The effects of intravenously administered bombesin on pentagastrin-stimulated acid secretion in cats

Abstract

The effects of bombesin (BBS) infusion or BBS injection on the plateau gastric secretion stimulated by pentagastrin (Pg) were compared in cats fitted with gastric fistula (GF) and Heidenhain pouch (HP). Injection of 81 pmol/kg of BBS inhibited Pg-stimulated acid secretion in both GF and HP by 47 ± 5% and 37 ± 5% ( P < 0.01), respectively. Infusion of 324 pmol/kg · h of BBS did not significantly modify acid secretion, but as soon as the infusion stopped, an inhibition appeared which lasted 1 h (37 ± 5% in GF and 53 ± 4% in HP P < 0.01). The inhibition was reversed in GF by infusion of BBS 324 pmol/kg · h. In HP, reversion of inhibition required the addition in the Pg infusion of subthreshold dose of carbachol. We suggest that under non-steady state conditions (i.e. injection or after the end of the infusion) a concentration gradient of BBS is created which favors the response of D-cells over that of G-cells, whereas under steady-state conditions (i.e. during infusion) the effects of BBS on G- and D-cells are balanced. This finding argues for a physiological role of BBS in the regulation of gastric acid secretion.