Methylene blue inhibits hippocampal nitric oxide synthase activity in vivo.
The aim of the present study was to investigate the effect of methylene blue, a guanylate cyclase inhibitor, on the hippocampal nitric oxide synthase activity in vivo. We used a microdialysis-based technique of measuring conversion of [3H]l-arginine to [3H]l-citrulline in freely moving rats. The administration of methylene blue (0.1 and 1 mM) via the microdialysis probe caused a dose-dependent decrease in [3H]l-citrulline efflux comparable with the effect of unselective NOS inhibitor NG-nitro-L-arginine (2 mM). We conclude that methylene blue inhibits brain NOS activity in vivo and thus interferes with NO-cGMP cascade in different levels.
Volke
V
V
Department of Physiology, University of Tartu, Näituse 2, 50409, Tartu, Estonia. vallov@ut.ee
Wegener
G
G
Vasar
E
E
Rosenberg
R
R
D000818:Animals; D001120:Arginine / Q000493:pharmacokinetics; D001692:Biological Transport / Q000187:drug effects; D002956:Citrulline / Q000493:pharmacokinetics; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006624:Hippocampus / Q000187:drug effects / Q000201:enzymology*; D008297:Male; D008751:Methylene Blue / Q000494:pharmacology*; D017551:Microdialysis; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D014316:Tritium
D004791:Enzyme Inhibitors; D014316:Tritium; D002956:Citrulline; D001120:Arginine; D019001:Nitric Oxide Synthase; D008751:Methylene Blue