Lipoprotein lipase activity of adult rat cardiocytes

Cardiocytes were prepared by enzymatic dissociation of adult rat ventricular tissue, and comparative studies on lipoprotein lipase activity were conducted on fresh homogenates and acetone powders of these cells. Lipolytic activity in fresh homogenates was largely dependent on addition of serum activator to the assay, and the activity was sensitive to 1 M NaCl. Lipoprotein lipase activity was maximized in acetone powder preparations of cardiocytes. Approx. 10% of the total lipolytic activity was extractable from acetone powders of cells homogenized in the absence of serum, while approx. 50% was soluble from powders of cells homogenized with 10% serum. The non-extractable lipolytic activity was inhibited 80% with 1 M NaCl and about 47% with antibodies (IgG) to heart lipoprotein lipase. The buffer-extracted enzyme was completely sensitive to NaCl and was inhibited 80% by low concentrations of anti-lipoprotein lipase antibodies.