Biosynthetic origin of serum cholesterol in the squirrel monkey: evidence for a contribution by the intestinal wall.

The possibility that the intestinal wall serves as a biosynthetic site for serum cholesterol has been examined in two types of studies in the squirrel monkey. First, animals were fed cholesterol in order to inhibit cholesterol synthesis in the liver, and the intestinal lymph ducts were cannulated. After the administration of acetate-2-(14)C it was possible to demonstrate that cholesterol synthesized by the intestinal wall enters intestinal lymph and thereby in the intact animal enters the circulating pool. Second, an attempt to quantitate the significance of this intestinal contribution has been made in animals fed cholesterol-3-(3)H and injected with cholesterol-4-(14)C for long periods. By an application of the technique of analysis utilizing the isotopic steady state we estimated as a minimal value that in the squirrel monkey 1.5-2.0 mg of cholesterol synthesized in the intestinal wall reaches the circulation each day.