Hypoxic excitation of medullary vasomotor neurons in rats are not mediated by glutamate or nitric oxide.
Ischemic-hypoxic neuro-excitation and toxicity have been attributed to a rapid release of glutamate and formation of nitric oxide. We have now demonstrated that sympatho-excitatory response (1.2-fold increase in sympathetic nerve activity) induced by intratracheal administration of 100% N2 for 20 s in anesthetized rats and membrane inward currents (0.4-0.5 nA) induced by cyanide (300 microM) and hypoxia (saturated with 75% N2) of these neurons recorded in slices of rat rostral ventrolateral medulla were neither reduced by blocking glutamate receptors with kynurenate, synaptic transmission with tetrodotoxin nor by inhibiting nitric oxide synthase with N-nitro-L-arginine, indicating that glutamate, synaptic inputs, and nitric oxide are not involved in rapid responses of reticulospinal vasomotor neurons to hypoxia.
Sun
M K
MK
Department of Neurology and Neuroscience, Cornell University Medical College, New York, NY 10021.
Reis
D J
DJ
D015763:2-Amino-5-phosphonovalerate / Q000494:pharmacology; D000594:Amino Acid Oxidoreductases / Q000037:antagonists & inhibitors; D000818:Animals; D005971:Glutamates / Q000502:physiology*; D018698:Glutamic Acid; D002534:Hypoxia, Brain / Q000503:physiopathology*; D007278:Injections, Spinal; D007737:Kynurenine / Q000494:pharmacology; D008297:Male; D008526:Medulla Oblongata / Q000187:drug effects*; D009419:Nerve Tissue Proteins / Q000037:antagonists & inhibitors; D009569:Nitric Oxide / Q000502:physiology*; D019001:Nitric Oxide Synthase; D051381:Rats; D017207:Rats, Sprague-Dawley; D012966:Sodium Cyanide / Q000494:pharmacology; D013563:Sympathectomy, Chemical; D013779:Tetrodotoxin / Q000494:pharmacology; D014666:Vasomotor System / Q000187:drug effects*
D005971:Glutamates; D009419:Nerve Tissue Proteins; D009569:Nitric Oxide; D007737:Kynurenine; D018698:Glutamic Acid; D013779:Tetrodotoxin; D015763:2-Amino-5-phosphonovalerate; D019001:Nitric Oxide Synthase; D000594:Amino Acid Oxidoreductases; D012966:Sodium Cyanide