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Biomedical subjects

O A Shevelev

Publications and source records attributed to O A Shevelev.

31 records · Page 2Linked to original sources
PubMed1987

[Mechanisms of cutaneous-cardial interconnections].

Using the method of double stimuli, some features of inhibitory influences of conditioning stimulation of cutaneous zones on the afferent transmission from the heart were studied in the experiments on cats. It has been shown that when the interval between testing and conditioning stimuli is from 50 to 150 ms, the cutaneous stimulations effectively block the appearance of evoked potentials in the rostral parts of the cerebral cortex, which were induced by the electrical stimulation of the sinoatrial nodal zone. Bilateral vagotomy completely eliminated this reaction. Stimulation of the peripheral part of the cut vagus also effectively blocked the transmission of the afferent impulses from the heart. It was concluded that inhibitory cutaneo-cardiac effects are determined by the mechanisms of presynaptic inhibition, which develop at the level of intracardiac nervous system.

Animals↗
PubMed1987

[Afferentation of the heart in pathological states of the myocardium].

The state of afferent connections between sinoatrial node zone (SNZ) in the normal and affected myocardium (reversible ischemia, necrosis) and rostral parts of the brain cortex (RPC) was studied with the help of evoked potentials in acute experiments on cats. Interruption of afferent connections (SNZ-RPC) during reversible ischemia and experimental myocardial necrosis of the right ventricle was revealed. Ultramicroscopic data of SNZ studies as well as electrophysiologic changes registered in RCP during irritation of the peripheral part of the right vagus nerve and local application of GABA on SNZ suggest possible interruption of cardiac afferentation at the level of SNZ due to the mechanism of presynaptic inhibition.

Afferent Pathways↗
PubMed1986

[Effect of alcohol on conduction of afferent impulsation from the area of the sinus node of the heart to structures of the central nervous system].

Acute experiments in cats, using the induced potentials technique, showed intraperitoneal 30% alcohol administration (1.5-2 ml per 1 kg body weight) as well as direct application of 2 or 3 ml of similarly concentrated alcohol solution to the sinus node area (SNA) to block afferent impulse conduction from the SNA to central nervous structures, such as cerebral cortex, reticular formation of the midbrain, peri-aqueduct gray matter. The fact that the induced potentials generated within the cerebral cortex and subcortical structures in response to SNA stimulation showed a pattern of change that was similar to the one associated with alcohol administered intraperitoneally or applied directly to SNA has suggested that alcohol may block the cardiac afferent flow directly at the level of SNA structures.

Animals↗
PubMed1985

[Cortical representation of the heart sinus node zone].

Evoked potentials (EP) arising in response to electrical stimulation of the heart sinus node zone (SNZ) were registered in the cortex of the large hemispheres (LHS) of cats. EP with the shortest latent period (LP) of 18-19 months were recorded both in the left and right hemispheres in the area of a cross-shaped cleft (associative field PCA, partially the I motorsensor zone and the I sensorimotor zone). Besides, EP with a more durable LP (20-21 months) were registered in the 2nd sensorimotor zone. EP remained unchanged after bilateral vagotomy and disappeared after spinal cord cutting at C-2 level. The presence of the functional centre regulating cardiac activity in the branch sections of LHS is suggested.

Animals↗
PubMedDate not supplied

[Comprehensive investigation of hemodynamics in normalcy and in complete transverse blockade].

Acute experiments were conducted on 75 dogs for complex study of central hemodynamics and the pumping and contractile activity of an intact and altered myocardium by means of an automated system of computer treatment of the data of synchronous monitoring suggested by the authors. It is shown that the development of cardiac insufficiency in complete atrioventricular block is determined by deep desynchronism of performance of the parts of the heart, which is characterized by essential changes of the parameters of myocardial working capacity and hemodynamics and by radical shifts in normal correlative relations. The growing deficit of blood supply is compensated for by myocardial hyperfunction: a relatively small (up to 20%) increase of the capacity of the left parts is attended by a more than double increase of the capacity of the right parts.

Animals↗
PubMedDate not supplied

[The characteristics of the modulation of afferent reactions by adrenergic and cholinergic preparations and by the electrostimulation of the skin under conditions of changing atmospheric pressure].

The authors studied the organism's afferent reactions in changing conditions of atmospheric pressure in electrostimulation of skin zones during application of adren- and cholinergic agents. All of the studied adren- and cholinolytic agents facilitated the inhibition of afferent reactions, in contrast to mediation intensifying agents. The results of the experiments suggest that the nociceptive thresholds at atmospheric pressure of 550 mm Hg reduce, which may be linked with intensification of the catecholamine reactions of the organism of untrained animals. This is confirmed by the results of experiments with inderal injection, in which the effect of inhibition of the induced afferentation is most marked at pressure of 550 and 360 mm Hg. Besides, the analgesic activity of benactyzine diminished under similar conditions. Inderal and benactyzine potentiate the analgesic effect of percutaneous electroneurostimulation.

Afferent Pathways↗
PubMedDate not supplied

[Features of the modulation of afferent reactions by agonists and antagonists of opiate receptors and competitive stimulation of the skin under conditions of changing barometric pressure].

Afferent body reactions were studied under conditions of changes of atmospheric pressure in electrostimulation of skin zones and use of various agonists and antagonists of opiate receptors. The results suggest maintenance of a sufficiently high therapeutic efficacy of transcutaneous electrostimulation at levels of up to 5.5 km above sea level and emphasize the leading role of endogenous ligands of opiate receptors in realization of the analgesic effects of competitive skin stimulation. The results of the study also provide evidence of a high analgesic activity of dalargin, a synthetic analogue of leu-enkephalin, which persisted at a height of up to 7.5 km above sea level. Increasing the resistance of the experimental animals to acute high-altitude hypoxia, this agent facilitates the development of analgesic reactions in electrostimulation of the skin.

Afferent Pathways↗
PubMedDate not supplied

[Effect of an acute lesion on afferent reactions of the stomach and duodenum].

By recording the evoked potentials in the cortex and thalamic nuclei, afferent reactions of gastroduodenal components were studied early after acute gastroduodenal lesion in acute feline experiments. A model of acute ulcer in various gastric portions and the duodenal bulb gave rise to inhibition of their afferentation. This phenomenon was most pronounced in pyloric ulcer. It is concluded that the inhibition of the afferent reactions of gastroduodenal components in early periods after their acute lesion is a specific protective reaction of the viscera and appears mainly at the intraorgan level.

Acute Disease↗
PubMedDate not supplied

[Effect of electric stimulation of the cerebral cortex on cardiac nociceptive signal conduction].

In acute experiments on cats we studied the influence of the cortex cerebri electric stimulation on potentials in the subcortical structures such as the thalamus, hypothalamus, striatum griseum superficiale. The potentials were provoked by electric irritation of the nodus synuatrialis zone of the heart conducting system. A cortex cerebri depressing effect (mainly the 1st and 2nd zones of somatovisceral sensitivity) on cardiac afferent signals with nociceptive component was determined.

Animals↗