Biomedical subjects
Publications and source records attributed to V M Smirnov.
We studied the influence of pretreatment with chemical mildronate analogue sibusol on the course of experimental gastric ulcer in rats. Sibusol produced a protective effects on the stomach and duodenum.
The mechanisms of stimulatory effect of the sympathetic trunk on gastric motor activity and vagal inhibitory effect on electromotor activity of the sphincter of Oddi were studied. Gastric contractions were augmented by preganglionic serotoninergic fibers related synaptically to serotoninergic neurons, while inhibition of electromotor activity of the sphincter of Oddi was elicited by activation of alpha- and beta-adrenoceptors.
The role of the lipid and phospholipid composition of tissue homogenates of the vagus nerve, cervicothoracic ganglion, heart, liver, erythrocytes and blood plasma of rabbits was studied in the synergism of vegetative nervous system parts. It was demonstrated that, when the vagus inhibition of the heart performance increased, the animals used to have a higher concentration of choline-containing phospholipids, and their erythrocyte membranes were more permeable.
It is a well-known fact that serotonin has a stimulative action on the motor-secretory activity of the gastrointestinal tract. Activation of 5HT3,4-receptors regulates neuronal responses of this action; it is possible to regulate efferent reactions by activating 5HT1,2-receptors (1, 2, 3). Carcinoid cells containing 5HT have 5HT3 and 5HT4 receptors on their superficial membranes. The object of this research was to determine the possible participation of serotonergic structures in the regulation of the jejunum motility.
The content of phospholipids in various tissues was studied during synergistic interaction between two branches of the autonomic nervous system. We found higher myocardial content of choline-containing phospholipids and lower rigidity of erythrocyte membranes in rabbits with pronounced sympathetic potentiation of the cardioinhibitory effect of the vagus nerve compared to rabbits without such potentiation.
We studied the mechanisms of opposite effects of sympathetic and parasympathetic nervous systems on gastric motility. The involvement of serotoninergic structures in the realization of the stimulatory effect of the sympathetic trunk on gastric motility and the role of adrenergic intramural ganglia in vagal inhibition of electrical and motor activities of the antrum were demonstrated.
The authors studied the mechanism of the higher vagus suppression of cardiac performance, which occurs when irritation of the sympathetic nerve is added to that of the vagus and when gastric motility occurring with the irritation of the sympathetic trunk is stimulated. Preganglionic serotonic fibers synaptically connected with serotoninergic intramural neurons are involved in showing these mechanisms.
The mechanisms of interactions between various compartments of the autonomic nervous system were evaluated by studying sympathetic potentiation of vagal cardioinhibitory action. It was found that this effect is realized through preganglionic serotoninergic nerve fibers making synaptic contacts with intracardiac serotoninergic neurons. Our results indicate that cardiac activity is modulated by the vagus nerve and serotoninergic nerve fibers of the sympathetic nerve acting synergistically.
A significant delay in benz(A)pyrene-induced tumorigenesis was obtained following three series of parenteral injection of xenogenic leukocytic interferon alternating with irradiation at 3-4 day intervals. Radiation was delivered from a red low-energy laser through a puncture in the peritoneal wall of the spleen. When each of said procedures was performed separately similar effects were recorded but the changes were not significant.
Explored was mechanism of inhibition of small intestine contractions due to weak irritation (0.5-2.5 V, 1-30 Hz, 0.3-1.0 ms) of the peripheral segment of rabbit's right vagus nerve. It was shown that the inhibitory effect can be blocked by benzohexamethonium, arphonade, atropine, rhausedyl, and a combination of propranolol and dehydroergotoxine. Inhibition is triggered by catecholamines released by sympathetic endings in consequence of activation of presynaptic M-cholinoreceptors on their surface. Presynaptic M-cholinoreceptors are activated by acetylcholine released by the endings of postganglionary parasympathetic nerve fibers.
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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.
Acute experiments with dogs showed that irritation of the sympathetic trunk in the thoracic cavity is more likely to amplify than inhibit duodenal contractions. This stimulating effect is better seen with alpha- and beta-adrenoreceptors blocked by phentolamine hydrochloride and inderal and cannot be eliminated with dizergol used to block S1,2 receptors of the cellular membranes in smooth muscles. On the evidence and literary data it was deduced that the sympathetic trunk contains some serotoninergic nervous fibers potent to stimulate contractions of the duodenum.
Stimulation of the sympathetic stem chest portion induces enhancement rather than suppression of gastric contractions. The activating effect is more obvious under conditions of the alpha- and beta-adrenoreceptors blockade with phenolamine and obsidan, and eliminated with the smooth muscle serotoninoreceptors blocking agent lisergol. The findings suggest that the sympathetic stem includes some serotoninergic neural fibres exerting a strong effect upon gastric and intestinal contractions. A previously unknown serotoninergic part of the vegetative nervous system controlling the internal organs functions, seems to exist in the organism.
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Experiments on pigeons, guinea pigs, rats, cats, rabbits, and dogs showed that tachycardia occurring after ligation of vagus nerves was caused by dissection of their inhibitory tone. They failed to confirm the hypothesis of the sympathetic origin of vagotomic tachycardia. The vagus nerve through the cholinergic neurons may exert heterodirectional (inhibitory and stimulating) effects on the performance of the heart only in animals with its tone. In the absence of tone, there may be only inhibition and stimulation was only short-term as a result of cessation of the inhibitory effect--postvagal tachycardia. The earlier established idea of the inhibitory tone of the vagus nerve remains valid.
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