title: Role of nitric oxide in thermoregulation and hypoxic ventilatory response in obese Zucker rats.
abstract: To examine the role of nitric oxide (NO) on thermoregulation and control of breathing in obesity, awake obese and age-matched lean Zucker (Z) rats underwent a sustained hypoxic challenge. Body temperature (Tb), oxygen consumption (V O(2)) and ventilation (V E) were measured during room air and during 30-min of hypoxia (10% O(2)) after intraperitoneal administration of either 100 mg/kg of N(G)-nitro-L-arginine methyl ester (L-NAME), a nonspecific NOS inhibitor, 25 mg/kg of 7-nitroindazole (7-NI), a selective neuronal NOS inhibitor, or equal volume of vehicle (dimethyl sulfoxide: DMSO) as control. Tb in obese rats during room air was significantly lower than that of lean rats. Hypoxia induced a more pronounced drop in Tb and V O(2) in lean rats than in obese rats. Tb in lean Z rats dropped significantly by approximately 0.2 degrees C after L-NAME and, more markedly, by approximately 1.1 degrees C after 7-NI compared with control during room air, whereas Tb in obese Z rats was unaffected. L-NAME and 7-NI attenuated hypoxia-induced hypothermia or hypometabolism in lean rats, but not in obese rats. Lean rats exhibited an abrupt increase in V E in response to hypoxia followed by a gradual decline in V E. In contrast, obese rats displayed an initial increase in V E that plateaued during sustained hypoxia. Both L-NAME and 7-NI induced marked decreases in V E during room air and hypoxia compared with control lean rats, whereas V E was virtually unaffected by either agent in obese rats. The present results suggest that the blunted thermoregulatory and ventilatory responses to hypoxia in obese Z rats may be attributed to reduced activity of NOS in the central nervous system.
authors.affiliation: Department of Physiology and Biophysics, University at Buffalo, The State University of New York, Buffalo, New York, USA.
authors.forename: H
authors.initials: H
authors.lastname: Nakano
authors.forename: S D
authors.initials: SD
authors.lastname: Lee
authors.forename: A D
authors.initials: AD
authors.lastname: Ray
authors.forename: J A
authors.initials: JA
authors.lastname: Krasney
authors.forename: G A
authors.initials: GA
authors.lastname: Farkas
mesh_terms: D000818:Animals; D001833:Body Temperature Regulation / Q000502:physiology*; D002490:Central Nervous System / Q000502:physiology; D000860:Hypoxia / Q000503:physiopathology; D008297:Male; D009569:Nitric Oxide / Q000494:pharmacology*; D009765:Obesity / Q000150:complications / Q000503:physiopathology*; D010101:Oxygen Consumption; D051381:Rats; D011924:Rats, Zucker; D012119:Respiration
chemical_list: D009569:Nitric Oxide