CALCIUM-ABSORPTION IN RATS WITH DISTAL INTESTINAL RESECTION - INFLUENCE OF TYPE OF DIETARY-FAT, CHOLECALCIFEROL AND NATURE OF THE ADAPTATIVE RESPONSE

The effects of dietary and supplementation with cholecalciferol on cal cium absorption at different luminal concentrations (2.07 mmol/l and 2 .07 mmol/l with 0.5 mmol/l 2,4-dinitrophenol and 8.20 mmol/l) were stu died in vivo in the perfused duodenum, residual jejunum and proximal c olon of rats with resection of 50% of the distal small intestine, as w ell as the nature of the adaptative response (passive or active). Chan ging the source of dietary fat (diet B, containing 1/3 medium chain tr iglycerides, 1/3 olive oil, 1/3 sunflower oil) increased calcium absor ption, preferentially via active transport, in both transected and res ected rats. Supplementation of diet B with cholecalciferol further enh anced intestinal calcium absorption, especially in the colon. These re sults suggest the importance of diet in the adaptive processes and con firm that active mechanisms of transport adapt more readily to intesti nal resection than do passive mechanisms.