Tone of sympathetic nerves and regulation of heart activity

Tone of sympathetic nerves to the heart was studied in rats and guinea pigs. Experiments with pharmacological blockade of the sympathetic nervous system and vagotomy confirmed the general notion on the absence of tonic effects of sympathetic nerves on the heart. Reduction of the heart rate reported previously probably attests to various experimental designs (type and depth of anesthesia, possible hypothermia, duration of observations, and pharmacological preparations). As differentiated from the vascular tone, the heart rate under rest conditions depends on the vagal tone and circulating humoral substances. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 130, No. 10, pp. 370–373, October, 2000     

Shifts in cardiac indices induced by intravenous leu-enkephalin during sympathetic and parasympathetic blockade in rats

Effects of intravenous leu-enkephalin on heart rate, stroke volume, and minute blood volume under conditions of sympathetic and parasympathetic blockade were studied in experiments on pubertal rats anesthetized with urethane. This opioid peptide inhibits sympathetic and parasympathetic control on the heart, affecting not only chronotropic but inotropic cardiac indices. Translated fromByulleten' Eksperimental'noi Biologii I Meditsiny, Vol. 125, No. 6, pp. 623–625, June, 1998     

Differential activation of sympathetic nervous system and release of catecholamines during neuroglycopenia in awake rats

Neuroglycopenia induced by administration of 2-deoxy-d-glucose (125–375 mg/kg) is characterized by bradycardia and increased sympathetic activity, overall release of norepinephrine, plasma epinephrine, and norepinephrine at stable arterial pressure and norepinephrine plasmatic clearance. Sympathoneural activity is markedly enhanced in the adrenal-demedullated rats, while the levels of norepinephrine and its overall spill into circulation are the same as in the intact animals. It is concluded that neuroglycopenia is accompanied by differential activation of the sympathetic system subdivisions and selective release of norepinephrine by sympathetic terminals, but not by the adrenal medullae. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 124, No. 11, pp. 509–512, November, 1997     

Effects of leu-enkephalin and dalargin on cardiac function in rats under conditions of low-frequency stimulation of postganglionic sympathetic fibers

Leu-enkephalin inhibits and dalargin has no significant effect on the positive chronotropic effect of sympathetic stimulation. Both peptides potentiate the positive inotropic effect but do not change cardiac output. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 127, No. 2, pp. 140–143, February, 1999     

The sympathetic nervous system is not implicated in the development of vagotomy-induced tachycardia

It is believed by a number of investigators that vagal tone is weak and that tachycardia after bilateral vagotomy results from excitation of the sympathetic nervous system. However, this study shows that postvagotomy tachycardia develops without the participation of the sympathetic nervous system and decreases in the course of time spontaneously in animals with uninterrupted sympathetic nervous pathways. The degree of vagal tone is influenced by the type and depth of anesthesia. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 120, N ^o 8, pp. 125–128, August, 1995 Presented by K. V. Sudakov, Member of the Russian Academy of Medical Sciences     

Effect of vagotomy on heart rate in intact and sympathectomized rats of different ages

A comparative analysis of temporal variations of the heart rate variability after cutting and stimulation of the vagus in sympathectomized and intact rats showed that changes in heart rate after bilateral vagotomy in sympathectomized rats are opposite to those in the controls. It is postulated that postganglionic fibers modulate sympathetic influence on intracardiac parasympathetic neurons. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 124, No. 7, pp. 21–24, July, 1997     

Mechanism of enhanced gastric contractions in response to stimulation of the sympathetic trunk

Stimulation of the sympathetic trunk in the thoracic cavity of dogs was found to result, as a rule, in increased gastric contractions. The stimulatory effect was better defined in the presence of the drug Ornid but could be greatly decreased or completely eliminated by Promedol. It is suggested that the sympathetic trunk contains preganglionic serotoninergic nerve fibers which enhance gastric contractions. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 118, N^no 10, pp. 355–359, October, 1994 Presented by K. V. Sudakov, Member of the Russian Academy of Medical Sciences     

Adrenergic innervation of the gingiva in experimental periodontitis

In experiments on guinea pigs, the nerve-tissue relationships in gingival papillae were studied under conditions of experimental inflammation induced by local (turpentine injection) and general (whole-body γ-irradiation). It is found that structural and metabolic changes in the lamina propria and epithelium of the gingival mucosa correlate with disturbances in trophic influences from the sympathetic nervous system. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 127, No. 5, pp. 564–568, May, 1999     

Effect of vagal stimulation on cardiac rhythm in rats under blockade of β-adrenoreceptors by obsidan

Obsidan induced age-dependent bradycardia in intact rats and in rats with chemical sympathetic denervation. Subsequent vagal stimulation produced further decrease in heart rate. Administration of atropine to obsidan-treated rats increased heart rate. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 126, No. 12, pp. 612–614, December, 1998     

Role of σ-opiate receptors in development of ischemic arrhythmias

In acute experiments on anesthetized cats, the selective σ-opiate receptor agonist DSLET has a pronounced antiarrhythmic effect on ischemic heart rhythm disturbances. This effect is probably related to inhibition of the sympathetic heart rhythm regulation, because the antifibrillation effect of DSLET is not mediated via the vagus nerves, but on the other hand DSLET considerably modulates cardiac adrenoreactivity. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 127, No. 2, pp. 164–167, February, 1999.     

