The Liver and Postheparin Plasma Lipolytic Activity in Dog and Man.

The intravascular injection of heparin results in the rapid appearance in the blood of a lipolytic enzyme capable of clearing lipemic sera and hydrolyzing artificial triglyceride emulsions (1, 2). This enzyme has been termed clearing factor (3), lipoprotein lipase (4), clearing factor lipase (2), or postheparin plasma lipolytic activity (PHLA) (5). A lipolytic enzyme with characteristics nearly identical to those of PHLA has been identified in relatively high concentration in tissue extracts of heart (4), adipose tissue (6), and mammary gland (7, 8). Lower concentrations of this lipolytic enzyme have been found in tissue extracts of thoracic and abdominal viscera, including the liver (3, 4, 9). Release of PHLA from tissue sources into the circulation has been demonstrated in perfusion studies of limbs and abdominothoracic viscera (3, 10, 11). However, perfusion of the isolated rat liver with heparinized blood has been reported by several observers (10, 12-14) to result in net loss of PHLA and no release of lipolytic activity by the liver. Boberg, Carlson, and Normell (15), on the other hand, have reported recently in an abstract that the isolated perfused canine liver