bluuebunny/crossref_metadata_2025_split huggingface dataset:
The mechanical properties and heat production of chicken latissimus dorsi muscles during tetanic contractions
Authors: Canfield S. P. 
Published: December 2014

1. A study has been made of the mechanical properties and heat production of chicken anterior (ALD) and posterior (PLD) latissimus dorsi muscles during contractions at 20 °C.2. There is a difference between these two muscles in the time course of the isometric response. The PLD reaches maximum tetanic tension 10 times faster and relaxes 8 times faster than ALD. The ratio of heat rate to isometric tension (heat rate/tension × length) for PLD is 7–8 times larger than for ALD.3. ALD maintains substantial isometric tension for more than 2 min of stimulation. In PLD tetanic tension begins to fall after only 1 sec.4. The ALD muscle does not show the ‘activation’ heat seen at the start of contraction with frog and toad muscle but this may be present in PLD.5. There is a range of stimulation frequencies for both muscles over which the fused tetanic tension increases with stimulation frequency.6. The tension—length curve of ALD has a pronounced plateau and is broader than that of PLD.7. The normalized force—velocity relations for the two muscles are similar and may be fitted by Hill's equation with a value of a/P0 = 0·15–0·16. The maximum velocity of unloaded shortening of PLD is 4‐5 times that of ALD.8. Preliminary experiments indicate that the resting heat rate of both muscles is 4 times greater than that of frog muscle at the same temperature. The recovery heat rate of ALD is similar to that of frog.
Mechanisms relating gastric acid secretion and mucosal blood flow during gastrin and histamine stimulation
Authors: Reed J. D. , Smy J. R. 
Published: December 2014

1. Gastric mucosal blood flow (MBF) and gastric acid secretion have been compared and related during the infusion of a wide dose range of gastrin extracts, pentapeptide (Peptavlon, I.C.I. 50123) and histamine.2. Constancy of increase in mucosal blood flow relative to H+ secretion was obtained with gastrin stimulation, whereas histamine stimulation produced higher ratios of mucosal blood flow to H+ secretion, and these ratios declined as each experiment continued.3. The importance of considering only the increase in mucosal blood flow in relation to acid secreted is demonstrated.4. It is concluded that the differences shown in the ΔMBF/ΔH+ with histamine and gastrin stimulation provide further evidence that the amidopyrine clearance technique measures gastric mucosal blood flow.
The activity of identified supraoptic neurones and their response to acetylcholine applied by iontophoresis
Authors: Dreifuss J. J. , Kelly J. S. 
Published: December 2014

1. In urethane/pentobarbitone anaesthetized male rats, the hypothalamus and pituitary stalk were exposed by a transpharyngeal approach. Cells recorded with glass micro‐electrodes from the ventral hypothalamus near the bifurcation of the internal carotid artery were identified as supraoptic neurones only when their antidromic action potential evoked at constant latency by stimulation of the pituitary stalk was cancelled by collision with a spontaneously occurring action potential.2. More than 80% of the identified cells were spontaneously active. The frequency of firing was often slow (under 1 Hz) and rather irregular. More than half the cells, however, had a more distinctive firing pattern which recurred every 1‐3 min and consisted of a period of low or absent activity alternating with periods of quite marked discharge which occasionally exceeded 20 Hz. This periodicity was retained when the over‐all activity was enhanced by an intracarotid injection of 0·2 ml. 5% (w/v) NaCl.3. Of fifty‐two cells tested, thirty‐six were excited by acetylcholine applied by iontophoresis from a multibarrelled micropipette with average ejection currents of 35 ± 5 nA (
S.D. of thirty‐six observations). Ten of these cells were also excited by nicotine applied with similar currents.
Compensatory hypertrophy of the contralateral kidney after unilateral ureteral ligation
Authors: Dicker S. E. , Shirley D. G. 
Published: December 2014

