Effect of intestinal bypass on cholesterol absorption and blood levels in the rabbit

Abstract

A chronic in vivo preparation for the study of cholesterol absorption is described. Ten rabbits which had undergone ileocecal valvuloplasty, ten rabbits subsequent to upper small intestinal bypass and ileocecal valvuloplasty, and ten rabbits with lower small intestinal bypass (including the ileocecal valve), are compared to ten normal controls, on the basis of blood radioactivity, and whole blood cholesterol levels, following a force-fed standard test dose of cholesterol-4-C¹⁴, 10 mg, 0.4 µc/mg. The conclusions arrived at from the data are that the entire small intestine is capable of absorbing cholesterol, that bypass of either the upper or the lower half of the small intestine results in a marked (> 80%) reduction in the blood radioactivity subsequent to the oral test dose, and that there is a functional difference between the upper and the lower small intestinal bypass groups. Transit time in the small intestine appears to play a major role in the amount of cholesterol absorbed. To achieve both a marked lowering of cholesterol absorption and circulating cholesterol levels, the most efficacious surgical site of bypass of the small intestine is the ileum.