Endothelial dysfunction in resistance arteries is related to high blood pressure and circulating low density lipoproteins in previously treated hypertension

Background: Peripheral endothelial dysfunction has been demonstrated in hyp ertension. However, its relationship to blood pressure (BP) load, vascular structure, and metabolic disturbances in patients with long-standing, previ ously treated hypertension is unclear. Methods: A total of 41 patients with stage I to III essential hypertension and electrocardiographic left ventricular hypertrophy were studied. After 2 to 3 weeks of placebo treatment we measured nitroprusside-induced relaxati on (NIR), acetylcholine-induced relaxation (AIR), and media:lumen ratio in isolated, subcutaneous resistance arteries by myography, as well as 24-h am bulatory BP, and serum lipids. Results: Maximal AIR correlated negatively with median 24-h diastolic BP (r = -0.42, P =.01), and sensitivity to AIR correlated negatively with serum low density lipoprotein (LDL) (r = -0.36, P < .05). In multiple regression analyses, sensitivity to AIR correlated negatively with serum LDL (beta = - 0.33) independently of maximal NIR (beta = 0.41) (adjusted R-2 = 0.26, P < .01). Maximal acetylcholine-induced relaxation correlated negatively with m edian 24-h diastolic BP (r = -0.38) independently of maximal NIR (beta = 0. 45) (adjusted R2 = 0.32, P < .001). Acetylcholine-induced relaxation was no t significantly related to diabetes or to media:lumen ratio (r = -0.26, NS) . Conclusions: High diastolic BP and high serum LDL were associated with impa ired maximal AIR and reduced sensitivity to AIR, respectively, independentl y of smooth muscle cell responsiveness to nitroprusside. This indicated dec reasing endothelial function in small resistance arteries with increasing B P and increasing LDL in hypertension. Endothelial function was not signific antly related to vascular structure of the resistance arteries or to diabet es in these patients with long-standing hypertension. (C) 2001 American Jou rnal of Hypertension, Ltd.