Characterization of lipoprotein lipase activity in the newborn rat liver

Acetone ether powders of livers from starved newborn rats were applied to heparin-Sepharose affinity columns. The so-called hepatic triacylglycerol lipase was eluted with 0.9 M NaCl and a second lipolytic activity peak was eluted with 1.5 M NaCl. The behaviour of this 1.5 M NaCl-eluted fraction against increasing concentrations of serum, NaCl, protamine sulfate and heparin in the assay mixture was almost identical to that shown by partially purified lipoprotein lipase from adult rat adipose tissue, and clearly different from that shown by partially purified hepatic triacylglycerol lipase from the adult rat liver. We conclude that the newborn rat liver contains a lipoprotein lipase activity with similar properties to those found in adult adipose tissue lipoprotein lipase activity. It is suggested that this enzyme enables the neonatal liver to take up circulating triacylglycerols directly.