Influence of nitrovasodilators and cyclooxygenase inhibitors on cerebral vasoreactivity in conscious rabbits

Since the nitric oxide (NO) and cyclooxygenase pathways have been suggested to have important roles in most vasodilations, our aim was to study the in fluence of cyclooxygenase inhibitors and nitrovasodilators on cerebrovascul ar reserve capacity. Corticocerebral blood flow was measured by hydrogen po larography during hypercapnia and acetazolamide stimuli in conscious rabbit s. The measurements were repeated in the presence of N-omega-nitro-L-argini ne methyl ester (L-NAME) and indomethacin as nitric oxide synthase (NOS) an d cyclooxygenase inhibitors. The effects of nitroglycerin and isosorbide-5- nitrate were also tested. L-NAME completely, while indomethacin markedly in hibited the hypercapnic corticocerebral blood flow response. Nitroglycerin and isosorbide-5-nitrate significantly attenuated hypercapnia elicited cort icocerebral blood flow increase. The different treatments reduced only mode rately the acetazolamide-induced corticocerebral blood flow response. These results lend support to the hypothesis that antithrombotic and antiinflamm atory medication (cyclooxygenase inhibitors) and nitrovasodilator treatment s could interfere with the measurement of cerebrovascular reactivity result ing in underestimation of the cerebrovascular reserve capacity in patients taking these drugs. (C) 2001 Published by Elsevier Science B.V.