bluuebunny/crossref_metadata_2025_split huggingface dataset:
An analysis of the inhibition of phrenic motoneurones which occurs on stimulation of some cranial nerve afferents
Authors: Biscoe T. J. , Sampson S. R. 
Published: December 2014

1. Inhibition and excitation of spontaneous phrenic nerve discharges in response to stimulation of the sinus, glossopharyngeal, aortic and superior laryngeal (SLN) nerves has been investigated in cats.2. The inhibition, in response to a single shock, had a latency of 5‐10 msec and lasted for 20–40 msec; the response to SLN stimulation was the most prolonged.3. Excitation of phrenic motoneurones also occurred and was seen either before or after the end of the inhibition of the inspiratory burst and sometimes also during expiration.4. Intravenous strychnine blocked the inhibition.5. Intracellular recording from phrenic motoneurones showed that hyperpolarization was evoked by each nerve during the central phrenic depolarizing potential (CPDP) but only rarely in the interval between these potentials.6. When the CPDP was suppressed, hyperpolarization could sometimes be evoked.7. There were no changes in amplitude or time course of hyperpolarization during the passage of current through the cell membrane. No change in membrane conductance could be shown by passing current pulses.8. Raising the pressure in the carotid sinus also depressed phrenic activity and evoked a hyperpolarization whilst the CPDP was suppressed.9. Inspiratory interneurones in the brain stem were suppressed by nerve stimulation and by a rise in carotid sinus pressure.10. Expiratory interneurones in the brain stem were both excited and suppressed by electrical stimuli and unaffected by a change in carotid sinus pressure.
Effects of intragastric hyperosmolal solutions on gastric functions
Authors: Harper A. A. , Reed J. D. , Smy J. R. 
Published: December 2014

1. The effects of intragastric hyperosmolal solutions on resting and secreting stomachs of anaesthetized cats have been studied.2. Hyperosmolal solutions reduced acid secretion in response to histamine and gastrin. There was a significant correlation between increase in osmolality and decrease in acid response to small doses of gastrin. A continuous acid secretion produced by large doses of gastrin was not significantly reduced.3. The loss of H+ from resting stomachs is related to the pH and osmolality of the instilled fluid. The loss was greatest at low pH and high osmolality, but was insufficient to account for the H+ loss from secreting stomachs at similar pH and osmolality.4. The Na+ output into resting stomachs was increased by hyperosmolal solutions, the increase being related only to the osmolality of the solutions. For the same degree of hyperosmolality there was no difference between the sodium output into resting and secreting stomachs.5. The H+ deficit associated with intragastric hyperosmolal conditions does not seem to depend upon a neural mechanism, a blood‐borne hormone, or a reduction in gastric blood flow. Evidence is presented that diffusion, exchange or neutralizing mechanisms are unlikely to be responsible for the H+ deficit. It is suggested that inhibition of oxyntic cell activity by release of a chemical agent from the surface cells of the mucosa is the most likely explanation of the results observed.6. The possible physiological significance of intragastric hyperosmolal inhibition of acid secretion is discussed.
Acetylcholine in adrenergic terminals of the cat iris
Authors: Ehinger B. , Falck B. , Persson H. , Rosengren A.-M. , Sporrong B. 
Published: December 2014

1. Acetylcholine was bio‐assayed in the normal cat iris, and also after selective sympathetic or parasympathetic denervation. Sympathetic denervation caused no significant change in the acetylcholine content of the cat iris, whereas selective parasympathetic denervation reduced the acetylcholine content below the level of detectability, which on the average was at about 5% of the acetylcholine content of the normal iris.2. It is concluded that if adrenergic terminals contain any acetylcholine, it is less than what is detectable with the methods available at present, and most certainly less than 6% of the acetylcholine content of cholinergic neurones.3. On the basis of these and other recently obtained observations, the hypothesis of Burn & Rand (1965) of a cholinergic link in the adrenergic transmission is discussed. It is proposed that it is more reasonable to suppose an interaction between peripheral adrenergic and cholinergic terminals than to presume a cholinergic mechanism within adrenergic nerve fibres.
The effect of procaine on neuromuscular transmission
Authors: Kordaš M. 
Published: December 2014

