Overexpression of inducible nitric oxide synthase in rostral ventrolateral medulla causes hypertension and sympathoexcitation via an increase in oxidative stress.
The present study examined the role of inducible nitric oxide synthase (iNOS) in the rostral ventrolateral medulla (RVLM) of the brain stem, where the vasomotor center is located, in the control of blood pressure and sympathetic nerve activity. Adenovirus vectors encoding iNOS (AdiNOS) or beta-galactosidase (Adbetagal) were transfected into the RVLM in Wistar-Kyoto (WKY) rats. Blood pressure and heart rate were monitored using a radiotelemetry system. iNOS expression in the RVLM was confirmed by immunohistochemical staining or Western blot analysis. Mean arterial pressure significantly increased from day 6 to day 11 after AdiNOS transfection, but did not change after Adbetagal transfection. Urinary norepinephrine excretion was significantly higher in AdiNOS-transfected rats than in Adbetagal-transfected rats. Microinjection of aminoguanidine or S-methylisothiourea, iNOS inhibitors, or tempol, an antioxidant, significantly attenuated the pressor response evoked by iNOS gene transfer. The levels of thiobarbituric acid-reactive substances, a marker of oxidative stress, were significantly greater in AdiNOS-transfected rats than in Adbetagal-transfected rats. Dihydroethidium fluorescence in the RVLM was increased in AdiNOS-transfected rats. In addition, nitrotyrosine-positive cells were observed in the RVLM only in AdiNOS-transfected rats. Intracisternal infusion of tempol significantly attenuated the pressor response and the increase in the levels of thiobarbituric acid-reactive substances induced by AdiNOS transfection. These results suggest that overexpression of iNOS in the RVLM increases blood pressure via activation of the sympathetic nervous system, which is mediated by an increase in oxidative stress.
Kimura
Yoshikuni
Y
Department of Cardiovascular Medicine, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan.
Hirooka
Yoshitaka
Y
Sagara
Yoji
Y
Ito
Koji
K
Kishi
Takuya
T
Shimokawa
Hiroaki
H
Takeshita
Akira
A
Sunagawa
Kenji
K
D000818:Animals; D000975:Antioxidants / Q000008:administration & dosage / Q000494:pharmacology; D001794:Blood Pressure; D001923:Brain Chemistry; D002417:Cattle; D003497:Cyclic N-Oxides / Q000008:administration & dosage / Q000494:pharmacology; D006339:Heart Rate; D006973:Hypertension / Q000201:enzymology / Q000209:etiology* / Q000235:genetics; D015918:Infusion Pumps, Implantable; D008297:Male; D008526:Medulla Oblongata / Q000201:enzymology* / Q000503:physiopathology; D051379:Mice; D017551:Microdialysis; D008845:Microinjections; D009569:Nitric Oxide / Q000096:biosynthesis; D019001:Nitric Oxide Synthase / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; D009638:Norepinephrine / Q000652:urine; D018384:Oxidative Stress; D011897:Random Allocation; D051381:Rats; D011921:Rats, Inbred WKY; D011993:Recombinant Fusion Proteins / Q000502:physiology; D013113:Spin Labels; D013481:Superoxides / Q000032:analysis; D013564:Sympathetic Nervous System / Q000503:physiopathology*; D014161:Transduction, Genetic; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000032:analysis; D014666:Vasomotor System / Q000502:physiology
D000975:Antioxidants; D003497:Cyclic N-Oxides; D011993:Recombinant Fusion Proteins; D013113:Spin Labels; D013481:Superoxides; D009569:Nitric Oxide; C002744:3-nitrotyrosine; D014443:Tyrosine; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; C496317:Nos2 protein, mouse; C496318:Nos2 protein, rat; C496315:Nos3 protein, mouse; C496316:Nos3 protein, rat; C001803:tempol; D009638:Norepinephrine