bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gastric secretion and its facilitation as related to gastric mucosal histamine
Authors: Johansson Irene , Lundell L. , Rosengren Elsa , Svensson S. E. 
Published: December 2014

1. In conscious rats provided with Pavlov or Heidenhain pouches the acid and pepsin responses to vagal stimulation, or infusions of gastrin, histamine, methacholine, and to various combinations of these stimulants have been established. The concomitant mobilization and increased formation of gastric mucosal histamine have also been examined.2. Histamine evoked graded acid responses in the Pavlov and Heidenhain pouches. The innervated pouch was more sensitive to histamine than the denervated. Stimulation of pepsin secretion was apparent only in the Heidenhain pouch.3. The acid response to vagal stimulation evoked by 2‐deoxy‐
D‐glucose was facilitated by infusion of histamine, but not that of pepsin, the secretion of which was depressed.4. Acid secretion in response to graded infusion of methacholine was enhanced by background infusions of histamine in subthreshold, sub‐maximal and maximal dosages.5. The acid response to vagal stimulation was enhanced by a background infusion of gastrin, but not that of pepsin, the secretion of which was depressed.6. A background infusion of a large dose of histamine depressed the maximal acid response to gastrin in both types of pouches.7. Administration of histamine restrained the accelerating effect of gastrin on histidine decarboxylase activity, probably by a feed‐back coupling.8. The increase in gastric mucosal histamine, as reflected in its urinary excretion, in response to gastrin infusion was enhanced by vagal stimulation.9. The amounts of histamine that can be mobilized and newly formed in the gastric mucosa have been evaluated and found to be fully adequate for efficient stimulation of the parietal cell.
An experimental analysis of the tachycardia that follows vagal stimulation
Authors: Burke G. H. , Calaresu F. R. 
Published: December 2014

1. Postvagal tachycardia, the transient increase in heart rate that follows the sinus bradycardia elicited by vagal stimulation, was investigated in thirty chloralosed cats. Maximum postvagal tachycardia was elicited by stimulation at frequencies of 20–60 Hz with train durations of 30–90 sec. A positive correlation was demonstrated between the magnitudes of postvagal tachycardia and of the preceding sinus bradycardia.2. Postvagal tachycardia was not affected by either spinal transection at C7 or by administration of propranolol (1·5 mg/kg
I.V.), but was abolished by the administration of atropine (2·0 mg/kg
I.V.).3. Postvagal tachycardia was observed to follow the vagal bradycardia induced reflexly either by administration of phenyldiguanide (100–300 μg
I.V.) or by stimulation of the aortic depressor nerve.4. In the isolated atria‐vagus preparations from six rabbits a positive correlation was demonstrated between the magnitude of postvagal tachycardia and of the preceding bradycardia elicited by vagal stimulation.5. Continuous intracellular recordings were obtained from four sinuatrial node pace‐maker cells in the isolated atria‐vagus preparation of the rabbit before, during and after vagal stimulation. During postvagal tachycardia the slope of the diastolic prepotential, the maximum diastolic potential, threshold potential and the overshoot were found to be increased; these changes are different from those found in pace‐maker cells during adrenergic activation.6. These findings demonstrate that postvagal tachycardia is not mediated by sympathetic adrenergic mechanisms, but suggest that it is dependent upon the preceding vagal bradycardia and may be related to an increase in net sodium influx into pace‐maker cells initiated by the hyperpolarization of the pace‐maker cell membrane during and immediately after vagal stimulation.
Inhibition of post‐ganglionic motor transmission in vas deferens by indirectly acting sympathomimetic drugs
Authors: Ambache N. , Dunk Linda P. , Verney J. , Zar M. Aboo 
Published: December 2014

