Observations Concerning the Production and Excretion of Cholesterol in Mammals

Abstract

Intestinal lymph was collected from rats after acute ingestion of cholesterol and olive oil. The turbid lymphs were centrifuged to separate chylomicra, but insufficient to layer lipoproteins. Horizontal boundaries were obtained between the chylomicron layer and the faintly opalescent lower layer which facilitated the separate removal of each layer. Almost all the cholesterol and fat absorbed by the rat travels in the lymph chylomicron. Similar treatment of plasma obtained from normal rats during absorbtion of cholesterol and oil showed same encirclement of the chylomicronous layer with cholesterol and fat. No encirclement was noted in plasma or lymph from fasted animals. Plasma obtained from rats made chronically hyperlipemic by cholesterol and cholate feeding, or by injn. of anti-kidney serum, showed similar results. When chronic hypercholesteremia was induced by elevation of plasma cholate level, the serum remained clear and devoid of chylomicra and no encirclement of the upper layer was noted after centrifuging. A fundamental difference is suggested in transport of exogenous and endogenous cholesterol during the period of active absorbtion of cholesterol.