Showing papers on "Autonomic nervous system published in 1973"

Physical training, bradycardia, and autonomic nervous system.

Abstract: In order to study the bradycardia evoked by physical training 14 subjects were given atropine, propranolol, or both drugs simultaneously before and after a 5 weeks' physical training period. For a given ‘relative’ (per cent of maximum) submaximal oxygen uptake the activity of the autonomic nervous system was similar before and after the training. It is suggested that the training bradycardia in previously sedentary individuals after a short-term physical training period is due both to a reduced beta-adrenergic receptor activity and to an increased para-sympathetic activity.

Development of cardiovascular responses to autonomic blockade in intact fetal and neonatal lambs.

Abstract: Blood pressure and heart rate response to pharmacologic autonomic blockade were studied in the 31 fetuses of 27 time-dated pregnant sheep from 85 to 150 days of gestation and in 5 neonatal lambs. A fe

Autonomic Nervous System and Diabetes: Histological and Histochemical Study of the Autonomic Nerve Fibers of the Urinary Bladder in Diabetic Patients

Abstract: Reports on the histologic aspects of the autonomic nerves in diabetics are infrequent. This investigation was carried out to study histologically and histochemically the autonomic nerve fibers of the urinary bladder wall in ten diabetic patients. Of the five subjects examined by biopsy, four showed damage of nerve fibers; absence of cholinesterase activity was the only finding in the fifth patient who had chemical diabetes. In four autopsies we found alterations in all the cases. The lesions appeared as beaded or spindle-shaped fibers or small vacuolated or uniformly thickened fibers. The most severe cases exhibited fragmentation of the fibers. Histochemical analysis demonstrated absence of cholinesterase activity in the muscle, in all cases, and absence or decrease of such activity in the nerves in all but one case. Similar studies performed on eight nondiabetic subjects revealed no anatomic or histochemical lesions. The findings lead to the hypothesis that diabetic neuropathy injures the biochemical phase ofthe myelin sheath in the first stage and the nerve fibers later. No previous reports on the subject here studied could be found in the literature.

Role of central blood volume in hyperkinetic borderline hypertension.

Abstract: Forty-nine patients with hyperkinetic borderline hypertension were compared to 64 healthy volunteers. Central bloodvolume in thepatients was slightly raised. However, a detailed analysis of the results indicates that redistribution of the bloodfrom the peripheral to central veins is not responsiblefor the rise in cardiac output and stroke volume in hyperkinetic patients. The results in a subgroup of patients who received an autonomic blockade with atropine and propranolol support the concept that the autonomic nervous system is responsible for the rise in cardiac output, heart rate, and stroke volume in these patients.

Effects of narcotic analgesics and their antagonists on the rabbit isolated heart and its adrenergic nerves.

Abstract: 1. In isolated perfused hearts of rabbits, the effects of morphine, methadone, pethidine, fentanyl, levallorphan and naloxone on heart rate, the spontaneous outflow of noradrenaline, the uptake of infused noradrenaline and the overflow of noradrenaline in response to stimulation of the accelerans nerves were investigated.2. At concentrations of 10-100 muM, methadone, fentanyl, levallorphan and naloxone, but not morphine and pethidine, decreased the heart rate. Only pethidine and levallorphan (100 muM) augmented the spontaneous outflow of noradrenaline.3. With the exception of naloxone, all drugs diminished the neuronal uptake of noradrenaline from the perfusion fluid. Methadone and pethidine (1 muM) were the most effective inhibitors. The inhibitory effect of morphine was not antagonized by naloxone.4. All drugs increased the overflow of noradrenaline evoked by stimulation of the accelerans nerves at 5 Hz. Simultaneously, the positive chronotropic effect of stimulation was usually enhanced. Morphine also augmented the response to stimulation at 2.5 and 10 Hz. The effect of morphine was prevented by pre-infusion of cocaine. The response to stimulation was never depressed.5. It is concluded that the adrenergic nerves of the rabbit heart lack specific morphine receptors which in some other sympathetic nerves mediate an inhibition of the stimulation-induced secretion of noradrenaline. The mechanism of the enhancement of adrenergic neurotransmission by relatively high concentrations of the drugs is discussed.

