The nNos/cGMP mediation of the depressor response to NMDA receptor stimulation in the caudal ventrolateral medulla.
Using in vivo voltammetry to directly measure extracellular nitric oxide (NO) levels, our previous studies suggested that the neuronal NO synthase (nNOS) and cyclic guanosine monophosphate (cGMP) signal transducing systems are involved in the cardiovascular responses elicited by activation of N-methyl-D-aspartate (NMDA) receptors in the rostral ventrolateral medulla. In this study, we examined if the depressor responses elicited by activation of NMDA receptors in the caudal ventrolateral medulla (CVLM) also depend on the actions of nNOS and soluble guanylyl cyclase. In anesthetized cats, microinjection of NMDA into the CVLM produced hypotension and bradycardia associated with NO formation. These NMDA-induced responses were attenuated by prior injections of 2-amino-5-phosphonopentanoate (a NMDA receptor competitive antagonist), 7-nitroindazole (a nNOS inhibitor) and 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (an inhibitor of soluble guanylyl cyclase). These findings suggest that NO is also involved in the NMDA-induced depressor responses of the CVLM.
Wu
Wun-Chin
WC
Department of Electronic Engineering, National Penghu Institute of Technology, Penghu, Taiwan, ROC.
Su
Chun-Kuei
CK
Yang
Ching-Yue
CY
Chai
Chok-Yung
CY
D000758:Anesthesia; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D002415:Cats; D006152:Cyclic GMP / Q000378:metabolism*; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D005260:Female; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D008297:Male; D008526:Medulla Oblongata / Q000187:drug effects / Q000378:metabolism*; D016202:N-Methylaspartate / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D052248:Nitric Oxide Synthase Type I; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism*
D018690:Excitatory Amino Acid Agonists; D016194:Receptors, N-Methyl-D-Aspartate; D009569:Nitric Oxide; D016202:N-Methylaspartate; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; D006152:Cyclic GMP