1. The mechanism of procaine action on post‐synaptic receptors for acetylcholine was studied by recording the end‐plate current at membrane potentials ranging from about +30 to about −140 mV.2. It has been found that at resting membrane potential of about −60 to −80 mV the end‐plate current has a fast initial and a slow late component. During hyperpolarization of the muscle fibre the amplitude of the slow component is depressed and its half‐time lengthened. When the membrane potential is inverted the difference in the time course of both components is much less pronounced or absent.3. It is suggested that procaine modifies the receptor response induced by acetylcholine, and that this modification is dependent on membrane potential.
The proprioceptive reflex control of the intercostal muscles during their voluntary activation
Authors: Davis J. Newsom , Sears T. A. 
Published: December 2014

1. A quantitative study has been made of the reflex effects of sudden changes in mechanical load on contracting human intercostal muscles during willed breathing movements involving the chest wall. Averaging techniques were applied to recordings of electromyogram (EMG) and lung volume, and to other parameters of breathing.2. Load changes were effected for brief periods (10–150 msec) at any predetermined lung volume by sudden connexion of the airway to a pressure source variable between ± 80 cm H2O so that respiratory movement could be either assisted or opposed. In some experiments airway resistance was suddenly reduced by porting from a high to a low resistance external airway.3. Contracting inspiratory and expiratory intercostal muscles showed a ‘silent period’ with unloading which is attributed to the sudden withdrawal from intercostal motoneurones of monosynaptic excitation of muscle spindle origin.4. For both inspiratory and expiratory intercostal muscles the typical immediate effect of an increase in load was an inhibitory response (IR) with a latency of about 22 msec followed by an excitatory response (ER) with a latency of 50–60 msec.5. It was established using brief duration stimuli (< 40 msec) that the IR depended on mechanical events associated with the onset of stimulation, whereas stimuli greater than 40 msec in duration were required to evoke the ER.6. For constant expiratory flow rate and a constant load, the ER of expiratory intercostal muscles increased as lung volume decreased within the limits set by maximal activation of the motoneurone pool as residual volume was approached.7. The ER to a constant load increased directly with the expiratory flow rate at which the load applied, also within limits set by maximal activation of the motoneurone pool.8. For a given load, the ER during phonation was greater than that occurring at a similar expiratory flow rate without phonation when the resistance of the phonating larynx was mimicked by an external airway resistance.9. It is argued that the IR is due to autogenetic inhibition arising from tendon organs and that the ER is due to autogenetic excitation arising from intercostal muscle spindles.10. The initial dominance of inhibition in this dual proprioceptive reflex control was not predicted by the servo theory. It is proposed that the reflex pathways subserving autogenetic inhibition are under a centrifugal control which determines in relation to previous experience (learning) the conditions under which autogenetic facilitation is allowed.
The relationship of blood flow to myoglobin, capillary density, and twitch characteristics in red and white skeletal muscle in cat
Authors: Reis Donald J. , Wooten G. Frederick 
Published: December 2014

1. The fractional distribution of blood flow was measured by the isotope dilution method and absolute blood flow estimated in twenty‐four muscles of chronically prepared, unanaesthetized cats.2. In the quiet, alert cat the estimated mean muscle blood flow ranged from 5·9 to 39·3 ml./min 100 g muscle. Flow was three times greater in grouped red than white limb muscles.3. The myoglobin concentration ranged from 0·88 to 3·91 mg/g muscle. The myoglobin concentration of grouped red exceeded that of white muscle and varied in each muscle directly and linearly with blood flow with a high correlation (P < 0·001).4. Capillary density was estimated by determination of alkaline phosphatase activity. Alkaline phosphatase activity was significantly greater in red than white muscles and varied directly with fractional blood flow in these same muscles with a high correlation (P < 0·001).5. Contraction time was generally two to three times longer in red than white muscle. There was a direct and highly correlated relationship (P < 0·001) between blood flow and contraction time.6. The direct linear relationship between muscle blood flow and myoglobin concentration, capillary density, and contraction time characteristic of quiet wakefulness was lost during rapid eye movement sleep or excitement produced by electrical stimulation of the hypothalamus as a consequence of selective changes in flow in red and white skeletal muscle.7. The type of metabolism of any skeletal muscle is adapted to its activity during quiet, alert behaviour, rather than during sleep or excitement.
Effect of neurohypophysial hormones on fluid movement across isolated bladder of Rana cancrivora, Rana temporaria and Bufo melanostictus
Authors: Dicker S. E. , Elliott Annie B. 
Published: December 2014

