title: Cardiac autonomic function in acutely nitric oxide deficient hypertensive rats: role of the sympathetic nervous system and oxidative stress.
abstract: We evaluated the role of the sympathetic nervous system and oxidative stress in hemodynamic and autonomic control after acute inhibition of the synthesis of nitric oxide, using intravenous (i.v.) injection of 30 mg·kg(-1) N(G)-nitro-l-arginine methyl ester (L-NAME) in adult Wistar rats. Baroreflex sensitivity (BRS) and heart rate variability (HRV) were measured as indices of cardiac autonomic control, before and after L-NAME treatment in rats with intact autonomic innervation, and in rats with chemical sympathectomy by 6-hydroxydopamine. Serum malondialdehyde (MDA) was measured as a marker of oxidative stress. In control rats, L-NAME treatment resulted in a significant rise in blood pressure, augmentation of BRS, and enhanced serum MDA. HRV showed an attenuation of total spectral power and high frequency spectral power, along with a rise of the low to high frequency ratio (LF:HF). Administration of L-NAME produced a pressor response even in sympathectomised rats, but augmented BRS was not observed, and the high frequency spectral power showed an increase, in addition to a significant decline of LF:HF and serum MDA. We therefore conclude that even though pressor response was unaffected, reversal of cardiac autonomic responses and decline in oxidative stress following sympathectomy in L-NAME-treated rats reflects a significant role for sympathetic innervation in acute L-NAME-induced hypertension.
authors: a Department of Physiology, Vardhaman Mahavir Medical College & Safdarjung Hospital, New Delhi, India.
authors: Meenakshi
authors: M
authors: Chaswal
authors: Shobha
authors: S
authors: Das
authors: Jagdish
authors: J
authors: Prasad
authors: Anju
authors: A
authors: Katyal
authors: Mohammad
authors: M
authors: Fahim
mesh_terms: D000818:Animals; D017704:Baroreflex; D006321:Heart / Q000294:innervation / Q000503:physiopathology*; D006339:Heart Rate / Q000187:drug effects; D006973:Hypertension / Q000378:metabolism / Q000503:physiopathology*; D008297:Male; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000037:antagonists & inhibitors / Q000378:metabolism*; D018384:Oxidative Stress / Q000187:drug effects*; D016627:Oxidopamine; D017208:Rats, Wistar; D013563:Sympathectomy, Chemical; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000503:physiopathology*; D013565:Sympatholytics
chemical_list: D013565:Sympatholytics; D009569:Nitric Oxide; D016627:Oxidopamine; D019331:NG-Nitroarginine Methyl Ester