1. The ligation of one ureter is accompanied by compensatory hypertrophy of the contralateral kidney.2. The rate of growth of the contralateral kidney after ligation of the opposite ureter is similar to that observed after unilateral nephrectomy.3. Ligation of one ureter produced ipsilateral hydronephrosis.4. The development of hydronephrosis was accompanied by a marked increase of DNA, suggesting hyperplasia, and of the rate of anaerobic glycolysis, while the rate of oxygen uptake decreased, especially in the cortex.5. During compensatory hypertrophy of the contralateral kidney, after ligation of the opposite ureter, there were increases of RNA/DNA ratios and of oxygen uptake, especially marked in the cortex, and in every respect similar to those observed after unilateral nephrectomy.6. Ligation of one ureter resulted in an increase of glomerular filtration rate of the contralateral kidney similar to that observed after unilateral nephrectomy.7. The mechanisms of contralateral renal hypertrophy after ligation of one ureter and after unilateral nephrectomy are discussed. It is suggested that in both cases the prime mover to compensatory hypertrophy is the increase of glomerular filtration rate.
The effect of angiotensin, noradrenaline and vasopressin on blood flow distribution in the rat kidney
Authors: Finberg J. P. M. , Peart W. S. 
Published: December 2014

1. The effect of val5‐angiotensin II amide, noradrenaline and vasopressin, on kidney volume and intrarenal distribution of carbon particles and thioflavine S was examined in the rat.2. Angiotensin produced a dose‐dependent shrinkage of the kidney coinciding with the rise in systemic blood pressure. Noradrenaline and vasopressin, however, produced reduction in kidney volume only in much higher doses than were necessary to produce a pressor effect.3. An intravenous infusion of angiotensin sufficient to produce a diuretic response resulted in a striking increase in glomerular content of injected carbon particles, and a marked reduction in filling of the capillary plexuses of the subcortex and outer medulla. The reduction in outer medullary filling was also observed using the thioflavine S technique.4. Noradrenaline infused in amounts sufficient to produce diuresis, aortic constriction above the kidney and vasopressin injection produced no measurable change in carbon particle distribution.5. The reduction in capillary blood flow produced by angiotensin may result in impaired tubular reabsorptive capacity by reducing peritubular removal of reabsorbate, or by reducing oxygen availability. Thus the vasoconstrictor effects of angiotensin may explain its diuretic action.
Pharmacological properties, cholinesterase activity and anatomy of nerve—muscle junctions in vagus‐innervated frog sartorius
Authors: Landmesser Lynn 
Published: December 2014

1. The pharmacological properties of the nerve—muscle junctions of vagus‐innervated frog sartorius muscles were investigated. Vagus‐evoked junctional potentials were ten times more sensitive to hexamethonium than were control end‐plate potentials from muscles re‐innervated with sartorius nerve. Hexamethonium did not affect passive electrical muscle membrane properties or quantal content. The sensitivity of vagus junctions to
D‐tubocurarine (dTC) did not differ from the controls.2. The amplitude and time course of vagus‐evoked junctional potentials were not affected by eserine or neostigmine. Furthermore, histologically detectable acetylcholinesterase activity was not demonstrable at vagus‐muscle junctions.3. The ultrastructure of vagus‐innervated muscle fibres was normal in appearance indicating that the vagus was capable of structurally maintaining the muscle fibres.4. Junctional contacts were made by varicosities of unmyelinated vagal fibres. Although such varicose vagal fibres ran along the muscle fibres for long distances, they seemed to make synaptic contacts primarily at old end‐plate regions, as deduced from persisting junctional folds.5. It is concluded that at least several ‘trophic’ factors are probably involved in the different effects of the vagus nerve on the sartorius muscle.
Ionic differences between somatic and axonal action potentials in snail giant neurones
Authors: Wald Flora 
Published: December 2014

1. The ionic requirements of the somatic and axonal action potentials of ‘H’ neurones of the snail Cryptomphallus aspersa were studied using intracellular micro‐electrodes.2. The overshoot of the somatic action potential increased by 10 mV for a tenfold increase in [Ca2+]o. In calcium‐free media the action potential decreased gradually to values of 50 to 90% of the control and they could be completely eliminated with 2 m
M‐EGTA. The maximum rate of rise also varied with [Ca2+]o.3. After 2 hr in sodium‐free solution the somatic action potential decreased 6% in overshoot and 24% in rate of rise.4. The somatic action potential was not affected by TTX, 5 × 10−6 g/ml. Procaine, 18 m
M, reduced its rate of rise but did not eliminate it whereas 30 m
M‐CoCl2 did.5. The size of the axonal action potential increased with increased [Na+]o, but decreased with an increase in [Ca2+]o.6. Procaine, 18 m
M, abolished the axonal action potential whereas it was not affected by TTX, 5 × 10−6 g/ml., nor, usually, by 30 m
M‐CoCl2.7. The results obtained by studying the compound action potential of the nerves were similar to those from axonal action potentials.8. The possibility that the somatic action potential is mainly calcium dependent while the axonal action potential is mainly produced by sodium is discussed.
The sensitivity of the hepatic glycogenolytic mechanism to stimulation of the splanchnic nerves
Authors: Edwards A. V. 
Published: December 2014