Aging and the extrapyramidal system.

Abstract: : The role of the extrapyramidal system in the pathophysiology of aging is reviewed. The clinical, pathological and biochemical evidence points to the involvement of the basal ganglia in the development of senescence; also, the hypothalamus does not respond normally. Many endocrine functions decrease with advancing age, but senescence of the central nervous system precedes that of the endocrine organs. Aging can be considered as a failure in the homeostatic mechanism of the organism. This involves the autonomic nervous system and the neuroendocrine mechanisms in the hypothalamus. Aging of the diencephalon influences the aging process of the whole organism, and is manifested by slowness of movements, defects in speech, thinking and alertness, decreased sexual activity, and changes in the waking/sleep pattern.

The spinal origin of the motor and inhibitory innervation of the rat anococcygeus muscles

Abstract: 1. A preparation is described whereby the responses of the two anococcygeus muscles can be recorded in vivo in the pithed rat and the autonomic outflows to the muscle selectively stimulated in the spinal canal.2. Motor responses are obtained from stimulation at two levels; an upper extending from T 11 to L 3 and a lower from L 6 to S 2. Stimulation between these levels, i.e. between L 3 and L 6, produces no response. The response to stimulation at both upper and lower levels is abolished by phentolamine. The response to stimulation in the upper region is abolished by hexamethonium and is, therefore, presumably preganglionic; the response to stimulation at the lower level is resistant to hexamethonium and presumably post-ganglionic. Stimulation at levels above T 11 causes contraction after a delay, by liberating catecholamines from the adrenal medulla. This effect is blocked by both phentolamine and hexamethonium.3. If the adrenergic motor nerves are blocked and the muscle tone raised by a combination of guanethidine and tyramine, stimulation between L 5 and S 2 produces inhibition. The inhibitory outflow, therefore, overlaps the motor outflow but extends one segment more rostral (L 5). Stimulation restricted to this L 5 segment even in the presence of a normal unblocked motor innervation causes inhibition. The inhibitory response is blocked by hexamethonium or mecamylamine but desensitization and ;escape' occurs. This desensitization is less than that observed in the vas deferens when its motor nerves are similarly stimulated in the spinal cord.4. It is concluded that inhibitory fibres to the anococcygeus arise in the spinal cord and are organized in the pattern of the autonomic nervous system with a peripheral synapse. The site of origin of these inhibitory fibres is different from the motor adrenergic fibres to the muscle.

Autonomic nervous system and oviduct function in the rabbit

Abstract: Resistance to perfusion of the oviducal isthmus in anaesthetized rabbits was enhanced by adrenaline and depressed by isoprenaline. Ovariectomy significantly decreased the response of the oviducal musculature to both autonomic drugs. The degree of response of adrenergic alpha and beta receptors was primarily dependent upon oestrogen and progesterone, respectively. Increased spontaneous activity of the tubal musculature following ovariectomy appeared to be related to oestrogen withdrawal.

Effect of Change of Posture on Blood Pressure and Plasma Renin Concentration in Men with Spinal Transections

Abstract: 1. Blood pressure, heart rate and changes of plasma renin concentration (PRC) have been studied in nineteen patients with traumatic transection of the spinal cord, in relation to change of posture from supine to upright. 2. When supine, subjects with cervical-cord transection had a normal blood pressure, a low heart rate and a high plasma renin concentration. On change of posture to the vertical, orthostatic hypotension developed, heart rate rose and PRC increased. Orthostatic hypotension was not a feature with change of posture in patients with transection of the thoracic spinal cord and PRC rose to a much smaller extent. 3. It is concluded that release of renin on change of posture can occur in patients with spinal-cord transection. Release of renin in man does not depend therefore upon an intact autonomic nervous system, though it is possible that reflex sympathetic pathways in the isolated spinal cord may be involved.

