[Mono- or biphasic release of gastrin. Results after isolated antrum perfusion in vitro]

In an in vivo preparation, isolated rat antra were perfused with different releasing agents in an oxygenated Krebs-Ringer-A solution. Upon perfusion with acetylcholine (+ 0,1 mM eserine), the mean gastrin levels in the effluent increased within 2 min to 4 times the basal level, while there was a smaller second release after 20 min. During perfusion with 50 mM glycine and 30 mM calcium chloride containing Krebs-Ringer-A solution gastrin levels in the effluent increased within 4 min to twice the basal level without a secondary release of gastrin. Perfusion with eserine alone or with Krebs-Ringer-A solution failed to release gastrin. The apparent biphasic release of gastrin with acetylcholine may suggest that antral gastrin may exist in two different populations, one of which is readily accessible, the other less so. Alternatively, the initial peak may consist only of stored gastrin and the second peak of newly synthesized gastrin, stimulated only by the physiologic stimulus of acetylcholine, and not by other releasers.