bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of catecholamines on the cholinergic neuromuscular transmission in fish red muscle
Authors: Hidaka T. , Kuriyama H. 
Published: December 2014

1. The effects of adrenaline and noradrenaline on neuromuscular transmission and the question of whether these catecholamines act on the presynaptic nerve terminal or on the post‐synaptic membrane were investigated using the fin muscles of the silver carp.2. Noradrenaline (10−8‐10−6 g/ml.) had no effect on membrane potential or input resistance of the membrane. In contrast, adrenaline (10−8‐10−6 g/ml.) hyperpolarized the membrane and increased the input resistance.3. Noradrenaline had no effect on the amplitude of the miniature junction potentials but caused them to become more frequent.4. Adrenaline enhanced the amplitude of the miniature junction potentials and slightly increased their frequency. These effects of adrenaline were partly due to the increased input resistance of the post‐synaptic membrane, and probably did not involve the presynaptic terminals.5. Both noradrenaline and adrenaline increased the amplitude and prolonged the falling phase of the excitatory junction potentials (e.j.p.s).6. Noradrenaline enhanced the amplitude and prolonged the duration of the extracellularly recorded excitatory junction current. No such effect was observed with adrenaline.7. Adrenaline but not noradrenaline enhanced the amplitudes of acetylcholine potentials evoked by iontophoretic application of acetylcholine.8. Noradrenaline and adrenaline had no effect on the compound action potentials of the nerve supplying the red muscle, recorded by the sucrose gap method.
Renal receptors evoking a spinal vasometer reflex
Authors: Beacham W. S. , Kunze Diana L. 
Published: December 2014

1. Certain afferent fibres in the renal nerves show an increased rate of discharge in response to small increases in renal vein pressure and to substantial increases of ureteral pressure. Such fibres enter the spinal cord largely through the upper lumbar dorsal roots.2. In spinal cats, stimuli exciting these afferent fibres evoke a reflex discharge in sympathetic nerves to the kidney and a fall in systemic arterial pressure. Change in flow or peripheral resistance, independent of arterial pressure, could not be demonstrated for the renal vascular bed. In spite of a lack of evidence for a renal vasomotor effect, the existence of the reflex fall in arterial pressure following excitation of receptors sensitive to venous pressure strongly implies that there is a form of circulatory regulation at the spinal cord level.
Cyanide stimulation of the systemic arterial chemoreceptors in foetal lambs
Authors: Dawes G. S. , Duncan Sheila L. B. , Lewis B. V. , Merlet Claudie L. , Owen-Thomas J. B. , Reeves J. T. 
Published: December 2014

1. In foetal lambs, delivered by Caesarean section under light chloralose anaesthesia, injection of sodium cyanide into the left atrium or ascending aorta caused a rise of arterial pressure and femoral vasoconstriction. The response to 0·77 mg/kg was barely present at 0·6 of term; by 0·8 of term there was a large response to one third of this dose.2. The cardiovascular response to cyanide injection into the left atrium or ascending aorta was diminished either by section of the vagi or by carotid denervation, and was abolished by cutting both sets of nerves.3. Injection of sodium cyanide into both common carotids simultaneously caused a substantial cardiovascular response and often a respiratory effort, abolished by carotid denervation, whereas injection into a single carotid rarely caused an effect.4. It is concluded that the carotid chemoreceptors in mature foetal lambs can be excited by a stimulus of sufficient intensity, even though they do not respond to moderate hypoxaemia.
5‐Hydroxytryptamine uptake and release in relation to aggregation of rabbit platelets
Authors: Baumgartner H. R. 
Published: December 2014

