Electrical arrhythmias in gastric antrum of the dog.

Antral electrical arrhythmias were investigated in 32 unanesthetized chronic dog preparations implanted with serosal electrodes and transducers. Five of these animals underwent surgical removal of the duodenal cap and the adjacent hypomuscular segment. In the intact dogs two distinct types of arrhythmias of the basic electric rhythm (BER) were observed. During phase I (basal activity) arrhythmias were recorded in 17 of 32 dogs. In 9 of the 32 dogs, arrhythmias were present in more than 10% of recorded phase I activity. These arrhythmias included tachygastria as well as mixed gastric rhythms. A second type of arrhythmia consisting of premature and delayed BER occurred in all dogs during phase III (burst activity). In all five dogs, duodenal cap removal produced a marked increase in antral arrhythmias as well as the disruption of normal interdigestive motor and electrical patterns. The changes in terminal antral electrical rhythmicity after surgery may be due to an interaction with the higher frequency duodenal pacemaker tissue. Antral frequencies of 15-18 cycles/min in two of five dogs several days after cap removal were evidence of a duodenal influence. Antral arrhythmias may be present during both normal and pathophysiological states. Their importance is as an indicator of the functional status of the antral smooth muscle and its responsiveness to normal physiological and pharmacologic stimuli.