Sustained attenuation of the cerebrovascular response to a 10 min whisker stimulation following neuronal nitric oxide synthase inhibition.
We examined the effect of type I nitric oxide synthase (neuronal isoform of NOS, nNOS) inhibition on the temporal profile of the cortical blood flow (CoBF) changes induced by a relatively long period (10 min) of whisker stimulation. To address this issue, we used laser-Doppler flowmetry (LDF) to continuously monitor the CoBF in rats anesthetized with alpha-chloralose, in a control condition, and 30 and 60 min following 7-nitroindazole (25 mg/kg, i.p.). Mechanical stimulation of all whiskers for 10 min led to a continuous and sustained CoBF increase with a mean integral response of 4030+/-764%. After 30 and 60 min nNOS inhibition the CoBF response was significantly reduced by 52 and 68%, respectively (P<0. 05) with no evidence of any compensatory mechanism during the whole stimulation period. These data show that regulation of the cerebral blood flow in response to an increased neuronal activity is a dynamic and tonic process in which nNOS plays an essential role.
Bonvento
G
G
Laboratoire de Recherches Cérébrovasculaires, CNRS UPR 646, IFR 6, 10, Avenue de Verdun, 75010, Paris, France. bonvento@ext.jussieu.fr
Cholet
N
N
Seylaz
J
J
D000818:Animals; D002560:Cerebrovascular Circulation / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D007191:Indazoles / Q000494:pharmacology*; D017078:Laser-Doppler Flowmetry; D009474:Neurons / Q000201:enzymology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors*; D052248:Nitric Oxide Synthase Type I; D010812:Physical Stimulation; D051381:Rats; D013997:Time Factors; D014738:Vibrissae / Q000502:physiology*
D004791:Enzyme Inhibitors; D007191:Indazoles; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; C496322:Nos1 protein, rat; C080122:7-nitroindazole