Large elastic artery compliance is reduced and arterial blood pressure (BP) is increased in the central (cardiothoracic) circulation with aging. Reactive oxygen species may tonically modulate central arterial compliance and BP in humans, and oxidative stress may contribute to adverse changes with aging. If so, antioxidant administration may have beneficial effects. Young (Y; 26 +/- 1 yr, mean +/- SE) and older (O; 63 +/- 2 yr, mean +/- SE) healthy men were studied at baseline and during acute (intravenous infusion; Y: n = 13, O: n = 12) and chronic (500 mg/day for 30 days; Y: n = 10, O: n = 10) administration of ascorbic acid (vitamin C). At baseline, peripheral (brachial artery) BP did not differ in the two groups, but carotid artery compliance was 43% lower (1.2 +/- 0.1 vs. 2.1 +/- 0.1 mm(2)/mmHg x 10(-1), P < 0.01) and central (carotid) BP (systolic: 116 +/- 5 vs. 101 +/- 3 mmHg, P < 0.05, and pulse pressure: 43 +/- 4 vs. 36 +/- 3 mmHg, P = 0.16), carotid augmentation index (AIx; 27.8 +/- 7.8 vs. -20.0 +/- 6.6%, P < 0.001), and aortic pulse wave velocity (PWV; 950 +/- 88 vs. 640 +/- 38 cm/s, P < 0.01) were higher in the older men. Plasma ascorbic acid concentrations did not differ at baseline (Y: 71 +/- 5 vs. O: 61 +/- 7 micromol/l, P = 0.23), increased (P < 0.001) to supraphysiological levels during infusion (Y: 1240 +/- 57 and O: 1,056 +/- 83 micromol/l), and were slightly elevated (P < 0.001 vs. baseline) with supplementation (Y: 96 +/- 5 micromol/l vs. O: 85 +/- 6). Neither ascorbic acid infusion nor supplementation affected peripheral BP, heart rate, carotid artery compliance, central BP, carotid AIx, or aortic PWV (all P > 0.26). These results indicate that the adverse changes in large elastic artery compliance and central BP with aging in healthy men are not 1). mediated by ascorbic acid-sensitive oxidative stress (infusion experiments) and 2). affected by short-term, moderate daily ascorbic acid (vitamin C) supplementation.