Effect of intrapulmonary heparin on lipoprotein lipase activity in mice.

The lipoprotein lipase (LPL) activity obtained from the intrapulmonary administration of 2-10 mg of heparin in mice was compared with the same parameter measured for intravenously administered heparin. The doses administered were based on appropriate clinical equivalents. A relatively large dose of intrapulmonary heparin produced a peak LPL activity which was a third of the maximum response obtained from a small dose of i.v. heparin. This was followed by a moderate LPL activity (twice the control level) which persisted for the next 4 days while the response obtained from i.v. administered heparin lasted only 2 h. Both the intrapulmonary and the i.v. administration of heparin produced dose-dependent increases in plasma LPL activity (correlation coefficient r = 0.9). This study indicates that intrapulmonary heparin causes a prolonged antilipemic effect.