ADIPOSE-TISSUE LIPOPROTEIN-LIPASE AND HORMONE-SENSITIVE LIPASE - CONTRASTING FINDINGS IN FAMILIAL COMBINED HYPERLIPIDEMIA AND INSULIN-RESISTANCE SYNDROME

The metabolism of free fatty acids (FFA) is altered in two common athe rosclerosis-promoting disorders: familial combined hyperlipidemia (FCH L) and insulin resistance syndrome (IRS). It has been suggested that t hese two conditions may have a common etiology. The enzymes lipoprotei n lipase (LPL) and hormone-sensitive lipase (HSL) are rate-limiting st eps for the turnover of fatty acids in adipose tissue, because they hy drolyze extracellular triglycerides in lipoproteins (LPL) and intracel lular triglycerides in adipocytes (HSL). The present study was underta ken to simultaneously determine the activities of LPL and HSL in subcu taneous adipose tissue from male patients with FCHL and IRS. LPL and H SL activity was investigated in 10 nonobese FCHL patients and compared with 10 matched healthy nonobese subjects, and in 8 essentially normo lipidemic IRS patients (who did not have overt diabetes mellitus) and compared with 9 nonobese matched control subjects. LPL activity was 43 % lower in patients with IRS (P<.0005), as compared with control subje cts, but HSL activity was not significantly different in the two group s. On the other hand, HSL activity was decreased by 45% in FCHL patien ts (P<.01), as compared with control subjects, but LPL activity was no t significantly different in FCHL patients and the control group. In c onclusion, triglyceride metabolism in adipose tissue is altered in bot h FCHL and IRS. However, the abnormalities observed involve impaired f unction of LPL in IRS and impaired function of HSL in FCHL, suggesting separate etiologies for the altered lipolysis in these conditions, at least in male subjects.