CONTINUOUS INTRAVENOUS HEPARIN ADMINISTRATION IN HUMANS CAUSES A DECREASE IN SERUM LIPOLYTIC-ACTIVITY AND ACCUMULATION OF CHYLOMICRONS IN CIRCULATION

Heparin is a well-known, widely used anticoagulant drug. In addition t o its anticoagulant properties, however, it also has a marked influenc e on fat metabolism Postprandial lipoproteins may contribute significa ntly to the development of coronary heart disease. Therefore, it is im portant to evaluate the effects of heparin on these lipoproteins. The effect of continuous heparin administration on postprandial lipoprotei n metabolism was studied in 11 patients with thromboembolic disease. R esults were compared with those in a group of six patients given no he parin. Two vitamin A-fat loading tests were done: the first, 5 days be fore heparin was started and the second, on the fourth day of continuo us heparin drip of 1000 U/h, maintaining PTT levels at twice the basel ine. To study the effect of acute heparin, an additional fat loading t est was done in five patients on the first day of heparin treatment. V itamin A specifically labels intestinally derived lipoproteins with re tinyl palmitate (RP). The concentrations of chylomicron (S-f > 1000)- and nonchylomicron (S-f < 1000)-retinyl palmitate were measured for 10 h postprandially. Four days of continuous intravenous heparin adminis tration increased the area below the chylomicron RP curve from 11091 /- 4393 to 17684 +/- 5949 mu g/l . h (P < 0.003). When measured on the first day of heparin treatment in five patients, the area of the chyl omicron fraction was reduced from 16678 +/- 6895 to 10474 +/- 3893 mu g/l . h (P < 0.05). Postheparin lipoprotein lipase activity was signif icantly lower on the fourth day of heparin administration than before treatment: 1.8 +/- 1.1 vs. 4.1 +/- 1.3 mu mol/FFA per ml per h, respec tively (P < 0.0005). In the six control patients with thromboembolic d isease in whom heparin therapy was not indicated, no changes in postpr andial lipoprotein levels or in lipolytic activity during hospitalizat ion were found. The study demonstrates that 4 days of heparin administ ration causes an accumulation of chylomicrons in the circulation, most probably as a result of a marked decrease in serum lipolytic activity . - Weintraub, M., T. Rassin, S. Eisenberg, Y. Ringel, I, Grosskopf, A . Iaina, G. Charach, M. Liron, and A. Rubinstein. Continuous intraveno us heparin administration in humans causes a decrease in serum lipolyt ic activity and accumulation of chylomicrons in circulation.