L-NNA-sensitive regional cerebral blood flow augmentation during hypercapnia in type III NOS mutant mice.
The effect of NG-nitro-L-arginine (L-NNA) on regional cerebral blood flow (rCBF) response to hypercapnia (5% CO2 inhalation) was studied in urethan-anesthetized wild-type (SV-129) and type III nitric oxide (NO) synthase (NOS)-deficient mice, using laser-Doppler flowmetry and the closed cranial window technique. Resting rCBF during normocapnia decreased by approximately 25% after L-NNA superfusion in wild-type mice only (n = 18), suggesting a role for type III NOS in baseline blood flow. Hypercapnia augmented rCBF approximately 50% in both wild-type and type III NOS mutant mice. L-NNA superfusion (1 mM) inhibited this increase by approximately 60% in both strains. Hence, synthesis of NO by the constitutively expressed type I NOS contributes to blood flow augmentation during hypercapnia.
Department of Neurosurgery and Neurology, Massachusetts General Hospital, Charlestown, USA.
J
J
Ma
W
W
Meng
C
C
Ayata
P L
PL
Huang
M C
MC
Fishman
M A
MA
Moskowitz
D000287:Administration, Topical; D000818:Animals; D002560:Cerebrovascular Circulation / Q000187:drug effects*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006935:Hypercapnia / Q000235:genetics* / Q000503:physiopathology*; D051379:Mice; D018345:Mice, Knockout / Q000235:genetics*; D019001:Nitric Oxide Synthase / Q000235:genetics*; D019335:Nitroarginine / Q000494:pharmacology*; D014655:Vascular Resistance / Q000187:drug effects
D004791:Enzyme Inhibitors; D019335:Nitroarginine; D019001:Nitric Oxide Synthase