Characterization of the lipoprotein lipase in the functional pool of rat heart by immunoblotting

Rat hearts were perfused with heparin for 2 min at 4°C. The lipoprotein lipase activity in the perfusate was inhibited by antiserum to rat adipose tissue lipoprotein lipase. By immunoblotting, the lipoprotein lipase derived from the functional pool of the heart was found to be a protein with an apparent M r of 69000. After incubation of the perfusate at 37°C for 24 h an immunologically reactive protein with an apparent M r of 28000 was found. This protein is not a physiological derivative of the enzyme but a degradation product.