Correlation of endothelial function in large and small arteries in human essential hypertension.

Objectives The structure and function of blood vessels varies along the vas cular tree, and alterations found in hypertension are also different. The a im of this study was to determine whether non-invasive measurement of endot helial function in conduit arteries reflects that of subcutaneous resistanc e arteries measured in vitro. Methods and Results Sixteen essential hypertensive patients (aged 50 +/- 2 years) were studied. Plow-mediated dilation (FMD) during reactive hyperemia (endothelium-dependent) and sublingual nitroglycerin (NTG)-induced dilatat ion (endothelium-independent) were assessed in brachial arteries by ultraso und. Structure, and acetylcholine (10(-9) to 10(-4) mol/l) and sodium nitro prusside (SNP, 10(-8) to 10(-3) mol/l)-induced vasorelaxation of resistance arteries dissected from gluteal subcutaneous biopsies were measured in vit ro using a pressurized myograph. Brachial artery FMD and NTG-induced dilata tion were 8.4 +/- 1.0 and 18.1 +/- 1.4%, respectively. Resistance arteries of hypertensive patients showed greater media:lumen ratio (8.6 +/- 0.4 vers us 5.9 +/- 0.3% in normotensive subjects, P< 0.01), and maximal acetylcholi ne responses was diminished to 75 +/- 6% compared to normotensive subjects (97 +/- 2%, P< 0.01). FMD correlated with maximal acetylcholine responses ( r(2) = 0.57, P< 0.001). FMD did not correlate significantly with the media: lumen ratio of resistance arteries (r(2) = -0.22, P= 0.07). By multivariat e analysis, FMD predicted resistance artery endothelial function independen tly of age, sex, body mass index, blood lipid status and lumen diameter of brachial artery (<beta> = 0.81, p< 0.001). Conclusions Endothelial dilatory responses are similar in large and small a rteries in hypertensive patients. Abnormal FMD in the brachial artery predi cts the presence of endothelial dysfunction in human resistance arteries, s uggesting that impairment of endothelial function is a generalized alterati on in hypertension. Ultrasound measurement of endothelial dysfunction in th e brachial artery appears to be less sensitive than in-vitro measurement in resistance arteries. I Hypertens 19:415-420 (C) 2001 Lippincott Williams & Wilkins.