The significance of changes in tissue clearing-factor lipase activity in relation to the lipaemia of pregnancy

Abstract

The concentration of tri-glyceride fatty acid [TFA] in the plasma of the pregnant rat rises to a maximum 2-4 days before parturition. Thereafter there is a rapid delince in the concentration to near normal values at parturition. A similar increase occurs in animals fed on a diet low in fat. There is no increase in food consumption at the time when the TFA concentration in the plasma is at its peak. Rates of entry of TFA into the blood during pregnancy were estimated from the rate of accumulation of triglyceride in the plasma of animals injected with a non-ionic detergent, Triton. A progressive increase occurs in the entry rate as the body weight increases throughout pregnancy. Expressed per constant body weight, the entry rate does not change significantly. Adipose-tissue clearing-factor lipase activity is low at the time when the plasma triglyceride fatty acid concentration is raised. Activity of the enzyme in heart, lung and diaphragm is unchanged. It is suggested that the ''lipemia of pregnancy'' may be due to diminished uptake of TFA by adipose tissue, and, further, that the disappearance of the lipemia may be due to increased uptake of TFA by the mammary gland.