Differences in heparin-released lipolytic activity in the superficial and deep veins of the human forearm

Various doses of heparin were given as a single injection into the brachial artery of each of twelve fasting healthy males. Plasma lipolytic activity was measured in samples obtained before and at frequent time intervals after heparin injection, in the artery and the deep and superficial veins of the same forearm. As little as 0.15 U heparin produced a rapid and detectable release of lipolytic activity in both deep and superficial veins. A series of tenfold increases in the dose produced correspondingly greater releases in the veins but the increments in the release were smaller than the increments in the dose. Three repeated 15 U doses of heparin, separated by 30 min, in the same subject gave a high degree of reproducibility of the release of lipolytic activity in both deep and superficial veins. 90% of the lipase activity in the vein was inhibited by 1 M NaCl. In all subjects the release of lipolytic activity was higher in the deep vein, which predominantly drains muscle, than in the superficial vein, which drains mostly subcutaneous tissues such as skin and adipose tissue. This indicates that muscle is a tissue of considerable importance as a source of post heparin plasma lipolytic activity.