Central administration of Angiotensin II raises blood pressure and sympathetic nerve activity, effects that are completely abolished by superoxide dismutase mimetics like tempol and PEG-SOD.
Does the administration of SOD mimetics (tempol or PEG-SOD) prevent Angiotensin II-induced increases in sympathetic nervous system activity and blood pressure in a preclinical model?
The central sympathoexcitatory and pressor effects of Angiotensin II are mediated by increased oxidative stress in the brain.
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 et al. (Tue,) reported a other. Angiotensin II with or without SOD mimetics (tempol and PEG-SOD) vs. Angiotensin II alone was evaluated on Blood pressure, norepinephrine secretion, renal sympathetic nervous system activity, and abundance of IL-1beta and nNOS mRNA. Central administration of Angiotensin II raises blood pressure and sympathetic nerve activity, effects that are completely abolished by superoxide dismutase mimetics like tempol and PEG-SOD.