Relationship between cell size, plasma cholesterol and rat adipocyte cholesterol storage.

Plasma cholesterol and cholesterol storage/10(6) adipocytes were determined in the epididymal, perirenal, subcutaneous, and mesenteric fat depots of the fasted male rat. Adipocyte cholesterol increased exponentially as functions of mean cell diameter, body weight, and cell size (mug triacylglycerol/cell) in all depots examined, whereas plasma cholesterol was best described as a parabolic function of body weight. In all but the mesenteric depot, expression of storage as a ratio of cellular cholesterol:triacylglycerol was also described as a parabolic function of body weight, resulting in curves parallel to the cholesterol-body weight relationship. It is suggested that (1) adipose tissue cholesterol storage is most rapid after adipocyte number becomes fixed, (2) the level of cholesterol in the plasma may be a major determinant of fat cell cholesterol storage, especially in subcutaneous cells from adult animals in which cell size is constant but cholesterol storage continues to increase, and (3) the effect of plasma cholesterol is less pronounced in mesenteric adipocytes.