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Does lipoprotein(a) impair endothelial function?

Abstract：

OBJECTIVES:This study was undertaken to test the hypothesis that lipoprotein(a) [Lp(a)] impairs endothelial function. BACKGROUND:Elevated Lp(a) plasma levels have been demonstrated to be associated with an increased risk of coronary heart disease. In atherosclerosis, endothelial dysfunction is known to be an early indicator of vascular changes. However, the effect of Lp(a) on nitric oxide (NO)-dependent vasodilator response has not yet been determined. We therefore examined the influence of Lp(a) on basal and stimulated NO-mediated vasodilator response in the forearm vascular bed. METHODS:Strain gauge plethysmography was used to measure changes in forearm blood flow produced by intraarterial infusion of increasing doses of acetylcholine (3, 12, 24 and 48 microg/min), sodium nitroprusside (200, 800 and 3,200 ng/min) and N-monomethyl L-arginine (L-NMMA) (1, 2 and 4 micromol/min) in 57 white subjects (mean age +/- SD 37 +/- 14 years). Lp(a) plasma concentrations were determined by rocket immunoelectrophoresis. RESULTS:Endothelium-dependent vasodilation tested by intraarterial acetylcholine and endothelium-independent vascular relaxation tested by intraarterial sodium nitroprusside were not correlated with Lp(a). Similarly, no significant differences in forearm blood flow changes were observed when patients were classified into tertiles according to their individual Lp(a) concentration. In contrast, changes in forearm blood flow after intraarterial L-NMMA indicating basal production and release of NO differed significantly among tertiles. Patients in the highest Lp(a) tertile (49.2 +/- 20.3 mg/dl) had a much greater vasoconstrictive response to L-NMMA than patients in the lowest Lp(a) tertile (4.8 +/- 2.5 mg/dl): 2 micromol/min of L-NMMA, -23.6 +/- 22.5% vs. -10.4 +/- 9.1% (p < 0.02); 4 micromol/min of L-NMMA, -27.8 +/- 10.3% vs. -17.6 +/- 9.9% (p < 0.03). Lp(a) plasma level consistently correlated negatively with the forearm blood flow responses to 4 micromol/min of intraarterial L-NMMA (r = -0.38, p < 0.01). Multiple stepwise regression analysis of variables, including total and high and low density lipoprotein cholesterol, further confirmed that plasma Lp(a) remained a significant independent determinant of forearm blood flow changes in response to L-NMMA (p < 0.02). CONCLUSIONS:The endothelium-dependent vasoconstrictive response to L-NMMA was enhanced in subjects with relatively high Lp(a) plasma levels, suggesting an increased basal production and release of NO. This response seemed to reflect a compensatory mechanism of the endothelium to yet unknown Lp(a)-induced atherosclerotic effects.

journal_name

J Am Coll Cardiol

journal_title

Journal of the American College of Cardiology

authors

Schlaich MP,John S,Langenfeld MR,Lackner KJ,Schmitz G,Schmieder RE

doi

10.1016/s0735-1097(97)00497-x

subject

Has Abstract

pub_date

1998-02-01 00:00:00

pages

359-65

issue

eissn

0735-1097

issn

1558-3597

pii

S0735-1097(97)00497-X

journal_volume

pub_type

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Does lipoprotein(a) impair endothelial function?