Abnormal post-heparin lipolytic activity in obesity. A preliminary note.

Published data have suggested that hypertriglyceridemia in obesity may result from the combination of hepatic overproduction and diminished removal of triglyceride-rich lipoproteins. Diminished catabolism might be expected if tissue lipoprotein lipase activity were decreased, a finding which has been reported in biopsies of adipose tissue from obese subjects. Abnormalities in heparin-released triglyceride lipase activity (PHLA) in obesity have not been reported, however. We have examined the possibility that methods for the measurement of PHLA might have failed to reveal such a defect because of the disproportionality between plasma volume and increasing body mass in obesity. Since it is usual to administer heparin on the basis of body weight, higher plasma heparin levels would be achieved in obese individuals. We performed standard PHLA assays in lean and obese volunteers. In the obese, heparin levels were consistently higher than in lean individuals although PHLA values were similar in both. Thus, PHLA in obesity appeared to be inappropriate for the heparin levels attained in plasma. Pharmacokinetic studies suggest that a decrease in PHLA available for release by heparin rather than heparin insensitivity underlies this phenomenon.