Lipoprotein lipase activity in human heart

¹ Department of Medicine, University of Washington, Seattle, Washington

Human ventricular tissue was obtained 11–28 hr post mortem, homogenized in ammonium hydroxide, and tested for its ability to catalyze the hydrolysis of an "activated" cottonseed oil emulsion. Lipolysis, as indicated by a rise in fatty acids, occurred in the presence of a freshly prepared homogenate, but not in the presence of a boiled homogenate. Sodium chloride, 1 m, inhibited the reaction, but sodium fluoride, 0.2 m, did not. An activated cottonseed oil emulsion was more readily hydrolyzed than a "nonactivated" cottonseed oil emulsion. Approximately 50% of the activity of the homogenate sedimented at a gravitational force produced by centrifugation at 800 g for 10 min. The conclusion is that human heart tissue, like animal heart, contains lipoprotein lipase activity and that this activity is associated, in part, with the heavier cellular particles.