Mechanisms Regulating the Cardiac Output Response to Cyanide Infusion, a Model of Hypoxia

Abstract: When tissue metabolic changes like those of hypoxia were induced by intra-aortic infusion of cyanide in dogs, cardiac output began to increase after 3 to 5 min, reached a peak (220% of the control value) at 15 min, and returned to control in 40 min. This pattern of cardiac output rise was not altered by vagotomy with or without atropine pretreatment. However, this cardiac output response could be differentiated into three phases by pretreating the animals with agents that block specific activities of the sympatho-adrenal system. First, ganglionic blockade produced by mecamylamine or sympathetic nerve blockade by bretylium abolished the middle phase of the cardiac output seen in the untreated animal, but early and late phases still could be discerned. Second, beta-adrenergic receptor blockade produced by propranolol shortened the total duration of the cardiac output rise by abolishing the late phase. Third, when given together, propranolol and mecamylamine (or bretylium) prevented most of the cardiac output rise that follows the early phase. When cyanide was given to splenectomized dogs, the duration of the cardiac output response was not shortened, but the response became biphasic, resembling that seen after chemical sympathectomy. A similar biphasic response of the cardiac output also resulted from splenic denervation; sham operation or nephrectomy had no effect on the monophasic pattern of the normal response. Splenic venous blood obtained from cyanide-treated dogs, when infused intraportally, caused an increase in cardiac output in recipient dogs; similar infusion of arterial blood had no effects. These results suggest that the cardiac output response to cyanide infusion consists of three components: an early phase, related neither to the autonomic nervous system nor to circulating catecholamines; a middle phase, caused by a nonadrenergic humoral substance released from the spleen by sympathetic stimulation; and a late phase, dependent upon adrenergic receptors but not upon sympathetic transmission.

A model of the human circulation. Regulation by autonomic nervous system and renin-angiotensin system, and influence of blood volume on cardiac output and blood pressure.

Abstract: In our model of the human circulation, the normal distribution and flow of blood to the systemic compartments and the central blood volume are regulated by the autonomic nervous system. Central blood volume (CBV), cardiac output (CO), and arterial pressure (AP) are stabilized during postural change and after loss or transfusion of blood, so long as autonomic control is normal; but autonomic blockade results in increased sensitivity of CBV, CO, and AP to changes in total blood volume. The autoregulated renal circulation, the release of renin, and the generation of angiotensin are simulated by the model under physiological conditions. The vasoconstrictor effects of angiotensin II are dependent on sodium balance and other factors affecting the concentration of circulating angiotensin and its interaction with receptors in arterioles. Wide variations in plasma renin activity (PRA), autonomic responses, plasma volume, peripheral resistance, and cardiac output have been found in different groups of hypertensive patients. The different constellations of pathological physiological data suggest at least two general classes of hypertension: one group associated with increased autonomic activity or circulating catecholamines, high PRA, low to normal plasma volume, and high to normal cardiac output; and a second group having increased exchangeable sodium, high-normal plasma volume, subnormal PRA, and often evidences of impaired autonomic function. Possible models of each type are proposed, relating the differences in pathogenesis and pathophysiology.

Effect of 9 - and 8 -tetrahydrocannabinol on the peripheral autonomic nervous system in vitro.

Abstract: The purpose of this study was to evaluate the effect of Δ9- and Δ8tetrahydrocannabinol (THC) on some isolated muscles. The results observed show that Δ9- and Δ8THC do not have agonistic activity on the vas deferens, the phrenic nerve – diaphragm, and the ileum preparations. On the other hand, both compounds produce a transient potentiation followed by the inhibition of the acetylcholine-induced contraction as well as a potentiation of the musculotropic activity of noradrenaline on the isolated vas deferens. Furthermore, we have observed that Δ8THC reverses the anti-cholinergic action of atropine, conteracts the anti-angiotensin activity of morphine, and finally, abolishes the potentiation of noradrenaline produced by cocaine. On the phrenic nerve – diaphragm preparation Δ9THC does not modify the contraction produced by nerve stimulation but alters the effect of physostigmine, an anti-cholinesterase inhibitor.

