Influence of dietary status and diabetes on aortic acyl-CoA hydrolase activity

We have postulated that the accelerated snythesis of cholesteryl ester in atherosclerotic microsomes may result in part from decreased acyl-CoA hydrolase activity in arterial tissue, because acyl-CoA is a common substrate for both reactions. We have now investigated the influence of nutritional status, type of diet, and diabetes on the acyl-CoA hydrolase activity of otherwise normal aortic microsomes. Fasting rabbits for 16 hr diminished the acyl-CoA hydrolase activity approximately 30%. The activity of this aortic microsomal enzyme in rats maintained on a high-carbohydrate diet for 5 weeks was comparable to the activity observed on a high fat (olive oil) diet. The type of fat in the diet influences the acyl-CoA hydrolase activity: oils containing 77% oleic acid (high-oleic safflower oil) and containing 70% linoleic acid (conventional safflower oil) lowered the aortic microsomal acyl-CoA hydrolase activity in comparison to a more saturated fat (cocoa butter). Aortic preparations of rats made diabetic by streptozotocin exhibited higher acyl-CoA hydrolase activity than the normal. The results show that conditions associated with human atherogenesis (diabetes and saturated fat diet) increase rather than suppress the activity of this arterial enzyme in normal arterial tissues of the rat.