Small intestinal mucosal hyperplasia caused by an enterokinase inhibitor from red kidney bean in rats.

A specific enterokinase inhibitor (EKI) was purified from red kidney bean (RKB). Male weanling rats fed a diet containing this purified EKI (0.06%) for 6 d showed increases in mucosal weights, protein, DNA and lactic dehydrogenase contents in their small intestines compared to age-matched control rats fed a standard diet. Total mucosal EK and disaccharidase activities were, however, decreased in EKI-fed rats. Thus, oral consumption of EKI from RKB led to small intestinal mucosal hyperplasia in rats. The mucosal hyperplasia observed in EKI-fed rats is not likely due to decreased turnover of mucosal proteins as a result of reduced luminal proteases since luminal contents of trypsin, chymotrypsin and elastase in EKI-fed rats were similar to those of control rats. Enterokinase inhibitor may have a direct hyperplastic effect on the small intestine of rats.