Endothelial vasodilatory function is predicted by circulating apolipoprotein B and HDL in healthy humans

Endothelium-dependent vasodilation (EDV), LDL particle size, and antibodies against oxidized LDL (oxLDLab) have been shown to be related to the development of atherosclerosis and cardiovascular disease. In this study, we investigated whether LDL particle size, oxLDLab, apolipoproteins, and lipoproteins are related to endothelial vasodilatory function in a population sample of 58 apparently healthy subjects aged 20 to 69 yr. EDV and endothelium-independent vasodilation (EIDV) were studied in the forearm during local administration of methacholine chloride (2 and 4 microg/min) or sodium nitroprusside (5 and 10 microg/min). Forearm blood flow was determined with venous occlusion plethysmography. In multiple stepwise regression analyses, neither oxLDLab nor small LDL particles were significantly predictive of endothelial vasodilatory function. Instead, a high level of apolipoprotein B (apoB) was an independent predictor of both attenuated EDV and EIDV (r = -0.43, P < 0.01, and r = -0.34, P < 0.05, respectively). HDL cholesterol, on the other hand, was the only lipid variable that was significantly related to the EDV to EIDV ratio, an index of endothelial vasodilatory function (r = 0.35, P < 0.01). The inverse associations between apoB and both EDV and EIDV indicate that apoB might be an early marker of structural vascular changes in healthy subjects, whereas HDL seems to be more specifically related to endothelial vasodilatory function.