“ Papaverine (3 microM) added to the organ bath 15 min before the contractile agent increased the relaxing … significantly decreased their IC50 (genistein 20.2 +/- 2.0 vs. 9.8 +/- 1.4 microM; kaempferol 10.1 +/- 1.6 vs. 6.6 +/- 0.… +/- 1.2 vs. 7.8 +/- 1.4 microM).”