Superoxide scavenging effects of N-acetylcysteine and vitamin C in subjects with essential hypertension

Schneider, M.P., Delles, C. , Schmidt, B.M.W., Oehmer, S., Schwarz, T.K., Schmieder, R.E. and John, S. (2005) Superoxide scavenging effects of N-acetylcysteine and vitamin C in subjects with essential hypertension. American Journal of Hypertension, 18(8), pp. 1111-1117. (doi: 10.1016/j.amjhyper.2005.02.006)

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<p><b>Background:</b> It is not known whether the beneficial effects of N-acetylcysteine (NAC) in conditions associated with increased oxidative stress are caused by direct superoxide scavenging. We therefore compared the acute superoxide scavenging efficacy of NAC against vitamin C (VITC) on impaired endothelium-dependent vasodilation in subjects with essential hypertension.</p> <p><b>Methods:</b> In a cross-over randomized study, the effects of intra-arterial administration of either NAC (48 mg/min) or VITC (18 mg/min) were examined in 15 subjects with essential hypertension and in 15 normotensive control subjects. Both endothelium-dependent and endothelium-independent vasodilation were determined as forearm blood flow (FBF) response to the intra-arterial administration of acetylcholine (Ach) and sodium nitroprusside (NP) in doses of 12 and 48 g/min and 3.2 and 12.8 g/min, respectively.</p> <p><b>Results:</b> Subjects with essential hypertension had impaired responses to both doses of Ach (% FBF to higher dose of Ach: 325 146 in subjects with essential hypertension v 540 199 in control subjects; P = .02) and an impaired response to the higher dose of NP (330 108 v 500 199; P = .03). The intra-arterial administration of NAC had no effect on these responses (higher dose of Ach: 325 146 without v 338 112 with NAC, NS). In contrast, intra-arterial VITC improved both the response to Ach (320 132 without v 400 185 with VITC, P = .05) and to NP (383 162 v 447 170, P = .05).</p> <p><b>Conclusions:</b> We found that NAC showed no statistically significant effect on either endothelium-dependent or endothelium-independent vasodilation in hypertensive subjects, whereas VITC did. We conclude that NAC is therefore not an effective superoxide scavenger in vivo. Other, nonimmediate effects such as the generation of glutathione may explain the beneficial effects of NAC in conditions associated with oxidative stress.</p>

Item Type:Articles
Glasgow Author(s) Enlighten ID:Schneider, Dr Markus and Delles, Professor Christian
Authors: Schneider, M.P., Delles, C., Schmidt, B.M.W., Oehmer, S., Schwarz, T.K., Schmieder, R.E., and John, S.
College/School:College of Medical Veterinary and Life Sciences > Institute of Cardiovascular and Medical Sciences
Journal Name:American Journal of Hypertension
ISSN (Online):1941-7225

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