Changes in the gastric motility by the chemical and mechanical stimulations in the dog.

Abstract

The effects of chemical and mechanical stimulations on gastric motility was studied in 19 anesthetized dogs by using electromyographical techniques. The animals were fasted for 18 hr or more before each experiment. Six or eight bipolar silver-wire electrodes were implanted on a gastric wall serially from the fundus to the terminal antrum. At the pre-stimulation stage, the periodic simple electrical activity, which is called electrical control activity (ECA), was regularly recorded from the corpus to the antrum of the stomach; the frequency of which was 4.5 +/- 0.5 cycles/min on the average. Mechanical stimulation (distention of the stomach) decreased the ECA frequency depending on the degree of distention. The ECA frequency was decreased to 2.9 +/- 0.4 cycles/min by the 400 ml distention. Chemical stimulations to the gastric antral mucosa also decreased the ECA frequency depending on the strength of acidity or alkalinity. The instillation of a solution of pH 1 or 12.5 into the stomach decreased the ECA frequency to 3.4 +/- 0.7, and 3.5 +/- 0.5 cycles/min, respectively. A stronger alkaline solution induced anti-peristaltic discharges in 4 of 6 cases. The results indicate that both mechanical and chemical stimulations decrease the ECA frequency depending on stimulus strength.