1. The rate of fluid movement across the wall of isolated amphibian urinary bladder was estimated using hemi‐bladders of the tropical euryhaline Rana cancrivora, the temperate R. temporaria and the tropical Bufo melanostictus.2. The rate of water outflow across the bladder walls was: Rana cancrivora, 4·8 μl./cm2.hr; R. temporaria, 7·2 μl./cm2.hr; Bufo melanostictus, 3·7 μl./cm2.hr.3. When neurohypophysial peptides were added to the serosal solution the rates of water outflow were increased; dose—response curves were prepared relating the augmented rate of fluid movement to the concentration in the bathing fluid of vasopressin, oxytocin or vasotocin.4. The potencies of the peptides in respect of bladders of each species were:Vasopressin, B. melanostictus:Rana temporaria:R. cancrivora, 500:20:1.Oxytocin, R. temporaria:B. melanostictus:Rana cancrivora, 100:5:1.5. The ratio of sensitivity of the bladder of each species to the presence of the different peptides was:R. cancrivora, vasotocin:oxytocin:vasopressin, 1000:5:1.R. temporaria, oxytocin:vasopressin, 15:1.Bufo melanostictus, oxytocin:vasopressin, 1:30.6. The effect of extract of the pituitary gland of Rana cancrivora was examined on R. cancrivora bladder. It had a dose—response curve similar to the dose—response curve of vasotocin.7. The vasotocin content of the pituitary gland of R. cancrivora was estimated(a) from the dose—response curves using R. cancrivora bladder,(b) by a three‐point assay using R. cancrivora bladder and(c) by its effect on water uptake across the skin of Bufo melanostictus. One pituitary gland of Rana cancrivora was found to contain about 0·1 μg vasotocin.8. The urinary bladder of R. cancrivora was less responsive to neurohypophysial peptides than the bladder of R. temporaria or Bufo melanostictus.9. The hormonal content of the pituitary gland of Rana cancrivora was smaller than that found in other amphibians.
Electrical activity in pancreatic islet cells: effect of ions
Authors: Dean P. M. , Matthews E. K. 
Published: December 2014

1. Intracellular micro‐electrode recording techniques have been used to study the effects of varying the external ion concentration on the membrane potential and glucose‐induced electrical activity in cells from mouse islets of Langerhans.2. Increasing [K]o to 47 m
M depolarized islet cells without inducing electrical activity. Normal action potentials were generated in response to glucose after removal of [K]o for 60 min.3. Reduction of [Cl]o to 12 m
M did not affect the membrane potential and glucose still induced electrical activity.4. Reduction of [Na]o to 26 m
M increased the amplitude of action potentials; subsequently the cells depolarized.5. Removal of [Ca]o caused cells, already firing action potentials intermittently in response to glucose, to change their pattern of discharge to one of continuous firing. The time constant of the action potentials was also increased. Depletion of calcium for 60 min before addition of glucose prevented the appearance of electrical activity.6. Increasing [Ca]o threefold to 7·7 m
M in the presence of glucose, 11·1 m
M, increased action potential amplitude to 12 mV, but a tenfold increase of [Ca]o to 25·6 m
M completely blocked action potential discharge.7. Exposure of islet cells simultaneously to reduced [Na]o (26 m
M) and increased [Ca]o (7·7 m
M) increased the amplitude of glucose‐induced action potentials to about 20 mV.8. Strontium, 2·56 m
M, was an effective substitute for [Ca]o, 2·56 m
M, and maintained a normal pattern of electrical activity in response to glucose.9. Increasing the magnesium concentration tenfold to 11·3 m
M did not block electrical activity whereas manganese, 2 m
M, blocked glucose‐induced action potentials and depolarized islet cells.10. It was concluded that the action potential induced by glucose in islet β‐cells is due predominantly to calcium entry and that sodium ions tend to repress this calcium influx.
Decamethonium in depolarized muscle and the effects of tubocurarine
Authors: Creese R. , England J. M. 
Published: December 2014

