Effect of chyme on mucosal enzyme levels in small intestine of the rat

Partial jejunectomies, gastrojejunostomies (with closed pylorus), and jejunal Thiry-Vella loops were made in order to elucidate the role of chyme in the control of mucosal mass and the activities of alkaline phosphatase, ATPase, and maltase in the small intestine of the rat. After partial jejunectomy, a partially reversible mucosal hyperplasia was seen in the small intestine with the exception of distal ileum. After gastrojejunostomy a similar hyperplasia took place in the jejunum and proximal ileum. In the jejunal Thiry-Vella loops a mucosal atrophy was found in 4 wk. After partial jejunectomy the activity of alkaline phosphatase decreased slowly in 4 wk in the remaining small intestine with the duodenum as an exception. ATPase activity decreased in the duodenum. Maltase activity remained unchanged during 8 postoperative wk. In gastrojejunostomized rats the activity of alkaline phosphatase and ATPase increased slowly during 12 wk in the jejunum aborally from the gastroenterostomy. A slight depression of maltase activity was observed in the operation area and a slight increase of enzyme activity was found in the middle of the small intestine. In jejunal Thiry-Vella loops the activity of alkaline phosphatase decreased, but no change of maltase activity could be observed during 4 wk. Perfusion of a loop with maltose solution did not cause any changes in the activity of alkaline phosphatase or maltase. The results indicate that after a change in chyme passage the adaptation takes place in the small intestine primarily by the change of mucosal mass, and at least some enzyme levels in the mucosal cells are remarkably stable.