Plasma lipoprotein lipase after subcutaneous heparin.

IN ADDITION to its anticoagulant action, heparin initiates the release of lipoprotein lipase into the blood. This lipolytic enzyme has the capacity to reduce the turbidity of lipemic plasma and hence has become known also as "clearing factor." Its clearing action occurs from the hydrolysis of triglyceride contained in chylomicrons and other lipoprotein particles.' Studies in animals have suggested that the administration of heparin inhibited the development of atherosclerosis.2-4 Heparin may block atherogenesis because of its antilipemic property. Heparin has been used in the treatment of patients with coronary atherosclerosis because of these effects on lipid metabolism.5-7 Lipoprotein lipase resulting from the injection of heparin reduces lipemia8 and thereby may inhibit atheroma formation. It is known that this enzyme appears in the blood promptly after the intravenous injection of heparin and begins to disappear rapidly.9 In order to obtain more prolonged activity, heparin has been given by subcutaneous injection. The present investigation was undertaken to find out how long lipoprotein lipase remained in the blood of men after the administration of subcutaneous and intravenous heparin. If the use of heparin in the therapy of atherosclerosis is predicated on its antilipemic action, then it would seem of some importance to show the particular dose as well as the route of administration that can be expected to produce significant and prolonged plasma lipoprotein-lipase activity. The influ-