Pancreatic enzyme secretion produced in the rat by trypsin inhibitors

¹ Department of Nutritional Sciences, University of California, Berkeley, California

In previous experiments, rats fed soybean trypsin inhibitor exhibited an exaggerated secretion of principal pancreatic digestive enzymes, as measured by the enzyme activities of the pancreas and intestine shortly after feeding. The present experiments studied the effect of trypsin inhibitors from egg white and lima bean on this pancreatic response in the rat. The influence of atropine and bilateral vagotomy on such secretion was also investigated. Both egg white and lima bean trypsin inhibitors evoked pancreatic enzyme secretion similar to that produced by soybean trypsin inhibitor. Inactivation of the inhibitors by reaction with crystalline trypsin prior to feeding did not impair the response. The physiological activity of these substances appeared to be closely associated with their trypsin inhibitor activity, yet inactivation of endogenous trypsin in the small intestine seemed not to be necessary for the response. Although vagotomy or a parasympathetic blocking agent did not suppress the pancreatic response to soybean trypsin inhibitor, no evidence for the release of a humoral factor by the inhibitor was obtained by cross-circulation observations.