1. The sensitivity of the hepatic glycogenolytic mechanism to splanchnic nerve stimulation at relatively low frequencies has been investigated in adrenalectomized calves, dogs and cats.2. In young calves the hyperglycaemic response to splanchnic nerve stimulation at 1·0 c/s for 5 min increased steadily during the first 2 weeks after birth.3. The hyperglycaemic response to splanchnic nerve stimulation for 5 min was directly related to frequency of stimulation within the range 0·5–4·0 c/s in calves tested 2‐5 weeks after birth. Pronounced rises in plasma glucose concentration also occurred in calves of this age in response to maximal stimulation (20 c/s) for shorter periods (30 sec) whereas occlusion of the portal vein for the same period produced no comparable effect.4. The effects of splanchnic nerve stimulation for prolonged periods were also investigated in 2‐ to 5‐week‐old calves. Under these conditions increased concentrations of glucose in the plasma were maintained for periods of up to 90 min and fell towards the initial values when stimulation was discontinued.5. Prolonged stimulation of the peripheral ends of both splanchnic nerves at either 2·0 or 4·0 c/s produced a transient reversal of hypoglycaemia in calves pretreated with large doses of insulin; both the extent and duration of these responses were related to frequency of stimulation.6. The hyperglycaemic response to bilateral splanchnic nerve stimulation was directly related to frequency of stimulation within the range 0·5–4·0 c/s in adrenalectomized dogs. Comparable responses were obtained in adrenalectomized cats in response to stimulation at 2·0 c/s, but stimulation at 1·0 c/s produced no rise in mean plasma glucose concentration in these animals.7. The sensitivity of the hepatic glycogenolytic mechanism has been assessed in relation to the associated changes in haematocrit and mean aortic blood pressure under the same conditions.8. The results of these experiments support the contention that tonic changes in sympathetic efferent activity are associated with variations in the rate at which glucose is released from the liver under physiological conditions.
Image quality of the cat eye measured during retinal ganglion cell experiments
Authors: Bonds A. B. , Enroth-Cugell Christina , Pinto L. H. 
Published: December 2014

1. The modulation transfer function (MTF) of the dioptrics of fifteen cat eyes was determined. The aerial image, formed by the eye of a standard object (a 0·5–1·0° annulus), was photographed. The transmission of the film negative was measured with a scanning microdensitometer to yield the light distribution within the aerial image. Correcting for the double passage, this experimentally determined light distribution and the known object light distribution were used to obtain the MTF, applying Fourier methods. Each MTF was used to calculate the light distribution within the retinal image of stimuli of various geometry used in experiments on retinal ganglion cells in the same eye.2. When the eye was equipped with an artificial pupil of the same size as that used in the neurophysiological experiments (4·0–4·8 mm diam.) the MTF had fallen to 0·5 at 2·43 c/deg. When the pupil was removed the MTF had fallen to 0·5 at a much lower spatial frequency (1·0 c/deg). This shows that even when one uses an artificial pupil too large to provide optimal image quality there is a vast improvement over using no pupil.3. These image quality measurements were prompted by the need to know the actual stimulus image in experiments on the functional organization of the receptive field, a need exemplified in this paper by a few specific physiological results. The full neurophysiological results appear in the next two papers.
Properties of the surround response mechanism of cat retinal ganglion cells and centre‐surround interaction
Authors: Enroth-Cugell Christina , Pinto L. H. 
Published: December 2014