1. In rat diaphragms immersed in solution containing 5 m
M potassium the maximum uptake of labelled decamethonium was found at the end‐plate region. In muscles depolarized in solution containing potassium methyl sulphate the uptake was reduced but a peak concentration at the end‐plate region was still demonstrated.2. The uptake of labelled decamethonium increased steadily with time and was interpreted in terms of the entry of decamethonium into the fibres. The permeability at 10–100 μ
M was similar to that of sodium.3. The uptake of decamethonium at the end‐plate region was dependent on the concentration. At low values the uptake in depolarized muscle was uniform along the fibres. Increase in concentration produced a peak at the end‐plate region. This was interpreted as a change in permeability such that half the maximum effect was present at a concentration of approximately 5 μ
M.4. At high concentrations the influx showed saturation and carrier‐like kinetics with a half‐saturation concentration of 400 μ
M.5. Tubocurarine inhibited the peak uptake in depolarized diaphragm. The results were consistent with competitive inhibition with an inhibitory constant of 0·07 μ
M.6. Acetylcholine in high concentration also inhibited the uptake of decamethonium in the end‐plate region of depolarized muscle.
Entry of decamethonium in rat muscle studied by autoradiography
Authors: Creese R. , Maclagan Jennifer 
Published: December 2014

1. When a steady plasma level of decamethonium was maintained by infusion in rats, the labelled compound became concentrated in the region of the end‐plate of skeletal muscle, as shown by scintillation counting.2. The distribution of tritium‐labelled decamethonium in single muscle fibres was studied by autoradiography of frozen sections, with resolution less than 1 μ.3. After intravenous injection of a dose of decamethonium which produced partial paralysis it was shown that the labelled compound had entered muscle fibres in the region of the end‐plate, and for several hundred microns on either side of the end‐plate.4. Entry of decamethonium could be demonstrated as early as 30 sec after intra‐arterial injection. There was no evidence of any redistribution of labelled drug for a period of 2 hr after the initial entry.5. Previous administration of tubocurarine markedly reduced the entry of labelled decamethonium.
Observations on the mechanism of salicylate‐induced antipyresis
Authors: Cranston W. I. , Hellon R. F. , Luff R. H. , Rawlins M. D. , Rosendorff C. 
Published: December 2014

1. Fever has been produced in conscious rabbits, first, by injection of leucocyte pyrogen into the lateral cerebral ventricle and, second, by local cooling of the hypothalamus.2. Both intravenous and intraventricular salicylate produce antipyresis during an established fever due to intraventricular leucocyte pyrogen. This is incompatible with the hypothesis that salicylate acts by interfering with the passage of leucocyte pyrogen from the circulation into the hypothalamus.3. Intravenous sodium salicylate has no effect on the fever due to local cooling of the hypothalamus. This suggests that salicylates do not act on central or peripheral efferent pathways involved in thermoregulation.
The transparency of the mammalian cornea
Authors: Cox J. L. , Farrell R. A. , Hart R. W. , Langham M. E. 
Published: December 2014

1. A theoretical and experimental analysis of the relationship of the corneal stromal ultrastructure with light transmission has been made in an attempt to resolve recent contradictory explanations of corneal transparency.2. The spatial distribution of collagen fibrils in electronmicrographs of rabbit corneal stroma has been analysed in terms of a radial distribution function. The results indicate the presence of local order extending to at least 200 nm from individual fibrils.3. The observed spatial distribution of the collagen fibrils was used as a basis to compare the theoretically derived and the experimentally determined values of light transmission. It has been found that the transparency of the normal cornea may be explained by the quasi‐random structure revealed by the electronmicroscope.4. Histograms of the collagen fibril diameter in normal rabbit corneal stroma revealed the range to be 12·5–32·5 nm and the mean value to be approximately 20 ± 1·5 nm. Corneal swelling did not change the collagen fibril diameter significantly.5. It is concluded that the size and distribution of collagen fibrils revealed in electronmicrographs are consistent with the observed transparency of normal stromas.6. A marked heterogeneity in the spatial distribution of collagen fibrils was found in the swollen cornea. This is qualitatively consistent with the observed decrease in transparency.
Skeleto‐fusimotor fibres in the rabbit
Authors: Emonet‐Dénand Françoise , Jankowska Elżbieta , Laporte Y. 
Published: December 2014

