Importance of muscle lipoprotein lipase in rats during suckling.

Abstract

In order to evaluate the relative importance of groups of tissues containing lipoprotein lipase (LPL) in the removal of serum triacylglycerols during development, LPL activity was determined in cardiac and skeletal muscle, brown (BAT) and white adipose tissue (WAT), lung and kidney of rats aged 0-60 days, either fed or fasted for 6 h. On fasting, LPL activity did not change in lung and kidney, decreased in WAT except at 14 days and to a lesser extent in BAT, whereas muscle LPL decreased at 0, 3, and 7 days and increased from 14 days onward. The fasting-induced changes in serum triacylglycerol concentrations in suckling pups could be attributed to corresponding changes in muscle LPL. In the adult, the main contributor to total LPL activity was WAT in fed rats and muscle in fasted rats, as expected. In suckling pups, however, muscle LPL contributed 63-85% of the total and WAT less than 25%, whatever the nutritional state. The results strongly suggest that clearing of circulating chylomicrons during suckling largely depends on muscle LPL.