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Oxidative Medicine and Cellular Longevity
Volume 2013, Article ID 517045, 9 pages
http://dx.doi.org/10.1155/2013/517045
Research Article

The Effect of Alpha-Lipoic Acid on Mitochondrial Superoxide and Glucocorticoid-Induced Hypertension

1Department of Renal Medicine, St George Hospital, Kogarah, NSW 2217, Australia
2Department of Medicine, University of New South Wales, Sydney, NSW 2052, Australia
3John Curtin School of Medical Research, Australian National University, Canberra, ACT 0200, Australia
4Cardiovascular Research Unit, The Canberra Hospital, Canberra, ACT 2605, Australia

Received 11 July 2012; Accepted 4 January 2013

Academic Editor: Jose Magalhaes

Copyright © 2013 Sharon L. H. Ong et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Aims. To examine the effect of alpha-lipoic acid, an antioxidant with mitochondrial superoxide inhibitory properties, on adrenocorticotrophic hormone- (ACTH-HT) and dexamethasone-induced hypertensions (DEX-HT) in rats and if any antihypertensive effect is mediated via mitochondrial superoxide inhibition. Methods. In a prevention study, rats received ground food or alpha-lipoic-acid-laced food (10 mg/rat/day) for 15 nights. Saline, adrenocorticotrophic hormone (ACTH, 0.2 mg/kg/day), or dexamethasone (DEX, 10 μg/rat/day) was injected subcutaneously from day 5 to day 11. In a reversal study, rats received alpha-lipoic-acid-laced food 4 days after commencement of saline or DEX. Tail-cuff systolic blood pressure (SBP) was measured second daily. Kidney mitochondrial superoxide was examined using (MitoSOX) Red (MitoSOX) via flow cytometry. Results. SBP was increased by ACTH ( ) and DEX ( ). Alpha-lipoic acid alone did not alter SBP. With alpha-lipoic acid pretreatment, SBP was increased by ACTH ( ) but not by DEX. Alpha-lipoic partially prevented ACTH-HT ( ) and fully prevented DEX-HT ( ) but failed to reverse DEX-HT. ACTH and DEX did not increase MitoSOX signal. In ACTH-hypertensive rats, high-dose alpha-lipoic acid (100 mg/rat/day) did not decrease SBP further but raised MitoSOX signal ( ), suggesting prooxidant activity. Conclusion. Glucocorticoid-induced hypertension in rats is prevented by alpha-lipoic acid via mechanisms other than mitochondrial superoxide reduction.