In vitro esterification of cholesterol by plasma: the effect of evisceration*†

The capacity of plasma of eviscerated rats to esterify free cholesterol was compared with that of plasma of normal control rats by incubating the plasma of these rats with free cholesterol-4-C14 dispersed on Celite and by determining the percentage of labeled sterol in the esterified form at the end of 18 hr. Cholesterol esterification was severely restricted in incubation mixtures prepared with plasma of the eviscerated rats. The restriction could not be accounted for by the presence of inhibitors nor by the absence of heat-stable activators. On the basis of these as well as other observations, it is concluded that the reduced capacity of the plasma of eviscerated rats to esterify cholesterol resulted from removal of the source (probably the liver) of the plasma enzyme or of heat-labile cofactors responsible for the esterification, or both.