Molecular forms of gastrin in antral mucosa, plasma and gastric juice during vagal stimulation of anesthetized cats

Gastrin was released by electrical vagal stimulation in anesthetized cats. Antral mucosa, blood and gastric juice samples collected during vagal stimulation were subjected to gel filtration in order to characterize the different molecular forms of gastrin. In antral mucosa component III (gastrin-17) predominated. Besides, the antrum contained 5 per cent component II (gastrin-34, "big" gastrin), 1 per cent component I and trace amounts of component IV (gastrin-14 or "mini" gastrin). Immediately after vagal stimulation, component III (gastrin-17) appeared in the gastric venous effluent followed within a few minutes by component IV (gastrin-14). Component I and II (gastrin-34) were not detectable in any of the plasma samples. We suggest that component III (gastrin-17) is released from the antral mucosa and is then rapidly metabolized to component IV (gastrin-14) possibly to a significant extent in the fundic region of the stomach. Large amounts of component III (gastrin-17) were found in the vagally-induced gastric juice. Only very small amounts of degradation products were present, indicating that cat gastrin is relatively resistant to peptic degradation and acid hydrolysis.