Resection of rabbit ileum: effect on brush border membrane enzyme markers and lipids

Alterations in transport function have been described 6 weeks after surgical resection of 50% of the distal small intestine. Previous studies demonstrated a modest increase in the jejunal uptake of medium chain length fatty acids following resection, while the uptake of many other lipids (cholesterol, bile acids, fatty alcohols, short and long chain length fatty acids) appears to be unaffected. Marked changes in the kinetic constants for the carrier-mediated uptake of four sugars and leucine were observed following resection, but the changes in transport were not associated with changes in the mucosal surface area. This study was undertaken to examine the possible adaptive mechanisms that occur with ileal resection in the rabbit. A 29% increase in the wet weight of jejunal mucosal scrapings and a 53% increase in jejunal brush border membrane (BBM) protein was observed following resection. The jejunal BBM sucrase (S) was unchanged following ileal resection, but alkaline phosphatase (AP) total activities were increased in the resected rabbits. This resulted in a 45% increase in the ratio of AP/S with resection. The lipid composition (total free fatty acids, total bile acids, total cholesterol, total phospholipids, individual phospholipids, and the ratio of total phospholipids/total cholesterol) of BBM was similar in control and resected rabbits. This suggests that quantitative rather than qualitative changes in the membrane composition may be responsible for the transport changes observed in resected animals.