In vivo study of cholesterol turnover in tissues of adult sows

The in vivo study of free and esterified cholesterol turnover was carried out in 15 tissues of adult Large White sows maintained at a constant weight for 10-12 weeks. They received a single intravenous injection either of [1-14C] acetate, or of an autologous red cell suspension or of plasma, previously labelled in vitro (for red cells) or in vivo (for plasma) with tritiated cholesterol. The tissues can be separated into four groups according to their relative rate of free cholesterol exchange between plasma and tissues. The liver and the lungs have a very fast exchange rate whereas the brain and the spinal cord have a very slow one. The whole lipoprotein particle transfer--an exclusive model for the esterified cholesterol transport from plasma to tissues--has been found in all sow tissues. When [1-14C] acetate is used as a substrate for cholesterol synthesis, lungs, adrenal glands and heart do not seem--or at an extremely low rate--to convert acetate into cholesterol whereas an intense cholesterol synthesis takes place in the small intestine. Its contribution to cholesterol synthesis in sows--taking into account the cholesterol transfer processes--reaches 70 per cent.