Effects of atropine on synthesis and secretion of pepsinogen in the rat

¹ Department of Medicine, Division of Gastroenterology, University of Alabama Medical Center, Birmingham, Alabama

Simultaneous measurements of gastric juice pepsin and stomach mucosal pepsinogen were made in groups of pylorus-ligated rats at intervals from 2 to 24 hours to examine the effects of atropine sulfate (20 mg/100 gm/8 hrs.) on pepsinogen secretion and synthesis. Animals given subcutaneous injections of water served as controls. Atropine caused a marked reduction in pepsinogen secretion and a concomitant accumulation of pepsinogen in the mucosa which increased with time to a plateau; pylorus ligation had the opposite effect, indicating that atropine effected the reduction in secretion of pepsinogen by blocking the release of pepsinogen from peptic cells. In untreated rats the hematocrit increased proportionately to presumed body water loss, but in the atropine-treated rats the hematocrit failed to increase to the same degree for equivalent body water loss. Indirect evidence is presented to suggest that the rate of water secretion may be one of the rate-limiting factors in pepsinogen secretion. Although synthesis of pepsinogen can proceed without secretion, correlation of the rates of synthesis with those of secretion suggested that the rate of synthesis could be increased by an increased rate of secretion.