1. In rabbits, repetitive stimulation of single motor axons to lumbrical muscles elicits both a contraction of extrafusal muscle fibres and an increase in the discharge frequency of spindle primary endings.2. This activation of the sensory endings can be attributed to the contraction of intrafusal muscle fibres because it persists after the contraction of extrafusal muscle fibres has been suppressed by selective curarization of their neuromuscular junctions.3. In non‐curarized preparations the frequency of most of the afferent discharges continues to increase when rates of stimulation of motor fibres exceed the tetanic fusion frequency of the extrafusal muscle fibres.4. The effect of repetitive stimulation of motor fibres that supply extrafusal and intrafusal muscle fibres was studied on the responses of primary endings to phasic stretch. Of twelve fibres, eight were found to exert a dynamic effect and four a static one.5. Selective curarization of the extrafusal neuromuscular junctions does not modify the nature of the static and dynamic effects.
Urinary excretion of adrenal steroids, catecholamines and electrolytes in man, before and after acclimatization to cold in Antarctica
Authors: Budd G. M. , Warhaft N. 
Published: December 2014

1. Urine samples were collected from four men before and during test cold exposures in Melbourne, Australia, and Mawson, Antarctica. Changes in the response of body temperature to the test exposures showed that the men had acclimatized to cold at Mawson.2. Excretion rates of 17‐hydroxycorticosteroids and 17‐ketosteroids were significantly greater at Mawson than in Melbourne, in both the pre‐exposure and exposure periods.3. Excretion rates of noradrenaline, adrenaline, sodium, potassium and creatinine did not differ significantly between Mawson and Melbourne, nor did urine flow rates.4. During the cold exposure significant increases occurred, to the same extent at Mawson as in Melbourne, in urine flow rate and in all measured urinary constituents except creatinine.
The kinetics of influx of calcium and strontium into rat intestine in vitro
Authors: Papworth D. G. , Patrick G. 
Published: December 2014

1. The role of uptake across the brush border in the intestinal absorption of calcium has been studied by examining the kinetics of influx into slices of rat intestine in vitro. Both mucosal and serosal surfaces were exposed to the medium.2. The rate of influx was accurately defined by a two‐component expression comprising a saturable (Michaelis—Menten) term and a second term linear with concentration. Influx across the mucosal surface of closed sacs was similar, and the saturable component for slice influx could be ascribed mainly to transport across the mucosal surface. The half‐saturation constant for Ca was near 1 m
M. This component was predominant at normal luminal concentrations of free Ca in the duodenum of young rats, but less so in jejunum and ileum and in older rats.3. The same kinetic expression applied to Sr influx, with a half‐saturation constant of 2‐3 m
M, and possibly also to Ba with an even higher value.4. The saturable component of Ca influx was greatly reduced by 2,4: dinitrophenol (DNP); influx was also inhibited by iodoacetate, cyanide and at 0° C. Inhibition commenced soon after exposure of the slices. A high concentration of DNP also caused an increase in the linear component of Ca influx.5. The kinetics of Ca influx across the mucosal surface agreed closely with the kinetics of steady‐state absorption of Ca either across the whole mucosal epithelium in vivo or across the entire intestinal wall in vitro. This agreement supports the hypothesis that Ca entry across the brush border is the rate‐limiting step in absorption; such a hypothesis would allow net Ca translocation while preserving a low intracellular concentration of ionic Ca in the mucosal epithelial cells.
Afferent vagal fibres with an expiratory discharge in the rabbit
Authors: Luck J. C. 
Published: December 2014

1. An investigation was undertaken in the spontaneously breathing, anaesthetized rabbit to observe the response of vagal sensory endings to inflation and deflation stimuli which were sufficient to produce Hering—Breuer reflexes.2. When artificial changes in lung volume were produced by applying step changes in intratracheal pressure, activity in pulmonary stretch receptors increased with inflation and decreased with deflation.3. A small number of vagal afferent fibres were encountered which exhibited a discharge with a respiratory modulation consisting of an increase in activity during the phase of expiration. This pattern of discharge was accentuated when the animal was artificially ventilated with the chest either open or closed.4. These expiratory receptors were stimulated by step changes in intratracheal pressure of −5 and +15 mm Hg to produce a high frequency, slowly adapting discharge which persisted for the 10 sec period of the pressure application. The endings were localized in the extrapulmonary bronchi and lung parenchyma and the afferent fibres were myelinated with conduction velocities of 10·6–29·5 m/sec.5. The pronounced effect of deflation stimuli on the endings indicates that they probably act as one of the afferent mechanisms in the Hering—Breuer deflation reflex.