Effect of intraantral pH on basal gastrin release into the circulation and antral lumen in anesthetized cats.

In acute experiments on cats antral pouches were perfused with solutions of different pH (1-13). After antrum passage the gastrin levels in the perfusates were measured with radioimmunoassay and the amounts of gastrin released into the antral lumen per minute calculated. The venous gastrin levels were determined concomitantly. Small amounts of gastrin (1,000--1,500 pg/min) were released into the antrum during perfusion with 0.1 M HCl. Subsequent perfusion with 0.15 M NaCl (pH 6.8) did not significantly increase the release of gastrin. On the other hand, 0.1 M phosphate buffer (pH 7.4) caused a dramatic augmentation of the gastrin output into the antral lumen (approximately 17 fold). A concomitant increase of peripheral gastrin levels was observed. Also other alkaline solutions such as 0.15 M NaHCO3 (pH 8), 0.15 M Tris buffer (pH) or 0.01 and 0.1 M NaOH (pH 12 and 13) promoted the release of gastrin. It is discussed whether the gastrin release at alkaline pH is induced by the alkaline pH itself or by anions such as HPO-4, HCO-3 and OH-. The apparent effect of pH could then be due to the formation of these ions at higher pH.