ENDOTHELIAL FUNCTION IN SUBCUTANEOUS RESISTANCE ARTERIES FROM ELDERLYHYPERTENSIVE AND NORMOTENSIVE SUBJECTS

1. Previous studies have indicated that younger hypertensive subjects may have abnormal endothelium-dependent relaxation, which could contri bute to the elevated peripheral resistance seen in established hyperte nsion, This study was designed to examine the functional behaviour of the endothelium of small arteries from elderly hypertensive and normot ensive subjects. 2. Resistance arteries were obtained from gluteal bio psies taken under local anaesthesia in 28 subjects of mean age 70 (ran ge 60-76) years, and studied in an isometric myograph. Eighteen subjec ts had untreated essential hypertension, and 10 were normotensive. 3. After measurement of the contractile response to noradrenaline, relaxa tion responses to a variety of endothelium-dependent (acetylcholine an d bradykinin) and endothelium-independent (iloprost and sodium nitropr usside) mechanisms were assessed in vessels precontracted with noradre naline. Endothelium-dependent responses were also studied after incuba tion with N-G-nitro-L-arginine to inhibit nitric oxide synthase. 4. Th ere were no significant differences in the contraction or relaxation r esponses between elderly subjects with or without high blood pressure. Inhibition of nitric oxide synthase prevented any relaxation with ace tylcholine and significantly attenuated the relaxation with bradykinin . Near-complete relaxation was however achieved with the endothelium-i ndependent vasodilator sodium nitroprusside. 5. Hypertension in elderl y subjects is not associated with a reduction in endothelial vasodilat ing function in the subcutaneous vessels of the gluteal region compare d with age-matched normotensive controls. The results of this study do not support the hypothesis of a defect of resistance artery endotheli um-dependent relaxation in the pathophysiology of hypertension in the elderly.