Pure human minigastrin: secretory potency and disappearance rate.

Minigastrin, a gastrin with 13 amino-acid residues, was recently isolated from tissues by Gregory and Tracy (1974). In this study, pure human natural nonsulphated minigastrin (HG-13-I) and pure human natural nonsulphated heptadecapeptide gastrin (HG-17-I) were compared with regard to acid-stimulating potency and rate of disappearance from blood. Three dogs with gastric fistulae and Heidenhain pouches were given these gastrins by continuous intravenous infusion in doses of 100, 200, 400, and 800 pmol/kg-hr. Equimolar infusion rates of HG-13-I and HG-17-I caused equimolar increases over basal of serum immunoreactive gastrin but HG-13-I- was less than half as potent as HG-17-I in stimulating acid secretion (potency ratio 0.4, 95% confidence limits 0.2 to 0.6). The half time for disappearance of HG-13-I from blood was 1.8 minutes and its volume of distribution was calculated to be 0.17 1/kg, values similar to those found for HG-17-I in an earlier study. The role of minigastrin in health and disease awaits further study.