Oxidative stress mediates angiotensin II-dependent stimulation of sympathetic nerve activity.
Evidence indicates that angiotensin II (Ang II) enhances sympathetic nervous system (SNS) activity centrally and peripherally, but the exact mechanisms of this activation are not well established. We have previously shown that infusion of Ang II in the lateral cerebral ventricle raises blood pressure (BP), renal sympathetic nervous system activity (RSNA), and norepinephrine (NE) secretion from the posterior hypothalamic nuclei (PH), and reduces the abundance of interleukin-1beta (IL-1beta) and neuronal NO synthase (nNOS) mRNA in the PH. Pretreatment with an Ang II type 1 (AT1) receptor antagonist abolished these effects of Ang II. The data support the hypothesis that Ang II stimulates SNS through activation of AT1 receptors and downregulation of nNOS. In the current studies, we tested the hypothesis that the effects of Ang II on central SNS are mediated by reactive oxygen species. To this end, we evaluated the effects of Ang II alone or in combination with 2 superoxide dismutase (SOD) mimetics, tempol (4-hydroxy-2,2,6,6-tetramethyl piperidinoxyl) and polyethylene glycol-SOD (PEG-SOD) on BP, NE secretion from the PH, RSNA, and abundance of IL-1beta and nNOS mRNA in the PH Ang II raised BP, NE secretion from the PH, and RSNA and reduced the abundance of IL-1beta and nNOS mRNA in the PH. Tempol and PEG-SOD completely abolished these actions of Ang II. In conclusion, these studies support the hypothesis that the effects of centrally administered Ang II on the SNS are mediated by increased oxidative stress in brain regions involved in the noradrenergic control of BP.
Campese
Vito M
VM
Division of Nephrology, Hypertension Center, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA. campese@usc.edu
Shaohua
Ye
Y
Huiquin
Zhong
Z
D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects; D001921:Brain / Q000378:metabolism*; D003497:Cyclic N-Oxides / Q000494:pharmacology; D004338:Drug Combinations; D016166:Free Radical Scavengers / Q000494:pharmacology; D007034:Hypothalamus, Posterior / Q000378:metabolism; D007375:Interleukin-1 / Q000378:metabolism; D007668:Kidney / Q000294:innervation; D008125:Locus Coeruleus / Q000378:metabolism; D008297:Male; D052248:Nitric Oxide Synthase Type I / Q000378:metabolism; D009638:Norepinephrine / Q000378:metabolism; D018384:Oxidative Stress; D010286:Paraventricular Hypothalamic Nucleus / Q000378:metabolism; D011092:Polyethylene Glycols / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013113:Spin Labels; D013482:Superoxide Dismutase / Q000494:pharmacology; D013564:Sympathetic Nervous System / Q000187:drug effects* / Q000502:physiology*
D000975:Antioxidants; D003497:Cyclic N-Oxides; D004338:Drug Combinations; D016166:Free Radical Scavengers; D007375:Interleukin-1; D013113:Spin Labels; D000804:Angiotensin II; D011092:Polyethylene Glycols; D052248:Nitric Oxide Synthase Type I; D013482:Superoxide Dismutase; C063471:polyethylene glycol-superoxide dismutase; C001803:tempol; D009638:Norepinephrine