Effects of 5-cyclopropyl-2-[1-(2-fluoro-benzyl)-1H-pyrazolo[3,4-b]pyridine- 3-yl]pyrimidin-4-ylamine (BAY 41-2272) on smooth muscle tone, soluble guanylyl cyclase activity, and NADPH oxidase activity/expression in corpus cavernosum from wild-type, neuronal, and endothelial nitric-oxide synthase null mice

We aimed to characterize the relaxation induced by the soluble guanylyl cyclase (sGC) stimulator 5-cyclopropyl-2-[1-(2-fluoro-benzyl)-1H-pyrazolo[3,4-b] pyridine-3-yl]pyrimidin-4-ylamine (BAY 41-2272) and its pharmacological interactions with nitric oxide (NO) in the corpus cavernosum (CC) from wild-type (WT), endothelial nitric-oxide synthase (eNOS)^-/-, and neuronal (n)NOS^-/- mice. The effect of BAY 41-2272 on superoxide formation and NADPH oxidase expression was also investigated. Tissues were mounted in myographs for isometric force recording. Enzyme immunoassay kits were used for cGMP determination. sGC activity was determined in the supernatant fractions of the cavernosal samples by the conversion of GTP to cGMP. Superoxide formation and expression of NADPH oxidase subunits were studied using the reduction of ferricytochrome c and Western blot analysis, respectively. BAY 41-2272 (0.01-10 μM) relaxed CC with pEC₅₀ values of 6.36 ± 0.07 (WT), 6.27 ± 0.06 (nNOS^-/-), and 5.88 ± 0.07 (eNOS^-/-). The relaxations were accompanied by increases in cGMP levels. N ^ω-Nitro-L-arginine methyl ester inhibited BAY 41-2272-evoked responses in CC from WT and nNOS^-/-, but not eNOS^-/-. 1H-[1,2,4]Oxadiazolo[4,3-a]quinoxalin-1-one reduced and sildenafil potentiated the relaxations induced by BAY 41-2272 in all groups. BAY 41-2272 enhanced NO (endogenous and exogenous)-induced relaxations in a concentration-dependent manner. Expression and activity of sGC was similar among the different groups. Superoxide formation was reduced by BAY 41-2272 (0.1-1 μM). The compound also inhibited p22^phox and gp91^phox expression induced by 9,11-dideoxy-11α,9α-epoxymethanoprostaglandin F_2α (U46619). Our results demonstrated that sGC activation in the penis by BAY 41-2272 directly or via enhancement of NO effects may provide a novel treatment for erectile dysfunction, particularly in the event of an increased intrapenile oxidative stress.