1. Using field stimulation with short trains of pulses (< 10 per train), the post‐ganglionic motor transmission in the mammalian vas deferens has been further analysed pharmacologically.2. In preparations taken from guinea‐pigs, rats and rabbits the effects of the indirectly sympathomimetic drugs, tyramine and cocaine, could be explained entirely on the basis of the actions of released, endogenous noradrenaline.3. Tyramine produced a contraction in vasa taken from normal rats but not from normal guinea‐pigs. The tyramine contraction was due to release of endogenous noradrenaline because it was not seen in preparations taken from reserpinized rats and because it was abolished in normal vasa by phenoxybenzamine or phentolamine, thus denying the supposed inaccessibility, to α‐blockers, of the motor α‐adrenoceptors activated by endogenous noradrenaline.4. Phenoxybenzamine or phentolamine failed to block post‐ganglionic motor transmission in rat and in guinea‐pig vasa.5. Tyramine strongly inhibited motor transmission in vasa taken from normal but not from reserpinized guinea‐pigs.6. Tyramine produced inhibition of motor transmission in phenoxybenzamine‐treated preparations taken from normal but not from reserpinized rats.7. Cocaine inhibited motor transmission in guinea‐pig and in rat vasa. This effect was not due to a local anaesthetic or to a smooth‐muscle depressant action because it did not occur in preparations taken from reserpinized animals.8. The inhibitory effect of tyramine or cocaine was not abolished by β‐adrenoceptor blockade with propranolol.9. Whereas reserpinization abolished the tyramine‐ and cocaine‐inhibitions, it did not affect the inhibitory actions of noradrenaline or of PGE2.10. Indomethacin and sodium meclofenamate, which suppress prostaglandin synthesis, did not affect the twitch‐inhibiting actions of noradrenaline, tyramine or cocaine.11. These results provide further support for the conclusion that post‐ganglionic motor transmission to the vas deferens is non‐adrenergic in these species and assign to endogenously released noradrenaline an inhibitory role upon motor transmission.
The propagation of segmental contractions along the small intestine*
Authors: Grivel M‐L. , Ruckebusch Y. 
Published: December 2014

1. The electrical activity of the small intestine of conscious dogs, rabbits and sheep was recorded by means of chronically implanted electrodes and was related to mechanical changes in the bowel.2. A pattern of activity characteristic of segmental contractions (a prolonged series of bursts of spike activity superimposed on the basic electrical rhythm) was recorded successively at consecutive sites along the small intestine. This activity was as pronounced in the rabbits and sheep which were fed ad lib. as in the dogs which were fasted for 12 hr.3. The segmental contractions began in the duodenum and had a frequency of 15–20/24 hr. As they passed along the intestine, their velocity diminished and in the rabbits and sheep this was associated with an increased duration of activity. Most of the contractions reached the terminal ileum taking 1·5‐2 hr in each of the species despite the differences in the length of the small intestine.4. The propagation of segmental contractions appears to be a normal and common activity of the intact bowel and it may have a propulsive as well as a mixing function.
The role of circulating catecholamines in sweat production in man
Authors: Allen Judith A. , Roddie I. C. 
Published: December 2014

1. The effects of intravenous infusions of adrenaline, isoprenaline and noradrenaline on human sweating were assessed by continuous measurement of total body weight loss in normal subjects.2. All three catecholamines increased the rate of weight loss but isoprenaline was effective in a much smaller dosage than either adrenaline or noradrenaline.3. β‐adrenoceptor blockade with propranolol reduced the response.4. The response was not abolished by collecting expired air in a Douglas bag suggesting that it was not due to an increase in respiratory water loss.5. The response was not abolished by atropine infusions suggesting that it was not mediated through cholinergic sudomotor nerves.6. It is concluded that intravenous infusions of catecholamines may elicit a small, non‐cholinergically mediated sweat response in man.
The effects of tetanus toxin on neuromuscular transmission and on the morphology of motor end‐plates in slow and fast skeletal muscle of the mouse
Authors: Duchen L. W. , Tonge D. A. 
Published: December 2014

