Effects of hydrocortisone and pentagastrin on the activity of intestinal disaccharidases and alkaline phosphatase in weanling rats.

Effect of bilateral adrenalectomy and subsequent injections of hydrocortisone and pentagastrin on the activity of different intestinal digestive enzymes were measured in 20-day-old rats. Eleven days after adrenalectomy the activity of lactase, sucrase, and alkaline phosphatase, but not maltase, was significantly decreased when compared with sham-operated rats. In adrenalectomized rats, repeated injections of hydrocortisone (50 mg/kg) significantly increased the activity of lactase, sucrase, maltase, and alkaline phosphatase by 15%, 49%, 32% and 121%, respectively, over the corresponding adrenalectomized control. Pentagastrin (500 microgram/kg) injections to adrenalectomized rats produced significant 41% and 58% increments in lactase and alkaline phosphatase activities, compared with the adrenalectomized control. Sucrase activity was unaffected by pentagastrin, but maltase showed a non-significant 34% higher activity than in the adrenalectomized control. Adrenalectomy by itself lowered the Km and Vmax of alkaline phosphatase by 33% and 66%, respectively, which were increased to 95% and 70% of the corresponding sham-operated level by either hydrocortisone or pentagastrin treatment. When intestinal homogenates from salinetreated adrenalectomized rats were mixed in equal proportion with homogenates from sham-operated or hydrocortisone- or pentagastrin-treated animals, Km values for alkaline phosphatase were found to be similar to those observed for sham-operated or hormone-treated groups alone. However, in the same mixed preparations Vmax values were found to be additive.