Gastroenterology
-
Intraduodenal infusion of 0.05-0.5 N hydrochloric acid dose-dependently increases serum levels of immunoreactive gastric inhibitory polypeptide (GIP) in rats. Immunoreactive GIP released by duodenal acidification is biologically active because it augments the glucose-induced release of immunoreactive insulin (IRI). This augmentation of glucose-induced IRI release by intraduodenal acid can be abolished for 30 min by simultaneous intravenous infusion of GIP-antiserum. ⋯ The GIP release is a direct effect of intraduodenal acid and is not mediated via secretin release. Injection of secretin in supraphysiologic doses does not change serum levels of immunoreactive GIP. However, such secretin injections induce a short-term insulin release and a decrease in serum glucose concentration.