1. A sublethal dose of tetanus toxin was injected into the muscles of one hind leg of the mouse and caused local tetanus which persisted for 4 weeks.2. Neuromuscular transmission was studied in vitro in nerve—muscle preparations of soleus, a slow muscle, and extensor digitorum longus (EDL), a fast muscle, from 1 day to 6 months after the injection of toxin.3. Soleus failed to respond to nerve stimulation, became supersensitive to acetylcholine and showed spontaneous fibrillations for several weeks before returning to normal. EDL did not show these changes. A higher dose of tetanus toxin, lethal within 24 hr, caused paralysis of EDL as well as soleus.4. In muscle fibres in which neuromuscular transmission was blocked spontaneous miniature end‐plate potentials (m.e.p.p.s) were recorded. The frequency of m.e.p.p.s was increased by repetitive nerve stimulation but not by raising the external potassium concentration.5. The amplitude of spontaneous m.e.p.p.s showed a skew distribution because of a disproportionate number of potentials of less than 0·2 mV.6. Raising the external calcium concentration did not restore neuromuscular transmission.7. Histological examination of soleus showed atrophy of muscle fibres with normal preterminal axons. There was sprouting from motor nerve terminals and subsequently new motor end‐plates were formed. These changes were not found in EDL.8. The results indicate that, in the mouse, tetanus toxin causes a presynaptic block of neuromuscular transmission and ‘functional denervation’ of muscle. Slow muscle is more sensitive to the effects of the toxin than fast.
Input from muscle and cutaneous nerves of the hand and forearm to neurones of the precentral gyrus of baboons and monkeys
Authors: Wiesendanger M. 
Published: December 2014

1. The precentral bank of the Rolandic fissure of the cortical arm area has been explored with extracellular micro‐electrodes in primates (baboons and monkeys) under nitrous oxide and oxygen anaesthesia, supplemented by small doses of Parkesernyl® and chloralose. The results in baboons and monkeys were the same.2. Single units were classified as pyramidal tract neurones or non‐pyramidal tract neurones according to their antidromic responsiveness to stimuli applied in the dorsolateral funiculus at C1–2.3. Responses to electrical stimulation of the deep (motor) radial nerve, the deep palmar (motor) branch of the ulnar nerve, and the superficial (cutaneous) radial nerve could be recorded in the majority of neurones of the motor cortex provided that short trains of strong stimuli were used. Minimal responses to muscle nerve stimulation were observed in a few neurones at 1·4 × group I threshold, but most units reacted only with higher stimulus intensities (2–3 × group I threshold).4. The latencies to peripheral nerve stimulation were measured from the first peak of the incoming volley recorded at the root entry zone. The mean response latencies of pyramidal tract cells were between 20 and 25 msec; non‐pyramidal tract cells were activated at slightly shorter mean latencies, the difference being significant for superficial radial nerve stimulation only (4 msec). These latencies are more than twice as long as those recorded in the postcentral gyrus, and the probability of discharge is lower than for postcentral neurones.5. A further difference between neurones of the postcentral and precentral gyrus is the pronounced convergence from different nerves and also from different modalities (cutaneous and muscle afferents) in units of the precentral cortex in contrast to units of the postcentral cortex.6. The high thresholds, necessary to activate precentral neurones by muscle nerve stimulation, make it unlikely that group I muscle afferents are involved. This is, furthermore, indicated by the lack of responsiveness to intravenous injection of succinylcholine which was, however, effective for driving neurones of the specific projection area for group I afferents, area 3a. The present experiments are consistent with the view that sensitivity of precentral neurones to muscle stretch (described in previous studies) is due to activation of secondary muscle spindle endings and their ascending pathways.7. The original hypothesis of a load compensating ‘pyramidal reflex’ with an oligosynaptic afferent contribution from the spindle primaries can be discarded. The present findings indicate that there is a feed‐back from secondary muscle spindle afferents which, by way of a more complex pathway, can modulate the firing frequency of neurones in the motor cortex.
Somatotopic organization of vibrissal responses in the ventro‐basal complex of the rat thalamus
Authors: Waite Phil M. E. 
Published: December 2014

1. The region of the ventro‐basal complex (VB) of the thalamus responding to movements of the whiskers has been mapped electrophysiologically in rats under either urethane or barbiturate anaesthesia.2. Whisker responses were found in the dorso‐medial part of VB throughout its rostro‐caudal extent; they occupied one third to one half of the total VB region.3. Most cells responded to movements of only one whisker and the responses were somatotopically organized. The different horizontal lines of whiskers were represented at different rostro‐caudal levels within the nucleus, the most dorsal line being represented most caudally. At each level the larger, more caudal whiskers were represented more dorsally and laterally than the smaller, more rostral whiskers.
Salt adaptation in Bufo bufo
Authors: Ferreira H. G. , Jesus C. H. 
Published: December 2014