1. The aggregation of blood platelets was measured in vitro at different time intervals after the addition of 5‐hydroxytryptamine (5‐HT) or of reserpine to platelet‐rich plasma of untreated rabbits and of rabbits injected with reserpine and 5‐HT, i.e. while the platelets were taking up 5‐HT or releasing it under the influence of reserpine.2. When 5‐HT was added to stirred platelet‐rich plasma the platelets aggregated reversibly within 1 min. The velocity of aggregation increased with 5‐HT concentrations of 0·1–30 μ
M and decreased with higher concentrations.3. (—)‐Adrenaline, which alone did not produce aggregation, markedly accelerated the aggregation caused by 5‐HT. The acceleration was greatest when 5‐HT and adrenaline were added simultaneously.4. 5‐HT added to the platelet‐rich plasma in amounts that exceeded the 5‐HT capacity of the platelets progressively diminished the velocity of aggregation produced by 5‐HT plus adrenaline until aggregation was completely inhibited. Smaller amounts of 5‐HT produced a transient inhibition of aggregation.5. The aggregation of platelets from reserpinized rabbits was inhibited by less 5‐HT than the aggregation of platelets from normal rabbits.6. (—)‐Adrenaline aggregated platelets of untreated rabbits but not those of reserpinized rabbits or of rabbits injected with 5‐HT when reserpine was added in vitro 1‐30 min previously.7. Platelets obtained from rabbits treated first with reserpine and subsequently injected with 5‐HT were not aggregated by 5‐HT plus adrenaline. During incubation in vitro these platelets progressively recovered their aggregability but this recovery was delayed by the monoamine oxidase inhibitor Pargyline.8. Imipramine in concentrations which did not influence platelet aggregation by adenosine diphosphate (ADP) abolished aggregation produced by 5‐HT or by 5‐HT plus adrenaline.9. The inhibitory effect of adenosine on platelet aggregation was concentration‐dependent and similar whether aggregation was produced by ADP, 5‐HT or 5‐HT plus adrenaline.10. It is proposed that aggregation brought about by 5‐HT is connected with its active uptake into the platelets and is caused by ADP formed from ATP during the active uptake of the amine. When 5‐HT is no longer actively taken up, it also ceases to cause or to potentiate aggregation.
Permeability of lung capillaries to macromolecules in foetal and new‐born lambs and sheep
Authors: Boyd R. D. H. , Hill June R. , Humphreys P. W. , Normand I. C. S. , Reynolds E. O. R. , Strang L. B. 
Published: December 2014

1. The permeability of lung capillaries to macromolecules was investigated in immature and mature foetal lambs, new‐born lambs and young sheep. The placental circulation of the foetal animals was maintained intact after delivery by Caesarian section. New‐born lambs and sheep were mechanically ventilated. Samples of plasma and lymph that had drained from the lung via the thoracic duct were collected over a period of 1–5 hr.2. The proteins in plasma and lymph samples were separated by fractionation on columns of Sephadex G‐200. Plasma yielded three peaks of protein concentration. The Kav value of each peak was determined, and, by calibrating the columns with known proteins, the mean radius of equivalent sphere (a) of the proteins in peak I was shown to be similar to that of fibrinogen ≥ 110 Å, peak II to γ‐globulin ≈ 54 Å and peak III to albumin ≈ 34 Å. Lung lymph contained the same three constituent peaks as plasma but in lower concentration. In all four groups mean lymph/plasma concentration (L/P) ratio was significantly different for each of the three peaks, being lowest for the largest molecules (peak I) and highest for the smallest (peak III).3. In five mature foetal lambs polydisperse polyvinylpyrrolidone labelled with 125I ([125I]PVP) was injected
I.V. early in the experiment: count rates in fractionated samples showed for plasma a continuous decline with time after injection, and for lung lymph an increase to a maximum then a decline. Steady‐state L/P ratios for eleven fractions of PVP of differing molecular size ranging from 110 to 17 Å were derived by compartmental analysis. For a given molecular size PVP L/P ratios were similar to protein L/P values.4. The regression of PVP L/P ratio on Kav was linear (correlation coefficient r = 0·99), and the slope of the regression of protein L/P ratio on Kav was significantly steeper for new‐born lambs than for mature foetuses (P < 0·025) and sheep (P < 0·005), and steeper for immature foetuses than sheep (P < 0·01).5. PVP and protein L/P ratios (mature foetuses) plotted against a showed a sigmoid relation with agreement between the two sets of L/P ratios. The goodness of fit between our experimental results and Landis & Pappenheimer's (1963) capillary pore theory (eqn. (1)) was examined: L/P ratios for the larger molecules (≥ 75 Å) appeared to be too high. By recalculating ratios on the assumption that the largest molecules (110 Å) escape unrestricted from the capillary via leaks, the discrepancy disappears.6. Values for pore radius (r), and pore area per unit path length (A/Δx) have been calculated for each of the four groups; r ranged from 90 to 150 Å, A/Δx from 3·3 to 0·2 cm × 103.kg−1. In new‐born lambs the value of r was significantly smaller, and A/Δx larger than that of any other group. The inferences to be drawn from these results are discussed.
The projection of splanchnic afferents on the cerebellum of the cat
Authors: Newman P. P. , Paul D. H. 
Published: December 2014

