IS ENDOTHELIAL FUNCTION OF THE RADIAL ARTERY ALTERED IN HUMAN ESSENTIAL-HYPERTENSION

There is controversy over whether endothelial function is impaired in human essential hypertension. All studies to date have used measuremen ts of forearm blood now by plethysmography to assess endothelium-depen dent vasodilation and endothelial function. In contrast to these studi es, which have focused on resistance vessels, we have determined what effects the endothelium has on underlying smooth muscle cells in condu it arteries by measuring arterial compliance of the radial arteries (c hange in diameter of radial artery over pressure for each arterial pul se). In 13 normotensive healthy subjects and 11 young patients with es sential hypertension, arterial compliance of the radial artery was ass essed directly with a new high-precision ultrasonic device (NIUS 02) a fter infusion of acetylcholine (endothelium-dependent response) or sod ium nitroprusside (endothelium-independent response). Arterial complia nce of the radial artery was similar at baseline and with increasing d oses of acetylcholine and sodium nitroprusside in normotensive and in hypertensive subjects. The increase in arterial compliance from baseli ne at each individual concentration of acetylcholine and sodium nitrop russide was the same in both normotensive and hypertensive subjects. H owever, after a single oral dose of a combination of the angiotensin c onverting enzyme inhibitor spirapril and the calcium entry blocker isr adipine, the increase in arterial compliance in response to the maximu m dose of intraarterial acetylcholine was enhanced in normotensives (0 .38 +/- 1.23 to 0.76 +/- 1.01 mm(2)/mm Hg x 10(-3), P < .05), but not in hypertensives (+0.41 +/- 1.26 to 0.36 +/- 1.31 mm(2)/mm Hg x 10(-3) , not significant), and differed significantly between normotensive an d hypertensive subjects (P < .05). Thus, pharmacologic stimulation dis closed a blunted response of endothelium-dependent action in the arter ial compliance of the conduit arteries in hypertensive subjects. This suggests an impaired endothelial function reserve in persons with esse ntial hypertension. (C) 1997 American Journal of Hypertension, Ltd.