title: Effects of hypoxia and reoxygenation on nitric oxide production and cerebral blood flow in developing rat striatum.
abstract: We investigated the role of nitric oxide (NO) in the regulation of regional cerebral blood flow (rCBF) during hypoxia and reoxygenation in developing rat striatum. The subjects were urethane-anesthetized 7- and 14-d-old rats. After 120 min of baseline measurements, the rats received an i.p. injection of either saline (as a control) or an NO synthase inhibitor, N-nitro-L-arginine methyl ester (L-NAME, 30 mg/kg) 30 min before hypoxia. Then they were subjected to a 60-min hypoxia in 8% O2, followed by a 60-min recovery in 21% O2. rCBF and NO concentration in the striatum were measured by laser Doppler flowmetry and an NO electrode throughout the experimental period. In the controls, rCBF decreased to 93 +/- 3% of baseline during hypoxia and increased to 124 +/- 3% of baseline during reoxygenation in 7-d-old rats (n = 13), whereas rCBF increased during both hypoxia and reoxygenation in 14-d-old rats to 125 +/- 6% and 168 +/- 6% of baseline, respectively (n = 17). L-NAME attenuated the hyperemic response to hypoxia/reoxygenation in both ages (n = 11, in each age). Striatal NO production increased during hypoxia and reoxygenation in both ages, but the increase was significantly less in 7-d-old than in 14-d-old rats. The NO increase was associated with the increase in rCBF, and both were attenuated by L-NAME. We speculate that NO release during hypoxia/reoxygenation modulates rCBF. The immature young rat brain may have less capacity to activate NO production than the more developed brain.
authors.affiliation: Department of Pediatrics, Kobe University School of Medicine, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Ioroi
authors.forename: M
authors.initials: M
authors.lastname: Yonetani
authors.forename: H
authors.initials: H
authors.lastname: Nakamura
mesh_terms: D000375:Aging / Q000502:physiology*; D000818:Animals; D002560:Cerebrovascular Circulation / Q000187:drug effects; D003342:Corpus Striatum / Q000098:blood supply / Q000187:drug effects / Q000502:physiology*; D000860:Hypoxia / Q000503:physiopathology*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology*; D009569:Nitric Oxide / Q000096:biosynthesis*; D010100:Oxygen / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012039:Regional Blood Flow
chemical_list: D009569:Nitric Oxide; D010100:Oxygen; D019331:NG-Nitroarginine Methyl Ester