The inhibitory and motor innervation of the anococcygeus muscle

Abstract: (1) The subject of this thesis was the investigation of the dual innervation of the anococcygeus muscle. The rat anococcygeus had previously been shown in vitro to have a motor adrenergic innervation and also an inhibitory nerve response whose transmitter was unknown. (2) The object of the present study was threefold - (a) To determine whether this inhibitory response was due to a nerve pathway distinct from the motor innervation and with a separate spinal origin and if so whether this pathway had a ganglion synapse and so could be considered as part of the autonomic nervous system. (b) To compare the pharmacological properties of the anococcygeus muscle and vas deferens and to determine whether the rate of depletion of noradrenaline by reserpine in these two tissues was affected by nerve stimulation. (c) To compare the properties of the anococcygeus muscles from the cat and the rat in order to find whether the dual innervation found in the rat was represented in this further species and if so whether this comparison would throw any more light on the nature of the inhibitory response. (3) Using a pithed rat preparation permitting selective stimulation of the autonomic spinal outflows, it was shown that the inhibitory pathway to the anococcygeus muscles arose from the spinal canal, that it was interrupted by a ganglion synapse and that the spinal origin of its preganglionic nerves was L5 - S2 as opposed to T10 - L3 for the preganglionic nerves in the motor pathway. (4) Using this same preparation, the pharmacological properties of the motor nerves to the anococcygeus were examined in situ and compared with those of the vas deferens. This comparison demonstrated that the pharmacological properties of the anococcygeus motor innervation were those of a classical adrenergic innervation whereas the vas deferens showed responses which were in themselves complex and showed unconventional responses to drugs. A hypothesis is suggested to explain this unconventional nature of the vas deferens response. (5) An analysis of the dose dependence and time course of the depletion of tissue noradrenaline by reserpine showed that the rat anococcygeus and vas deferens were depleted to a similar extent and at a similar rate and that this was slower than that found in the heart. Increase in sympathetic nerve activity by spinal stimulation in pithed rats significantly increased the noradrenaline depletion in both anococcygeus and vas deferens. From this it is suggested that nerve impulse traffic may be an important factor in determining the rate of depletion of noradrenaline by reserpine and in the vas deferens may explain the apparent resistance to depletion. (6) The cat anococcygeus muscle was investigated in vitro and shown to possess a dual innervation similar to that in the rat. Due to the presence of intrinsic tone, both motor and inhibitory nerve responses could be demonstrated in the absence of blocking drugs and their interaction studied. The pharmacological properties of the cat anococcygeus were similar to those of the rat except that several substances relaxed the cat muscle which contracted the rat including acetylcholine, isoprenaline, prostaglandins and ATP. These substances were therefore assessed as possible inhibitory transmitters but further analysis with blocking drugs suggested that the relaxations produced by these drugs were different from that produced by the inhibitory nerves. The inhibitory effect of acetylcholine on the cat muscle was particularly interesting since it inhibited motor nerve responses as well as relaxing the muscle. Several substances not normally associated with release of noradrenaline from nerves, including guanethidine, cocaine LSD and 5HT produced indirect sympathomimetic effects in both species. (7) It is concluded that the anococcygeus muscle receives a dual innervation consisting of a motor adrenergic pathway originating from the lower thoracic and upper lumbar cord and a separate inhibitory pathway with its preganglionic fibres originating from the lower lumbar and upper sacral region of the vertebral column. This dual innervation is found in both the rat and cat anococcygeus but in neither species does the inhibitory pathway appear to be adrenergic, cholinergic or purinergic and the transmitter remains unknown.

Circulatory actions of phentolamine before and after autonomic blockade.

Abstract: Previous studies have suggested that phentolamine produces beta-adrenergic stimulation of the heart. We have defined the mechanisms by which this occurs by determining dose response curves to phentolamine before and after autonomic nervous system blockade with other drugs. Our studies demonstrate that the cardiac stimulation which results from phentolamine is reflexly induced by decreases in blood pressure and systemic vascular resistance.

