Variation in canine exocrine pancreatic secretory activity during the interdigestive state.

Interdigestive changes in pancreatic volume flow, gastric motor activity, and intraduodenal pH were monitored automatically in eight dogs. As a result, two different periods of pancreatic secretion were found to occur alternately during the interdigestive state: one a secretory period (2.2 +/- 0.32 ml/10 min with high protein and low bicarbonate concentration) and the other a nonsecretory period. The secretory period corresponded to the interdigestive phase II and III contraction period in the stomach, and the nonsecretory period coincided with the motor quiescent period in the stomach. However, another secretory period was identified during the interdigestive state; it occurred when the intraduodenal pH went below 7.0, and no typical interdigestive contractions were observed in the stomach. The secretory rate was 3.7 +/- 0.33 ml/10 min and was low in protein and high in bicarbonate concentration. The present study demonstrates that basal pancreatic secretory activity is never uniform but fluctuates with motor events in the stomach. However, its control mechanism remains unknown at present.