Effects of carbachol and atropine on gastrin secretion and synthesis in rat antral organ culture.

The purpose of the present study was to examine the effects of the cholinergic agent carbachol on gastrin synthesis and secretion by rat antral mucosa in organ culture. In addition, the effect of atropine on basal and carbachol-stimulated gastrin release was investigated. These in vitro studies demonstrate that carbachol stimulated both gastrin secretion and synthesis in a dose-dependent manner. Maximal stimulation of gastrin synthesis and release occurred at a concentration of 1 X 10(-5) M carbachol. The rate of gastrin release stimulated by carbachol (1 X10(-5) M) was 0.79 ng-hr-1-mg-1 which was significantly greater than the control value of 0.37 ng-hr-1 (P less than 0.001). Atropine, over the dose range from 10(-7) to 10(-3) M, had no effect on basal (unstimulated) gastrin release. However, carbachol-stimulated gastrin release was inhibited progressively by inclusion of increasing concentrations of atropine in the culture media. The results of these studies indicated that the acetylcholine analogue, carbachol, is capable of directly stimulating the antral gastrin cell to significantly increase the rate of synthesis and release of gastrin. Whereas atropine, under these in vitro conditions, does not alter basal gastrin release, the muscarinic antagonist does competively inhibit carbachol-stimulated gastrin secretion.