Elevated serum gastrin after food intake or acid blockade evokes hypocalcemia.
Gastrin lowers blood Ca2+ in the rat. Recently, it was suggested that gastrin causes hypocalcemia by releasing gastrocalcin, a hypothetical peptide hormone thought to reside in the acid-producing part of the stomach. The results of the present study suggest that not only exogenous gastrin but also gastrin of endogenous origin lowers blood Ca2+. Food intake in fasted intact rats produced a transient drop in blood Ca2+, probably induced by the postprandial rise in serum gastrin. Food intake in fasted gastrectomized or fundectomized (acid-producing part extirpated) rats failed to induce any lowering of the blood Ca2+, supporting the view that the gastrin-evoked hypocalcemia is dependent upon a factor in the oxyntic mucosa. Also, the increase in serum gastrin concentration following intraperitoneal injection of the histamine H2-receptor antagonist ranitidine was associated with a drop in blood Ca2+ and also the ranitidine-evoked hypocalcemia could be prevented by gastrectomy. We suggest that endogenous gastrin evokes hypocalcemia by the same mechanism as exogenous gastrin, i.e., by mobilization of gastrocalcin from the acid-producing part of the stomach.
Håkanson
R
R
Department of Pharmacology, University of Lund, Sweden.
Persson
P
P
Axelson
J
J
D000818:Animals; D002118:Calcium / Q000097:blood*; D005502:Food; D005743:Gastrectomy; D005744:Gastric Acid / Q000502:physiology*; D005748:Gastric Fundus / Q000502:physiology / Q000601:surgery; D005755:Gastrins / Q000097:blood*; D008297:Male; D011899:Ranitidine / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains
D005755:Gastrins; D011899:Ranitidine; D002118:Calcium