1. The projections of the ipsilateral and contralateral splanchnic nerves on the cerebellum were studied in cats under sodium thiopentone anaesthesia.2. The splanchnic nerves were electrically stimulated. Evoked potentials and single unit discharges were recorded by means of 2·5
M‐NaCl‐filled glass micropipettes. A responsive region was found in the intermediate cortex of lobules Vb to f of the anterior lobe.3. The Aγδ fibres of the splanchnic nerve had a bilateral cerebellar representation. The Aβ fibres were represented only on the ipsilateral side.4. At the level of the upper cervical spinal cord, fibres from the ipsilateral splanchnic nerve were conveyed in both the dorsal and lateral funiculi; fibres from the contralateral nerve were restricted to the ipsilateral lateral funiculus.5. On the basis of the characteristic potential fields generated in the cerebellar cortex, it is concluded that the majority of the splanchnic afferents studied terminate in the cerebellum as climbing fibres. A few responses of short latency may have been due to a mossy fibre input.6. In interaction experiments, a conditioning stimulus to one splanchnic nerve depressed the response to stimulation of the other nerve for up to 80–100 msec, the effect being most pronounced at 40–50 msec. During this period, spontaneous activity of the cerebellar unit was also suppressed.7. The organization of the splanchnic pathways to the cerebellum and their terminal connexions are discussed.
Contribution of the diaphragm and the other inspiratory muscles to different levels of tidal volume and static inspiratory effort in the rabbit
Authors: Mognoni P. , Saibene F. , Sant'Ambrogio G. 
Published: December 2014

1. The contribution of the diaphragm and that of the other inspiratory muscles at different levels of tidal volume and during static inspiratory efforts of various strength has been studied in supine rabbits by blocking phrenic conduction with an electrotonic current. The rabbits were lightly anaesthetized with urethane and pentobarbitone.2. The volume displaced by the extradiaphragmatic muscles (VtEDM) in vagotomized rabbits increases linearly with the tidal volume (Vt), according to the function VtEDM = − 3·27 + 0·32 Vt. The relative contribution of extradiaphragmatic muscles (VtEDM/Vt × 100) for resting ventilation is 12% and becomes ca. 25% for the maximum Vt value attained during re‐breathing.3. When the vagi are left intact, the VtEDM is always higher because of the compensatory hyperactivity of the extradiaphragmatic muscles due to Hering—Breuer reflexes during the phrenic block.4. The pressure exerted by the extradiaphragmatic muscles, during inspiratory efforts with closed airways, increases linearly with the strength of the effort, without any difference between intact and vagotomized rabbits. The relationship between the pressure exerted by the extradiaphragmatic muscles (PEDM) and the pressure exerted by all the inspiratory muscles (P) is expressed by the function PEDM = − 3·29 + 0·38P.5. These results indicate that the diaphragm is the main inspiratory muscle at all levels of inspiratory activity.
The relation between sweat rate and weight loss when sweat is dripping off the body
Authors: Brebner D. F. , Kerslake D. McK. 
Published: December 2014

1. The relation between the rate of sweat production, Ṡ, and the rate of weight loss, Ẇ, has been examined under conditions in which the rate of evaporation was small.2. Ṡ could be found from Ẇ provided that a film of liquid was maintained over the skin surface. This could be achieved initially by immersing the subject in water containing detergent. Thereafter the film was maintained so long as the rate of weight loss exceeded about 10 g/min.3. When the rate of weight loss was changing and the rate of evaporation was constant, Ṡ could be calculated as Ẇ + 2·5 Ẅ.4. When the subject was constantly sprayed with water while being weighed, the correction for Ẅ became negligible. In this case there was no lower limit to the sweat rate which could be measured, but spraying considerably reduced the accuracy of the measurement.5. The output of sweat from a ventilated capsule on the forearm correlated well with estimates of central sweating drive based on weight measurements corrected for hidromeiosis.
The interaction of presynaptic polarization with calcium and magnesium in modifying spontaneous transmitter release from mammalian motor nerve terminals
Authors: Landau E. M. 
Published: December 2014

