1,2-3-H cholesterol as a tracer in studies of human cholesterol metabolism.

1,2-(3)H-Cholesterol was fed to a subject together with 4-(14)C-cholesterol at a known (3)H/(14)C ratio. The ratio was satisfactorily preserved in cholesterol recovered from plasma, red cells, and bile, and in bile acids of bile. Isotopic fractionation was seen during thin-layer chromatographic isolation of cholesterol. In work with 1,2-(3)H-cholesterol or its metabolites care should be taken to recover chromatographic bands in their entirety.