1. The capacity of adaptation of toads (Bufo bufo) to environments of high salinity was studied and the relative importance of skin, kidney and urinary bladder in controlling the balance of water and salt was assessed.2. Toads were kept in NaCl solutions of 20, 50, 110, 150 and 220 m
M and studied in their fourth week of adaptation. A group of animals considered as ‘control’ was kept in wet soil with free access to water. Plasma, ureter urine, and bladder and colon contents were analysed for sodium, potassium, chloride and osmolality, and total body sodium and water were determined. Absorption of water and 22Na through the skin, and water flow and sodium excretion through the ureter, of intact animals was studied. Hydrosmotic water transport through the isolated urinary bladder of ‘control’ and adapted animals was determined. The effects of pitressin and aldosterone on the water and sodium balance are described.3. The survival rates of toads kept in saline concentrations up to 150 m
M were identical to that of ‘control’ animals, but half of the animals kept in 220 m
M died within 4 weeks.4. There is a linear correlation between the sodium concentrations and osmolality of plasma and of the external media.5. The sodium concentration in colon contents rose with rising external concentrations, up to values higher than the values in plasma.6. Sodium concentrations and osmolalities of ureter and bladder urine increased in adapted animals, the values for bladder urine becoming much higher than those for ureter urine in animals adapted to 110, 150 and 220 m
M.7. Total body water, as a percentage of total weight was kept within very narrow limits, although the total body sodium increased with adaptation.8. Absorption of water through the skin for the same osmotic gradients was smaller in adapted than in ‘control’ animals.9. The ureteral output of water of toads adapted to 110 and 150 m
M‐NaCl was larger than the water absorption through the skin.10. Skin absorption of sodium was lower in animals adapted to concentrated saline solutions than in ‘control’ animals.11. Sodium output by the ureter was identical to skin absorption in ‘control’ animals adapted to 20, 50 and 110 m
M‐NaCl but was higher in animals adapted to 150 m
M‐NaCl.12. Aldosterone increased the absorption of sodium in ‘control’ and adapted toads, but at all dose levels absorption by control was greater than by adapted animals.13. The stimulation of water absorption by vasopressin in vivo or in isolated bladders was not modified in animals adapted to high salinities.
Presbyopia and the changes with age in the human crystalline lens
Authors: Fisher R. F. 
Published: December 2014

1. A method of determining the distribution of capsular moulding pressure is described. This includes:(a) measuring the decrease in polar depth of the lens from photographed lens profiles before and after the capsule has been cut around the entire equator of the lens,(b) measuring the elastic properties of the lens substance by subjecting the lens to known centrifugal forces and photographing the polar strain so produced.2. A method of determining the relationship between capsular and lenticular strain is described. This includes (a) measuring the elastic properties of the capsule (b) measuring the elastic properties of the lens substance and (c) measuring the profiles of the photographed lens.The ratio of the strain of lens substance to capsule is expressed as a dimensionless parameter, the lens number.3. The decrease in the amplitude of accommodation with increasing age is proportional to the lens number divided by the square of the radius of the accommodated lens, assuming that the movement of the capsulozonular attachments of the lens remains unimpaired in the ageing eye.4. Ageing changes in the human crystalline lens are sufficient to account for a total loss of accommodation by the age of 61 years.
Left ventricular contractility and developed tension in the intact dog submitted to an intracoronary infusion of adenosine
Authors: Lammerant J. , Becsei I. 
Published: December 2014