1. The properties of the surround response mechanism of on‐centre cells and its interaction with the centre mechanism were studied by recording from single optic tract fibres. In many of the experiments the spatial distribution of the light within the retinal image of the stimuli was measured.2. Pure surround responses of on‐centre cells were isolated using a centrally located steady light which selectively desensitized (adapted) the centre mechanism. This permitted a peripheral flashing stimulus whose luminance varied over a range as great as 1·38 log units to elicit surround responses which, for any given cell, were of invariant shape. The rate of decay of the firing frequency of the spike burst at ‘off’ varied from cell to cell. The general characteristics of such pure surround responses to squarewave stimuli were described. The plot of the magnitude of pure responses against stimulus luminance, at constant background conditions, was curvilinear.3. The pure surround response of two off‐centre cells was isolated; it was similar in shape to the pure centre response of on‐centre cells.4. Interaction of centre and surround mechanisms of on‐centre cells was studied by eliciting a pure central and a pure surround response from the same cell. The electronically obtained algebraic sum of these two pure responses equalled the mixed response of the ganglion cell to simultaneous presentation of the stimuli which evoked the pure responses when presented singly. This is probably best explained by algebraic summation of centre and surround inputs.5. The pure surround response from two cells to a fixed flashing stimulus was attenuated by a steady field adapting light, both when this was superimposed upon the stimulus and when not superimposed. In the latter case, (i) when the spatial separation between the flashing stimulus and the adapting light was at a minimum, less than 10% of the adapting flux fell inside the boundaries of the stimulating flux, and (ii) the response was attenuated also if the adapting light was in the geometric centre of the receptive field. These results indicate that the adaptation pool of the surround mechanism extends to the central portions of the receptive field.6. Nearly half the cells tested did not yield pure surround responses. This was probably due to differences, within the ganglion cell population, (i) of the spatial distribution of the ratio of centre to surround signal sensitivity and (ii) of differences in the ratio of centre to surround adaptivity in the receptive field middle. It was not due to excess adaptive flux falling outside the region of maximal centre mechanism adaptivity, nor due to excess stimulus flux falling inside the region of maximal signal sensitivity.
Activation of the electrogenic sodium pump in guinea‐pig auricles by internal sodium ions
Authors: Glitsch H. G. 
Published: December 2014

1. The effect of various intracellular Na concentrations ([Na]i) on the membrane potential after hypothermia was studied in guinea‐pig auricles.2. For varying [Na]i, the atria were cooled for 4 hr at 4‐6° C in a K‐poor solution with different concentrations of NaCl. The auricles were rewarmed in normal Tyrode solution at 35° C.3. Extracellular space (ECS), intracellular Na and K concentrations ([Na]i and [K]i) and membrane potential of the atria were measured before and after hypothermia.4. The ECS, measured as inulin space, amounted to 350 ml./kg wet wt. at 35° C and to 300 ml./kg wet wt. at 4‐6° C.5. [K]i decreased during cooling and increased during rewarming the auricles. [Na]i increased during hypothermia in bathing fluids containing NaCl, but decreased in NaCl‐ and Na‐free solutions. At the beginning of rewarming a net Na transport occurred from cells with high [Na]i, while a net Na uptake took place in atria with low [Na]i.6. At the same time, the membrane potential of auricles with increased [Na]i hyperpolarized beyond the steady‐state value recorded at the end of rewarming, or even beyond the calculated K+ equilibrium potential (EK). Afterwards, the hyperpolarization levelled off, while the EK values increased further. The membrane potential of atria with decreased [Na]i showed no transitory hyperpolarization during rewarming.7. The hyperpolarization beyond the steady‐state value of membrane potential in rewarmed auricles was significantly correlated to the active Na efflux.8. From these results it is concluded that the membrane potential of guinea‐pig atria after hypothermia is affected by an active, electrogenic Na pump activated by intracellular Na ions.
Energetics of activation in frog and toad muscle
Authors: Smith I. C. H. 
Published: December 2014

1. If activation heat reflects the operation of the calcium pump it should be independent of actomyosin activity. The semitendinosus preparation affords a technique for removing actomyosin activity since the muscle can be stretched till there is almost no overlap between the filaments.2. Heat production, H, in twitches and tetani of stretched muscle fits the relation H = A+M.P/Pot where P/Pot is the fraction of the optimal tension remaining at the stretched length and A and M are assumed to be the activation dependent and actomyosin dependent heat components.3. For twitches the A component is early and fast and constitutes 0·26 (
S.D. 0·09) of the heat production at normal muscle lengths. Its time course is similar in both frog and toad muscle although both M and P are twofold slower in toad muscle. High concentrations of CO2 slow only M and Pot. The A component is associated with a normal recovery heat.4. The twitch‐tetanus tension ratio, after correction for the extra shortening that occurs during a tetanus, does not vary with the degree of muscle stretch: it is thus probable that twitch activation does not vary with muscle stretch.5. Moderately hypertonic Ringer solution reduces M and Pot but not A, but strongly hypertonic solution also reduces A. Zn2+, No3− and second shock potentiation of a twitch increase A, M and Pot in proportion to each other.
Effect of chemical sympathectomy on the content of acetylcholine, choline and choline acetyltransferase activity in the cat spleen and iris
Authors: Consolo S. , Garattini S. , Ladinsky H. , Thoenen H. 
Published: December 2014

