LIPOPROTEIN-LIPASE MASS AND ACTIVITY IN POSTHEPARIN PLASMA FROM SUBJECTS WITH INTRAABDOMINAL VISCERAL FAT ACCUMULATION

OBJECTIVES The purpose of this study was to investigate the possibilit y of impaired lipolysis of triglyceride-rich lipoproteins in patients with abdominal visceral fat accumulation by assessing two major lipoly tic enzymes in the plasma, lipoprotein lipase (LPL) and hepatic lipase (HL). DESIGN AND PATIENTS A total of 31 patients [20 men, 11 women, a ge 50 +/- 7 years old, body mass index (BMI) 26 +/- 2 kg/m(2) (mean +/ - sd)] were analyzed. Visceral fat and subcutaneous fat areas were eva luated using a computerized tomographic (CT) method at the level of th e umbilicus. Total lipolytic activity in the postheparin plasma (PHP) was measured using Triton X-100-emulsified triolein and LPL activity w as calculated as the activity in whole plasma inhibited by the 5D2 mon oclonal antibody for LPL. LPL enzyme mass was determined by a sandwich enzyme immunoassay. RESULTS The visceral fat area was found to be neg atively correlated with LPL mass (V vs LPL mass, r=-0.37, P=0.04) in P HP and had a tendency toward negative correlation with the LPL activit y in the PHP (V vs LPL activity, r=-0.29, P=0.12). Subcutaneous fat ar ea, on the other hand, did not show any correlation with LPL activity (r=0.13, P=0.49) or mass (r=0.22, P=0.25) in the PHP. The visceral fat area was found to be positively correlated with fasting serum insulin levels (r=0.67, P<0.01). Body mass index (BMI) was not correlated wit h LPL mass or activity in the PHP. Multi-regressional analysis showed that abdominal visceral fat could be correlated with LPL mass in the P HP, independently of fasting serum insulin. The HL activity from PHP o f the patients did not show significant correlation with visceral fat area, subcutaneous fat area or body mass index. CONCLUSIONS Fat distri bution affects LPL mass and activity, either directly or via another m etabolic abnormality such as insulin resistance, leading to impaired h ydrolysis of triglycerides in chylomicrons and very low density lipopr oteins (VLDL) in these subjects.