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

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Abstract
The effects of chemical and mechanical stimulations on gastric motility was studied in 19 anesthetized dogs by using EMG techniques. The animals were fasted for 18 h or more before each experiment. Six or 8 bipolar Ag-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 c/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 antiperistaltic discharges in 4 of 6 cases. Both mechanical and chemical stimulations decrease the ECA frequency depending on stimulus strength.