Early Change of Specific Activity of Plasma and Red Blood Cell Cholesterol following Intravenous Administration of [4- 14 C]Cholesterol in Man 1

Abstract

Summary

The tracer [4-¹⁴C]cholesterol, incubated at 37° for 1 hr with the subject's own plasma, was administered intravenously to two subjects. The initial rapid decrease of plasma cholesterol specific activity indicated a net disappearance of [4-¹⁴C]cholesterol from the bloodstream, presumably due to phagocytosis of the particu-late cholesterol by the reticuloendothelial system. The initially disappeared [4-¹⁴C]cholesterol quickly reappeared in the blood. Complete equilibrium between RBC and plasma-free cholesterol was attained within 12-18 hr, whereas the equilibrium between plasma-free and esterified cholesterol required 2 days. Therefore, the com-partmental analysis should be based on the plasma total cholesterol specific activity obtained 2 days after the injection.