Cholesterol homeostasis in the guinea pig. The importance of quantitating net tissue accumulation of cholesterol in sterol balance studies.

Sterol balance measurements of whole body cholesterol synthesis were performed in guinea pigs to determine the relative quantitative importance of dietary cholesterol intake, endogenous cholesterol synthesis, fecal steroid excretion and net tissue accumulation in cholesterol homeostasis of a rapidly growing animal. Sterol inputs were from diet (33%) and endogenous synthesis (67%); sterol outputs, as fecal neutral and acidic steroids, accounted for 60% of the total input, the remainder being used for the demands of tissue growth. The data demonstrate that the measurement of total body cholesterol synthesis can be grossly underestimated in this rapidly growing animal if net tissue accumulation of cholesterol is not considered in the balance measurement.