Mechanism of Gastric Motor Reactions Caused by Sympathetic Nerve Irritation

Abstract

In acute experiments on dogs performed under the surgical stage of nembutal anesthesia (60 mg / kg, i/m), right-sided thoracotomy, and artificial ventilation, the mechanism of increased gastric contractions that occur when the right sympathetic trunk is irritated in the thoracic cavity, where it does not contain anastomoses with a vagus nerve, was studied. It was found that in the vast majority of cases, irritation of the sympathetic trunk causes not depression, but increased contractions of the stomach. This phenomenon obeys the law of force relations: with an increase in the stimulus amplitude, the number of stimulatory responses increases, reaching 90 % with a 15 V stimulus, which may indicate a quantitative predominance of fibers that stimulate gastric contractions over inhibitory structures of an adrenergic nature. A significant predominance of the number of stimulatory reactions over inhibitory ones under severe irritation (10-15 V) suggests a lower excitability of fibers of unknown nature (they are part of the sympathetic trunk and stimulate gastric motility) compared to inhibitory adrenergic fibers. The study of the possible role of catecholamines in increasing gastric contractions showed that the blockade of adrenergic mechanisms not only does not eliminate the stimulatory phenomenon, but, on the contrary, contributes to the manifestation of stimulatory reactions.