1. Acetylcholine and choline were measured in the spleens and irides of normal and 6‐hydroxydopamine‐treated cats. In addition, choline acetyltransferase activity was measured in the spleens.2. No acetylcholine or choline acetyltransferase activity were found in spleens of normal or treated cats. The choline content of normal spleens was 12·4 ± 1·5 μg/g wet wt. (mean ±
S.E. of mean), which was not significantly altered by chemical sympathectomy.3. The acetylcholine and choline contents of the cat iris were 3·0 ± 0·3 μg/g wet wt. and 7·7 ± 0·9 μg/g wet wt., respectively. There was no difference in acetylcholine and choline concentrations between left and right or normal and sympathectomized irides.4. These results are discussed in relation to the question of a cholinergic link in post‐ganglionic sympathetic transmission.
Relationships between blood flow and secretion in the isolated perfused canine pancreas
Authors: Augier Danièle , Boucard J. P. , Pascal J. P. , Ribet A. , Vaysse Nicole 
Published: December 2014

1. Stimulation by a continuous intra‐arterial infusion of secretin caused a marked vasodilatation in the pancreato‐duodenal preparation or in the isolated pancreas perfused with whole heparinized blood. There was no difference in the vasomotor effects of two unequally purified preparations of secretin. The fact that the vasodilatation was still observed when the duodenum was removed proved that the haemodynamic effect of secretin was initiated in the pancreas itself.2. The secretory response of the pancreas to a given dose of secretin was larger when the blood pressure was kept constant by increasing the blood flow than when the blood pressure was allowed to fall by maintaining the blood flow at a fixed value. It is concluded that the vasodilatation plays a role in the functional regulation of the pancreatic response to secretin.3. The correlation between blood flow and arterial pressure on the one hand, and the secretory response to secretin on the other, was not mediated by the control of respiration since there was no variation in oxygen uptake in response to a variation in the blood flow. This correlation was still observed when the venous blood was discarded and therefore could not be explained by variations in the rate of recirculation of secretin. It was observed too in experiments where the duodenum was removed, the pancreas alone being introduced into the perfusion apparatus, which indicated that this effect was not mediated by a control of the release of secretin by the duodenum.
The effect of diameter on the electrical constants of frog skeletal muscle fibres
Authors: Hodgkin A. L. , Nakajima S. 
Published: December 2014

1. Electrical constants were determined on isolated single fibres or on fibres from bundles from frog's twitch muscles by analysing the low frequency cable properties.2. The sarcoplasmic conductivity (Gi) was 5·9 mmho/cm at 20° C, and its temperature coefficient (Q10) was 1·37.3. The Q10 of the membrane conductance (GM) was 1·49, and that of the membrane capacity (CM) was 1·02.4. CM increases with diameter (D) in an approximately linear manner: the values were 4·6 μF/cm2 at D = 50 μ, and 8·5 μF/cm2 at D = 130 μ.5. GM also increases with diameter, being 0·21 mmho/cm2 at D = 50 μ and 0·37 mmho/cm2 at D = 130 μ.6. These results suggest that the transverse tubular system contributes substantially to the values of low frequency capacity and conductance measured at the surface membrane.
Proximal negative response in the pigeon retina
Authors: Holden A. L. 
Published: December 2014

1. The proximal negative response (PNR) of the inner plexiform layer of the pigeon retina was recorded intraretinally.2. The PNR can be distinguished from the local b‐wave by its area dependence, and its depth profile in the retina.3. The ‘on’ and ‘off’ transients of the PNR have differing depth profiles in the retina: the ‘on’ transient is distributed vitreal to the ‘off’, and both are distributed vitreal to the b‐wave.4. As spot diameter is increased, so the amplitude of the PNR decreases, and the threshold rises.5. Ganglion cells fire at ‘on’ and ‘off’ during the PNR and like the PNR, are suppressed as spot size is increased.