1. The relationship between motor terminal polarization and miniature end‐plate potential (m.e.p.p.) frequency was examined in the presence of various Ca, Mg and K concentrations ([Ca], [Mg] and [K]) and also at modified bathing osmolarity levels. The polarization changes were obtained with ‘electrotonic’ and ‘focal’ polarizing currents and with rapid changes in bathing [K].2. M.e.p.p. frequency increased exponentially with electrotonic depolarizing currents, but failed to decrease similarly with hyperpolarizing currents. An increase in bathing [K] to 15 mM increased the sensitivity of the terminals to presynaptic hyperpolarization.3. The slope, on semilogarithmic coordinates, of the function relating m.e.p.p. frequency to electrotonic polarizing currents (the release‐current function) was unchanged when bathing [Ca] was raised from 2 to 8 mM. When [Ca] was reduced to 0·5 mM the slope of this function was reduced initially but eventually approached the same slope as in control [Ca]. A similar effect was also found in the presence of 15 mM‐KCl.4. The relationship between m.e.p.p. frequency and log [K], at various [Ca], resembled the relationships between m.e.p.p. frequency and presynaptic polarizing currents.5. An increase in bathing [Mg] or osmolarity had a similar effect to a reduction of [Ca].6. Tetrodotoxin (TTX) at a concentration of 10−6 g/ml. was found to reduce m.e.p.p. frequency, at various [K], by a constant fraction of about 30%.7. In some of the junctions ‘anodic break‐down’ was observed. An examination of this phenomenon with focal polarizing currents disclosed an unusual type of ‘anodic break‐down’, with rapid ‘on’ and ‘off’ responses. This phenomenon may indicate that release depends on the influx of positively charged particles into the nerve terminals.8. It is concluded that nerve terminal depolarization accelerates exponentially the activity of a membrane component bearing three Ca molecules, the rate of acceleration being independent of bathing [Ca].
Dorsal column projection of fibres from the cat knee joint
Authors: Burgess P. R. , Clark F. J. 
Published: December 2014

1. Stimulation of the cervical dorsal columns excited an average of nine knee joint fibres in the cat posterior articular nerve, eleven fibres in the cat medial articular nerve and thirteen fibres in the monkey posterior articular nerve.2. Joint fibres projecting to cervical levels were shown to be rapidly adapting by recording with micro‐electrodes from single fibres in intact cat posterior articular nerves. The numerous slowly adapting fibres could not be antidromically excited from the cervical dorsal columns.3. Several control experiments suggested that the antidromic stimulation method accurately defined the dorsal column projection of joint fibres.
The activity of lung irritant receptors during pneumothorax, hyperpnoea and pulmonary vascular congestion
Authors: Sellick Hilary , Widdicombe J. G. 
Published: December 2014

1. The activity of lung irritant receptors during pneumothorax, hyperpnoea and pulmonary congestion has been studied by recording from single vagal nerve fibres from the receptors in rabbits.2. The receptors were stimulated during induction and during removal of pneumothorax.3. Pneumothorax caused a greater depression of minute volume in bilaterally vagotomized rabbits, compared with those with intact vagus nerves.4. Hyperpnoea due to breathing through an added dead space increased the discharge of the receptors. Experiments on paralysed and artificially ventilated rabbits showed that this was not a direct action of the asphyxial changes in blood gas tensions.5. Pulmonary congestion, induced by inflating a balloon in the left atrium, stimulated the receptors in paralysed artificially ventilated rabbits.6. The evidence that the receptors cause vagal reflex hyperpnoea and bronchoconstriction is discussed, together with their role in the reflex ventilatory and bronchomotor changes in the conditions studied.
Hind leg ataxia of cervical origin and cervico‐lumbar spinal interactions with a supratentorial pathway
Authors: Abrahams V. C. , Falchetto S. 
Published: December 2014

1. Unilateral section of the nerves to an extensor muscle of the head, biventer cervicis, leads to an ataxia of the hind legs in cats.2. In chloralose anaesthetized cats, shocks to the central end of the cut biventer cervicis muscle nerves leads to direct discharges over lumbosacral ventral roots, to a facilitation of monosynaptic reflexes in flexor and extensor muscles and to a prolonged inhibition of spino‐bulbo‐spinal reflexes. Such effects are not unique, but follow stimulation of skin and muscle nerves of the forepaw.3. Supratentorial pathways are involved in descending spinal interactions in the chloralose anaesthetized cat, but are more critical for interactions taking origin in biventer cervicis nerve than in forepaw nerves.4. In non‐anaesthetized spinal cats showing interactions from forepaw nerves, no interactions could be found taking origin in biventer cervicis nerves. Descending interactions from forepaw nerves could be reduced or abolished by anaesthetic doses of chloralose.5. The rich pathway from biventer cervicis nerve to the superior colliculus does not appear to be involved in the descending interactions reported here as neither stimulation nor ablation of the superior colliculi has any effect on descending interactions.
Gustatory impulse discharges in response to saccharin in rats and hamsters
Authors: Ogawa H. , Sato M. , Yamashita S. 
Published: December 2014

