Role of nitric oxide in hypoxic hypometabolism in rats.
Because it has been recently suggested that nitric oxide (NO) may mediate the effects of hypoxia on body temperature and ventilation, the present study was designed to assess more completely the effects of a neuronal NO synthase inhibitor (7-nitroindazole, 25 mg/kg ip), at ambient temperature of 26 and 15 degrees C, on the ventilatory (V), metabolic (O(2) consumption), and thermal changes (colonic and tail temperatures) induced by ambient hypoxia (fractional inspired O(2) of 11%) or CO hypoxia (fractional inspired CO of 0.07%) in intact, unanesthetized adult rats. At both ambient temperatures, 7-nitroindazole decreased oxygen consumption, colonic temperature, and V in normoxia. The drug reduced ambient or CO hypoxia-induced hypometabolism and ventilatory response, but the hypothermia persisted. It is concluded that NO arising from neural NO synthase plays an important role in the control of metabolism and V in normoxia. As well, it mediates, in part, the hypometabolic and the ventilatory response to hypoxia. The results are consistent with the notion that central nervous system hypoxia resets the thermoregulatory set point by decreasing brain NO.
Atelier de Physiologie Respiratoire, Faculté de Médecine Saint-Antoine, 75012 Paris, France.
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D000818:Animals; D001833:Body Temperature Regulation / Q000187:drug effects / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D000860:Hypoxia / Q000378:metabolism* / Q000503:physiopathology; D007191:Indazoles / Q000494:pharmacology; D008297:Male; D009569:Nitric Oxide / Q000378:metabolism* / Q000502:physiology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000502:physiology; D052248:Nitric Oxide Synthase Type I; D051381:Rats; D017208:Rats, Wistar; D012119:Respiration / Q000187:drug effects
D004791:Enzyme Inhibitors; D007191:Indazoles; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; C496322:Nos1 protein, rat; C080122:7-nitroindazole