is located at the inner surface of the cell membrane.2. When p‐NPP is added to the incubation media of ATP‐free red cells or reconstituted ghosts, no ouabain‐sensitive cation movements are detectable, suggesting that hydrolysis of p‐NPP by the active transport system is unable to energize active ion translocation.3. When p‐NPP concentration in the incubation media of ATP‐containing cells is progressively raised, both ouabain‐sensitive Na loss and ouabain‐sensitive Rb uptake tend to zero along rectangular hyperbolae. For both movements inhibition is half‐maximal at 77 m
M external p‐NPP (i.e. 19 m
M internal p‐NPP).4. p‐NPP inhibits with equal effectiveness the Na:K and the Na:Na exchanges catalysed by the Na pump.5. The inhibitory effect of p‐NPP cannot be attributed to the products of its hydrolysis, is inversely related to the intracellular ATP concentration and seems to be exerted at the inner surface of the cell membrane with an apparent affinity similar to that of the membrane phosphatase. These facts suggest that inhibition is mediated by the combination of p‐NPP with the active centre of the membrane phosphatase.6. Apart from affecting the ouabain‐sensitive cation movements, p‐NPP increases the ouabain‐resistant uptake and loss of both Na and Rb. This effect is about 4 times larger for Rb than for Na, and its kinetic analysis suggests that it is due to an increase in the passive permeability of the cell membrane.7. The increase in passive cation permeability upon addition of p‐NPP cannot be attributed to the products of its hydrolysis. It seems to be due to the combination of p‐NPP with a site which, like the active centre of the ouabain‐resistant membrane phosphatase, faces the inner surface of the cell membrane, is unaffected by ATP and is half saturated by about 15 m
M‐p NPP.
Thermoregulatory effects of intraventricular injection of noradrenaline in the mouse and the influence of ambient temperature
Authors: Handley Sheila L. , Spencer P. S. J. 
Published: December 2014

1. At an ambient temperature of 20° C, intraventricular injection of noradrenaline in the mouse resulted in hypothermia accompanied by a fall in metabolic rate and by cutaneous vasodilatation. Subcutaneous injection of noradrenaline resulted in hyperthermia with raised metabolic rate and cutaneous vasodilatation.2. The hypothermia and fall in oxygen consumption rate following intraventricular noradrenaline were prevented by pre‐treatment with subcutaneous propranolol, while the cutaneous vasodilatation was un‐affected. However, the effects of subcutaneously injected noradrenaline were completely abolished by subcutaneous propranolol. Intraventricular propranolol did not modify the hypothermic effect of intraventricular noradrenaline.3. The direction of the effect on body temperature of intraventricular noradrenaline was dependent upon ambient temperature; hypothermia occurring at low (15° C) and hyperthermia at high (36° C) ambient temperatures. However, when the possibility of any peripheral action of noradrenaline escaping into the systemic circulation was prevented by prior subcutaneous injection of propranolol, significant hypothermia could be detected at temperatures as high as 32° C.4. The possibility that the effects of intraventricular noradrenaline could be due to complete abolition of central temperature regulation was further excluded by the occurrence of thermal salivation in all animals during experiments performed at 36° C.5. It is suggested that, in the mouse, the hypothermic actions of intraventricular noradrenaline are due to a central effect, while its hyperthermic effects at high ambient temperature are due to escape of noradrenaline into the peripheral circulation. The hypothermia could be the result of selective activation of central heat loss mechanisms.6. Intraventricular noradrenaline was without effect on brain plasma‐space although exposure to 100% oxygen caused a detectable fall.
Preliminary observations on the mechanical and electrical activity of the rat ureter
Authors: Tindall A. R. 
Published: December 2014

1. The electrical and mechanical activity have been recorded from the rat ureter in situ.2. The frequency of peristaltic contractions is usually about 25/min, and each peristalsis is preceded by electrical activity which normally travels from the renal end of the ureter towards the vesicular end. The electrical and mechanical activities are closely correlated.3. The velocity of propagation of the electrical activity is about 20 mm/sec.4. The normal electromyogram probably arises in the first 5 mm of the renal end of the ureter, and retrograde activity may arise from a similar region at the vesicular end of the ureter.5. A close arterial injection technique shows that the proximal end of the ureter behaves as if it possessed α‐receptors; the distal end behaves as if it had β‐receptors. This conclusion is discussed.
The actions of dibutyryl cyclic adenosine 3′,5′‐monophosphate and methyl xanthines on pancreatic exocrine secretion
Authors: Case R. M. , Scratcherd T. 
Published: December 2014

1. The effects of dibutyryl cyclic adenosine 3′,5′‐monophosphate (dibutyryl cyclic AMP) and theophylline have been tested in the stimulated and unstimulated perfused cat pancreas.2. Dibutyryl cyclic AMP (1·0 m
M) elicited the secretion of water and electrolytes, but not of enzymes, from this preparation. The composition of this secretion was the same as that secreted in response to secretin. This response could be slightly potentiated by theophylline.3. Theophylline, theobromine and caffeine all markedly potentiated submaximal secretin stimulation, the relative effectiveness of these methyl xanthines being the same as that observed in the inhibition of pure phosphodiesterase prepared from beef heart.4. At high concentration, theophylline had two effects: it was capable of initiating electrolyte and water secretion alone (whilst having only a very small stimulatory effect on enzyme secretion); it also had an inhibitory effect on secretion stimulated maximally by secretin.5. Thus it was easy to mimic the action of secretin, but not pancreozymin, using dibutyryl cyclic AMP and theophylline. This suggests that the action of secretin, but not that of pancreozymin, may be mediated through cyclic AMP. Further evidence is, however, needed before these conclusions can be made with confidence.