Preparation, Assay, and Preliminary Characterization of Bovine Gastrin

Abstract

A gastrin-like gastric secretory stimulant was isolated by an alkaline extraction method from pyloric and fundic mucosae of the bovine abomasum. Secretory activity was measured after subcutaneous injection. The injected material was shown not to be histamine. The reaction to bovine gastrin is usually delayed for 60 to 90 min., in contrast with porcine gastrin, which reacts within 30 min., and with histamine, which reacts in even less time. The most active fractions of bovine gastrin were obtained by isoelectric precipitation at pH 3.0-4.0, in contrast with porcine gastrin, which has highest activity in the fraction precipitated at pH 5.0-5.5. The response to bovine gastrin, as is the case with the porcine material, persists for from 2 to 4 hr., contrasting with the speedy decline after response to histamine. In preliminary purification, we found a nondialyzable fraction, perhaps conjugated with or tenaciously held by a larger molecule, and a dialyzable fraction.