The nNOS/cGMP signal transducing system is involved in the cardiovascular responses induced by activation of NMDA receptors in the rostral ventrolateral medulla of cats.
Nitric oxide (NO) is synthesized from L-arginine by NO synthase (NOS). NO stimulates the soluble form of guanylyl cyclase (sGC) and induces accumulation of cyclic guanosine monophosphate (cGMP). The purpose of this study was to examine whether the cardiovascular responses induced by N-methyl-D-aspartate (NMDA) in the rostral ventrolateral medulla (RVLM) depend on the actions of NOS and sGC. In anesthetized cats, the extracellular NO level was measured by in vivo voltammetry using a nafion/porphyrine/o-phenylenediamine-coated carbon-fiber electrode. Microinjection of NMDA into the RVLM produced hypertension and bradycardia associated with NO formation. These NMDA-induced responses were attenuated by prior injections of 7-nitroindazole, a neuronal NO synthase (nNOS) inhibitor, and 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, a sGC inhibitor. These findings suggest that NO is involved in the NMDA-induced cardiovascular responses in the RVLM.
Wu
W C
WC
Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan.
Wang
Y
Y
Su
C K
CK
Chai
C Y
CY
D000818:Animals; D001794:Blood Pressure / Q000502:physiology; D001919:Bradycardia / Q000139:chemically induced / Q000503:physiopathology; D002415:Cats; D006152:Cyclic GMP / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D005260:Female; D006162:Guanylate Cyclase / Q000037:antagonists & inhibitors / Q000378:metabolism; D006339:Heart Rate / Q000502:physiology; D006973:Hypertension / Q000139:chemically induced / Q000503:physiopathology; D007191:Indazoles / Q000494:pharmacology; D008297:Male; D008526:Medulla Oblongata / Q000502:physiology*; D016202:N-Methylaspartate; D009569:Nitric Oxide / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D052248:Nitric Oxide Synthase Type I; D010069:Oxadiazoles / Q000494:pharmacology; D011810:Quinoxalines / Q000494:pharmacology; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*
C095284:1H-(1,2,4)oxadiazolo(4,3-a)quinoxalin-1-one; D004791:Enzyme Inhibitors; D018690:Excitatory Amino Acid Agonists; D007191:Indazoles; D010069:Oxadiazoles; D011810:Quinoxalines; D016194:Receptors, N-Methyl-D-Aspartate; D009569:Nitric Oxide; D016202:N-Methylaspartate; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; D006162:Guanylate Cyclase; D006152:Cyclic GMP; C080122:7-nitroindazole