UDC

612.327:612.328:612.89

Authors

Sveshnikov Dmitry Sergeevich
Peoples’ Friendship University of Russia
8 Miklukho-Maklaya St., Moscow, 117198, Russian Federation;
e-mail: dmsveshnikov@gmail.com
Myasnikov Igor Leonidovich
Peoples’ Friendship University of Russia
8 Miklukho-Maklaya St., Moscow, 117198, Russian Federation;
e-mail: mil@mail.ru
Smirnov Viktor Mikhailovich
The Russian National Research Medical University named after N.I. Pirogov
1 Ostrovityanova St., Moscow, 117997, Russian Federation;
e-mail: vmsmirnov1@gmail.com
Torshin Vladimir Ivanovich
Peoples’ Friendship University of Russia
8 Miklukho-Maklaya St., Moscow, 117198, Russian Federation;
e-mail: V.I.Torshin@mail.ru

Abstract

The mechanism of enhancing gastric motility by electrical stimulation of sympathetic nerves was studied in acute experiments on dogs under general Nembutal anaesthesia (60 mg/kg, IM), right-sided thoracotomy, and artificial lung ventilation. The right sympathetic trunk was stimulated in the thoracic cavity, where it does not have vagus nerve branches. Contrary to our expectations, in most cases electrical stimulation of the sympathetic nerves did not cause inhibition but activation of gastric motility. This phenomenon complies with the power law: more stimuli caused more responses, reaching 90 % when 15V stimulus was applied, probably due to predominance of stimulatory fibres in comparison with adrenergic structures. Such a significant predominance of stimulatory responses over inhibitory ones during strong stimulation (10–15V) suggests lower excitability of the fibres of unknown nature (contained in the sympathetic trunk and stimulating gastric motility) compared to inhibitory adrenergic fibres. The research on the possible role of catecholamines in increasing gastric motility showed that blockade of adrenergic mechanisms does not eliminate the excitatory phenomenon but rather enhances motor responses of the stomach. Injection of sympatholytic and adrenoblocking agents improved both qualitative and quantitative parameters of motility: the share of stimulatory responses reached 100 %, while the hydrostatic pressure increased by the factor of 2.5–3 compared to the intact animals, indicating that catecholamines are not involved in the phenomenon under study. We found that this excitatory phenomenon is only eliminated by the blockade of 5-HT1,2 smooth muscle receptors by lysergol. We came to the conclusion that the sympathetic trunk contains serotoninergic fibres, which, in concert with the vagus nerve, under certain conditions are able to activate gastric motility.

Keywords

motor responses of the stomach, sympathetic nerves, sympathetic nervous system, 5-HT receptors, regulation

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