Action of drugs on denervated myoepithelial cells of salivary glands

Abstract: 1. The pressure in the ducts of the two submaxillary glands was recorded in anaesthetized dogs in which either the superior cervical ganglion had been removed or the chorda-lingual nerve had been cut on one side, 17-30 days earlier. Noradrenaline, adrenaline, phenylephrine, acetylcholine and methacholine were injected to produce pressure rises attributed to contraction of myoepithelial cells. 2. After sympathectomy increased pressure responses were obtained with all the drugs, but particularly with noradrenaline. Cocaine increased the effect of noradrenaline on the normal gland but slightly less than sympathectomy. 3. Parasympathetic decentralization increased the pressure effects of acetylcholine and methacholine, and in most cases also increased those of the sympathomimetic drugs. 4. It is concluded that the myoepithelial cells of this gland normally receive motor impulses from both divisions of the autonomic nervous system, and that many, if not all, of the cells are innervated by both. Disconnecting the gland from the central nervous system by either pathway causes supersensitivity of the classical post-junctional type, and sympathetic ganglionectomy causes in addition a pre-junctional sensitization.

The role of the autonomic nervous system in the control of glucagon release during insulin hypoglycaemia in the calf

Abstract: Der durch Insulin herbeigefuhrte hypoglykamische Effekt wurde in Kalbern mit durchtrenntem Nervous splanchnicus durch Atropin verstarkt, wobei sich der Anstieg des Plasma-Glukagonwertes verzogerte und reduzierte. Es wird ein cholinergischer Mechanismus der Glukagonsekretion wahrend der Hypoglykamie vermutet.

Investigation of the behaviour of the autonomic nervous system under stress.

Abstract: of changes that take place in the HF ECG pattern with exercise in the single individual. A not dissimilar scheme can be applied clinically to detect presumed alterations in the myocardial state of the acute cardiac patient. By signal processing of the HF ECG, sufficient noise-reduction can be achieved to produce useful records in nearly all circumstances (even, in diagnostic testing, under exercise conditions). The new patterns are complex, but if the values of the HF ECG waveform are recorded in ranked sequence, a simple quantitative description of the sequence will characterize any changes in waveform as the patient recovers or deteriorates; hence a quantitative trend detection and evaluation procedure does exist. The interesting fact that the procedure now clearly warrants trial in exercisetesting for early coronary ischoemia is an illustration of the basic point that experience in computer processing of clinical signals may prove valuable in devising sensitive methods of health testing for early disease. So this second kind of computer-based signal manipulation leads back to the starting point of this Address. There are interesting and strategically important things to be done with the computer on the clinical signal; often these seek answers to specific questions about the individual patient, but underlying a significant number of these measurements is an attempt to look beyond the variable to the control system influencing it. Knowing about the state of the relevant control system in the body is an important first step to being able to manipulate it. In the meantime, while one cannot negotiate with a body control system, at least one can co-operate with it.

Evaluation of adaptation to the polar environment by autonomic nervous system responses

Abstract: Publisher Summary This chapter explores the adaptation to the polar environment by autonomic nervous system (ANS) responses. The studies carried out on different groups of people living in the Arctic showed that the problems of heat loss have importance with relation to nutrition and clothing. However, the stimulation of cutaneous receptors, principally of face and extremities, seems to be much more frequent. The chapter presents a study where most of the measurements were made when either the hand or the face were immersed into cold water at 4°C for two minutes. The pain sensation experienced with the hand immersion test coincided with the activation of the sympathetic nervous system (SNS), as seen by increased heart rate, increased vasoconstriction even in the opposite hand, and concomitant increase in blood pressure. The chapter presents a comparison between the hand and face immersion test, and it is shown that the increase in blood pressure was slightly greater with the face immersion test; this coincides with a somewhat greater pain sensation for most of the subjects.