[Hyperoxic vasoconstriction in the brain is realized by inactivation of nitric oxide by superoxide anions].
We tested a hypothesis that the cerebral blood flow (CBF) is reduced at hyperbaric oxygen due to inactivation of nitric oxide (NO) by superoxide anions (O2). In our experiments, the CBF was measured under hyperbaric oxygenation (HBO) 4ATA after inhibition of NO synthesis and inactivation of O2. The CBF was reduced at HBO exposure. Inhibition of NO--synthase type I and III (NOS) by L-NAME in the air caused the same decreasing of the CBF as at 4 ATA HBO. Hyperbaric vasoconstriction was diminished after NOS inhibition. Intravenous injection of superoxide dismutase (CuZn SOD) increased the CBF in the air and HBO exposure. This effect disappeared at preliminary NOS inhibition. These data suggest that inactivation of NO by O2 is a more effective mechanism of HBO vasoconstriction.
I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Acad. Sci., 194223, St. Petersburg, pr. M. Toreza, 44, Russia.
S Iu
SIu
Zhiliaev
A N
AN
Moskvin
T F
TF
Platonova
D R
DR
Gutsaeva
I V
IV
Churilina
I T
IT
Demchenko
D000818:Animals; D002560:Cerebrovascular Circulation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006931:Hyperbaric Oxygenation; D008297:Male; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D010100:Oxygen / Q000494:pharmacology*; D051381:Rats; D013482:Superoxide Dismutase / Q000494:pharmacology; D013481:Superoxides / Q000378:metabolism*; D014661:Vasoconstriction
D004791:Enzyme Inhibitors; D013481:Superoxides; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D013482:Superoxide Dismutase; D010100:Oxygen; D019331:NG-Nitroarginine Methyl Ester