Cholesteryl ester metabolism in fat- and cholesterol/fat-fed guinea pigs.

Guinea pigs were fed a semisynthetic diet containing 10% (by weight) cottonseed oil with or without 1% cholesterol. In response to cholesterol/fat feeding there was a significant accumulation of cholesteryl ester (CE), particularly in the liver, but also in the kidney, spleen and suprarenal glands. The hepatic acyl-CoA:cholesterol acyltransferase (ACAT) increased 5-10 times when the animals were fed cholesterol fat during 11 weeks while the acid cholesterol esterase (CE-ase) was similar in the two dietary groups. Intestinal lymph showed the highest content of cholesterol (both free and esterified) in guinea pigs fed cholesterol/fat. A low activity of lecithin:cholesterol acyltransferase (LCAT) was present in the intestinal lymph, irrespective of dietary composition. Triglyceride-rich lipoproteins seem to inhibit LCAT activity in the intestinal lymph. Plasma cholesterol levels in animals fed cholesterol/fat increased markedly while LCAT remained unaffected by the diets. Activity of ACAT and CE-ase in kidney and spleen was low compared to liver tissue and the enzyme activities were not affected by the cholesterol/fat feeding.