Age-related reduction of NO availability and oxidative stress in humans.
Age-related endothelial dysfunction could be caused by an alteration in the L-arginine-NO system and the production of oxidative stress in both normotensive and hypertensive individuals. In 47 normotensive subjects and 49 patients with essential hypertension, we evaluated forearm blood flow (by strain-gauge plethysmography) modifications induced by intrabrachial sodium nitroprusside (1, 2, and 4 microg/100 mL per minute) and acetylcholine (0.15, 0.45, 1.5, 4.5, and 15 microg/100 mL per minute), an endothelium-independent vasodilator and an endothelium-dependent vasodilator, respectively. Acetylcholine was repeated in the presence of the NO synthase inhibitor N(G)-monomethyl-L-arginine (L-NMMA, 100 microg/100 mL per minute), the antioxidant vitamin C (8 mg/100 mL per minute), or both. Vasodilation to acetylcholine, but not to sodium nitroprusside, was lower (P<0.01) in hypertensive patients compared with control subjects. Moreover, in both groups, endothelium-dependent vasodilation declined with aging. In normotensive subjects, the inhibiting effect of L-NMMA on response to acetylcholine decreased in parallel with advancing age, whereas vitamin C increased vasodilation to acetylcholine in only the oldest group (age >60 years). In young hypertensive patients (age <30 years), vasodilation to acetylcholine was sensitive to L-NMMA, whereas in hypertensive patients age >30 years, vitamin C enhanced endothelium-dependent vasodilation and restored the inhibiting effect of L-NMMA on response to acetylcholine. In normotensive individuals, an earlier primary dysfunction of the NO system and a later production of oxidative stress cause age-related reduction in endothelium-dependent vasodilation. These alterations are similar but anticipated in hypertensive patients compared with normotensive subjects.
Taddei
S
S
Department of Internal Medicine, University of Pisa, Pisa, Italy. s.taddei@int.med.unipi.itqq
Virdis
A
A
Ghiadoni
L
L
Salvetti
G
G
Bernini
G
G
Magagna
A
A
Salvetti
A
A
D000109:Acetylcholine / Q000494:pharmacology; D000328:Adult; D000367:Age Factors; D000368:Aged; D001205:Ascorbic Acid / Q000494:pharmacology; D004336:Drug Antagonism; D004730:Endothelium, Vascular / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D005542:Forearm / Q000098:blood supply; D006801:Humans; D006973:Hypertension / Q000209:etiology* / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000096:biosynthesis*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D009599:Nitroprusside / Q000494:pharmacology; D018384:Oxidative Stress; D012039:Regional Blood Flow / Q000187:drug effects; D014664:Vasodilation / Q000187:drug effects; D014665:Vasodilator Agents / Q000494:pharmacology; D019323:omega-N-Methylarginine / Q000494:pharmacology
D004791:Enzyme Inhibitors; D014665:Vasodilator Agents; D009599:Nitroprusside; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D000109:Acetylcholine; D001205:Ascorbic Acid