Influence of hypocholesterolemic drugs on aortic cholesterol esterase in rabbits.

We have studied the influence of three hypocholesterolemic drugs (Fenofibrate, Pirinixil and Probucol) on aortic cholesterol esterase (E.C.3.1.1.13) activity in cholesterol-fed rabbits. After three weeks, cholesterol-fed controls exhibited a 28% increase in cholesteryl ester synthetase activity (S) and a 13% decrease in cholesteryl ester hydrolase activity (H) giving a 47% increase in S/H ratio. None of the drugs influenced cholesterol-induced synthetase activity, but fenofibrate treatment increased hydrolase activity resulting in a fall in the S/H ratio to the level observed in rabbits fed corn oil but no cholesterol. The other two hypocholesterolemic agents did not affect the aortic S/H ratio.