Effect of carbachol on vascular and luminal release of immunoreactive gastrin from isolated perfused rat duodenum

The release of intestinal gastrin was examined using the isolated vascularly and luminally perfused rat duodenum. Results show that duodenal gastrin was released into both the intestinal lumen and circulation. The basal release of immunoreactive gastrin (IRG) into the lumen was 23.3 +/- 1.8 pg/min and that into the vasculature was 70.1 +/- 8.2 pg/min. The administration of 1 microM carbachol into the vascular perfusate resulted in a marked reduction of luminal release of IRG; however, vascular release of IRG was not affected. The carbachol-induced inhibition of luminal release of IRG was blocked by atropine but not by hexamethonium. These data suggest that only the luminal release of IRG from the rat duodenum, but not vascular release of IRG, is under the inhibitory control of the cholinergic muscarinic mechanism.