1. Impulse discharges produced by saccharin sodium as well as four basic gustatory stimuli were recorded in chorda tympani fibres of rats and hamsters.2. Units predominantly sensitive to NaCl showed a concentration—response magnitude curve for saccharin sodium similar in shape to that for NaCl but smaller in magnitude. Units of this category did not respond to 0·01
M saccharin buffered with tris(hydroxymethyl)aminomethane. Response to saccharin sodium in these units are considered to result from stimulation of receptor molecules by Na ions.3. Units predominantly sensitive to sucrose showed a concentration—response magnitude curve for saccharin sodium with a maximum magnitude at about 0·01–0·1
M. Impulse discharges produced by sucrose and saccharin sodium showed rhythmic burst‐like firing. Units of this category responded well to 0·01
M saccharin. Responses to saccharin sodium in these units are attributed to the reaction between saccharin molecules and receptor sites.4. The optimum concentration at which a greatest response magnitude was found varies from one unit to the other and is inversely related to sucrose sensitivity, units highly sensitive to sucrose showing a low optimal concentration. Presence of the optimum concentration is explained by a mechanism known as the non‐competitive auto‐inhibition.5. Off‐responses were observed in units predominantly sensitive to sucrose when 0·03–1
M saccharin sodium applied to the tongue was rinsed with water.6. Neural information for saccharin sodium is described quantitatively in relation to that for four basic gustatory stimuli.
Cable properties of external intercostal muscle fibres from myotonic and nonmyotonic goats
Authors: Bryant S. H. 
Published: December 2014

1. In preparations of about 200 fibres each from thirty‐nine biopsies of external intercostal muscle taken from nine myotonic and six nonmyotonic goats, cable properties were determined at 38° C for individual fibres with a pair of intracellular micro‐electrodes.2. In each preparation the mean fibre dimensions, determined histologically and corrected for shrinkage, were used to calculate the mean membrane resistance, Rm, fibre capacitance, Ct, and myoplasmic resistivity, Ri. In the 124 nonmyotonic fibres the mean values were: Rm, 1897 Ω.cm2, Ct, 4·1 μF/cm2, and Ri, 112 Ω.cm. In 151 myotonic fibres Rm was 5589 Ω.cm2, Ct, 4·4 μF/cm2, and Ri, 103 Ω.cm.3. Conductance of the fibre core times unit length increased with cross‐sectional area, and fibre capacitance per unit length increased with perimeter. There was little correlation of membrane resistance per unit length of fibre with either fibre perimeter or resting potential.4. The principal abnormality of cable properties in the myotonic fibre is its threefold higher membrane resistance, which accounts for its decreased electrical current rheobase.
Change of tubular reabsorption of sodium and water after denervation
Authors: Bonjour Jean-Philippe , Churchill Paul C. , Malvin Richard L. 
Published: December 2014

1. Renal function was compared in dogs before and after denervation, with normal or reduced glomerular filtration rate (GFR). GFR was reduced by one of two means, aortic clamping or injection of plastic microspheres into one renal artery.2. The data showed that the tubular rejection fraction of denervated kidneys increased at a time when the same value for the control kidney decreased, indicating that denervation diuresis is not simply a result of increased filtered load of Na and water.3. Changes in excretion after aortic clamping are not due solely to reduced filtered load. A reduction in renal blood pressure itself appears to have a direct effect on Na transport since Na excretion was significantly decreased before there were any changes in GFR, renal plasma flow and urine volume.4. When GFR in a denervated kidney was reduced by microsphere injection it was demonstrated that a significant natriuresis (UNa V) and diuresis (V) occurred when. GFR was reduced by as much as 40%.5. These experiments support the hypothesis that denervation diuresis does not result solely from increased filtered load, but entails altered Na transport.