Implication of sympathetic innervation of the heart in antiarrhythmic action of intra-atrial laser irradiation

The role of sympathetic nervous system in the antiarrhythmic effect of intra-atrial laser irradiation (λ=632.8 nm) during myocardial ischemia was studied in acute experiments on Nembutal-anesthetized cats. Laser irradiation applied after bilateral, dextral, or sinistral transection of cardiac branches of stellate ganglia increased the number of ischemic rhythm disturbances that developed after occlusion of the circumflex branch of the left coronary artery. The maximum increase in the number of arrhythmias was observed after dextral transection, the occurrence of ventricular fibrillation being 100%. Bilateral transection provoked a larger number of ischemic rhythm disturbances than the sinistral transection. It is probable that the development of the antiarrhythmic effect of laser irradiation requires sustained sympathetic activity targeted at the nonischemic regions in the myocardium that could play a stabilizing role during local ischemic damage to the heart. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 126, No. 11, pp. 522–526, November, 1998     

A mechanism of antiarrhythmic effect ofRhodiola Rosea

It is shown that autonomic nervous system participates in the preventive antiarrhythmic effect ofRhodiola rosea. The effect of the preparation is presumably mediated through modulation of the sympathetic nervous system. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 125, No. 4, pp. 424–426, April, 1998     

Adrenergic control of production of humoral regulators of hemopoiesis in cytostatic myelodepression

It is established that the sympathetic nervous system controls the production of humoral regulators of hemopoiesis by bone marrow cells forming a hemopoiesis-inducing microenvironment in mice treated with 5-fluorouracil. The suppressive effect of catecholamines on the erythropoietic and colony-stimulating activities of the adhesive, nonadhesive, as well as the whole fraction of the bone marrow is shown using catecholamines and ganglioblocker in the period of restoration of hemopoiesis after cytostatic treatment. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 119, No. 2, pp. 135–140, February, 1995     

Mechanism of vagal inhibition of small intestine contraction

The mechanism of inhibition of small intestine contraction in response to weak stimulation of the peripheral end of the vagus nerve cut at the cervical level was studied in experiments on anesthetized dogs. This inhibition can be blocked with arfonade or hexamethonium, atropine, and rausedyl, as well as by combined, but not individual administration of propranolol and dihydroergotoxine. We assume that inhibition is triggered by the release of catecholamines from sympathetic postganglionic terminals in response to activation of their muscarinic receptors induced by acetylcholine released from parasympathetic terminals during excitation. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 129, No. 2, pp. 135–138, February, 2000     

Isolation from nervous effects: A mechanism of adaptation of biological systems to disease

A concept of functional isolation of the heart from nervous effects as a mechanism of heart adaptation to extreme states has been formulated. In moderate hypoxia, isolation of the cardiovasomotor center from nonhypoxic afferention provides the compliance of myocardial hyperfunction to the intensity of hypoxia and limits heart participation in different forms of activity of the organism. In thermal hypoxia, myocardial isolation from sympathetic and parasympathetic effects ensures its minimal function and economy of energy due to transfer to the autorhythmical mode of function and rules out heart participation in circulatory reactions. Functional isolation of the heart in hypoxia is caused by energy deficiency and depends on the training of an organism and coordination of the sympathetic and parasympathetic effects. High prevalence of isolation of cells, organs, and systems from regulating effects in health and disease is demonstrated and its mechanisms, levels, and impact are disclosed. Both the “extension” of nervous bonds and hyperfunction and the “narrowing” of nervous bonds and hypofunction of biological systems are aimed at adaptation of an organism. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 125, No. 6, pp. 604–611, June, 1998     

Neurotropic effect of myelopid on the motor activity of rats: Stereotypical movements,locomotion, and grooming

It is shown that myelopid, a new immunoregulating preparation isolated from bone marrow, modulates motor activity in rats and, consequently, possesses neurotropic activity. Presumably, the activating effect of myelopid on stereotypical movements is realized via stimulation of presynaptic receptors and subsequent activation of dopamine of the mesolimbic system, since this effect is abolished by the M-cholinoreceptor blocker atropine. The inhibitory effect on scratching may be a result of the inhibitory influence of myelopid on preganglionic sympathetic neurons of the spinal cord, since it was abolished by the blocker of ganglionic H-cholinoreceptors hexonium. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 118, N ^o 10, pp. 414–416, October, 1994 Presented by N. P. Bekhtereva, Member of the Russian Academy of Medical Sciences     

Effect of exogenous ATP on cardiac activity in rats

In vivo effects of exogenous ATP on cardiac activity were studied on adult rats. Intravenous administration of ATP produced a positive chronotropic effect, but did not affect the stroke volume. This was due to activation of type II purine receptors, rather than due to the influence of ATP hydrolysis products, since P1 receptor agonist adenosine was inefective. The blockade of β-adrenoceptors and muscarinic receptors did not modify the positive chronotropic effect of ATP, which indicated that this action was not realized via sympathetic or parasympathetic nerves. ATP applied against the background of atropine blocade produced a 4-fold increase in the variability of heart rate typical of activation of the parasympathetic myocardial regulation. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 129, No. 4, pp. 377–380, April, 2000     

New arguments for positive inotropic vagal influence on cardiac contractility in cats

Vagal influences on the heart were studied in narcotized cats, in which the cardiotripic effects of sympathetic nerves, heart rate, and pre- and afterload were excluded. Under these conditions vagus nerve exerted only a positive inotropic effect probably mediated by an unknown humoral factor. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 129, No. 4, pp. 396–398, April, 2000     

Dependence of autonomic and behavioral reactions to pain-related emotional stress on individual typological characteristics of the autonomic nervous system

It was found that autonomic and behavioral reactions to pain-related emotional stress in the miners of deep coal mines depend on the individual typological characteristics of their autonomic nervous system. The normotonics with an initially high sympathetic and parasympathetic activity were characterized by low resistance to stress-inducing factors, while high resistance to emotional stress was typical of the subjects with the parasympathetic type of autonomic nervous system. The greatest shifts in autonomic indices were observed in the stress-anticipation period rather than on direct exposure to pain stimulus. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 126, No 12, pp. 621–625, December, 1998