1. The effect of adenosine on left ventricular contractility and developed tension was studied in the anaesthetized intact dog. Normal and propranolol‐treated animals were used. Adenosine was infused through a catheter into one of the two main branches of the left coronary artery, usually the circumflex branch. The rate of infusion was 150 × 10−9
M/min. The infusion was maintained during 50 min.2. In both series of animals, no change was observed in the heart rate, aortic pressure, left ventricular end‐diastolic pressure, time from onset of left ventricular contraction to peak dP/dt, peak dP/dt and left ventricular tension—time index. It is concluded that a regional increase in adenosine concentration in the left ventricular wall has no inotropic effect when the adrenergic mechanisms are normal or depressed.3. The myocardial blood flow response to adenosine was determined at the 10th, 30th and 50th min of the infusion by the radioactive inert gas method. At the 10th min of the infusion, the myocardial blood flow averaged three times the control value in both series of dogs. Thereafter, the flow response remained stable in the normal dogs but declined at the 50th min of the infusion in the propranolol‐treated animals. It is suggested that autoregulation of the coronary circulation in response to overperfusion of the myocardium at constant cardiac work may be enhanced at the lower myocardial oxygen requirements of the propranolol‐treated dogs while, in the normal animals, it was insufficient to overcome the potent coronary dilator action of adenosine.
The pontomedullary area integrating the defence reaction in the cat and its influence on muscle blood flow
Authors: Coote J. H. , Hilton S. M. , Zbrożyna A. W. 
Published: December 2014

1. In anaesthetized cats the effects were investigated of electrical stimulation of regions in the caudal mesencephalon, pons and medulla on muscle blood flow, skin blood flow and arterial blood pressure.2. It was found that within the dorsal part of the well known pressor area there is a narrow strip, 2·5 mm lateral from the mid line, starting ventral to the inferior colliculus and ending in the medulla close to the floor of the IV ventricle, from which vasodilatation in skeletal muscles is selectively obtained. This strip is quite separate from the more ventral, efferent pathway for active vasodilatation running from the hypothalamic and rostral mesencephalic ‘defence centre’.3. As in the case of the hypothalamic and rostral mesencephalic ‘defence centre’, the muscle vasodilatation obtained from the caudal strip is accompanied not only by a rise of arterial blood pressure, but also by tachycardia, vasoconstriction in the skin, pupillary dilatation and piloerection.4. Stimulation, restricted to the caudal strip, via implanted electrodes in unanaesthetized animals, produced a behavioural response resembling the defence reaction. The strip, therefore, is probably a caudal extension of the ‘defence centre’.5. Unlike the vasodilatation elicited from the more rostral part of the ‘defence centre’ in the hypothalamus and mesencephalon, the muscle vasodilatation obtained on stimulation of the caudal strip was resistant to atropine, but was blocked by guanethidine.6. It is suggested that during naturally occurring defence reactions in the normal animal the ponto‐medullary area is activated together with the hypothalamo‐mesencephalic area, inhibition of vasoconstrictor tone then accompanying activation of the vasodilator nerve fibres in skeletal muscle.
The maintenance of arterial constriction at different transmural pressures
Authors: Speden R. N. 
Published: December 2014

1. Distensibility characteristics of the isolated, perfused rabbit ear artery were measured in the presence and absence of different concentrations of adrenaline.2. The major effect of varying the adrenaline concentration was to vary the radius at which active tension first developed. This radius was inversely related to the adrenaline concentration.3. Increases in radius of the constricted artery produced by pressures rising from 40 to 150 mm Hg were small relative to the increase in wall stress. Distension was opposed largely by increases in active tension. With some arteries (60%) an increase in pressure between 30 and 80 mm Hg was associated with a decrease in radius when low concentrations of adrenaline were present.4. The ability of the constricted ear artery to resist distension at transmural pressures of 100 mm Hg was uninfluenced by the adrenaline concentration provided constriction exceeded 28% of maximal. The static, incremental, circumferential modulus of the artery wall varied little from a value of 6·5 × 106 dyn/cm2.5. The maximum active tension required to maintain constriction was inversely related to the degree of constriction and hence to the adrenaline concentration. The modulus for fully or near‐fully activated muscle was 18·5 × 106 dyn/cm2 of media.6. Muscle function deteriorated following exposure of constricted arteries to pressures sufficient to overwhelm the constriction.7. These observations may be explained by a negative feedback system where the contractile elements are arranged in parallel with a length sensor element whose setting is determined by the concentration of adrenaline. The length sensor may be the cell membrane. It is concluded that a radius increase may be a primary stimulus for blood flow auto‐regulation.