TY - JOUR AU - Li Yuan-jian AU - Duckles Sue Piper PY - 2016 TI - Mechanisms of relaxation by pyrogallol and methylthioninium chloride in perfused rat mesenteric artery JF - Acta Pharmacologica Sinica; Vol 15, No 2 (March 1994): Acta Pharmacologica Sinica Y2 - 2016 KW - N2 - In perfused rat mesenteric arteries without endothelium, pyrogallol (Pyr) or methylthioninium chloride (methylene blue, Met) produced a concentration-dependent relaxation. Superoxide dismutase abolished inhibition by Pyr, but not Met, of vasoconstrictor responses to transmural nerve stimulation (TNS). Neither catalase nor deferoxamine had any effect on vasodilator responses to Pyr or Met. Vasodilator responses to Pyr were unaltered by N omega-nitro-L-arginine methyl ester (L-NAME), indomethacin, or capsaicin. Similarly, the relaxing effect of Met was unaffected by indomethacin or capsaicin. These findings suggest that vasodilator responses to Pyr may be due to endothelial-independent generation of superoxide anion. In contrast the relaxation produced by Met appears to be due to a direct action on vascular smooth muscle independent of superoxide anion generation UR - http://www.chinaphar.com/article/view/6184