Molecular Mechanisms Underlying Rat Mesenteric Artery Vasorelaxation Induced by the Nitric Oxide-Independent Soluble Guanylyl Cyclase Stimulators BAY 41-2272 [5-Cyclopropyl-2-[1-(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridin-3-yl]pyrimidin-4-ylamine] and YC-1 [3-(5′-Hydroxymethyl-2′-furyl)-1-benzyl Indazole]

Abstract

The aim of this study was to investigate the mechanisms of relaxation to the nitric oxide (NO)-independent soluble guanylyl cyclase (sGC) stimulators 5-cyclopropyl-2-[1-(2-fluorobenzyl)-1H-pyrazolo [3,4-b]pyridin-3-yl]pyrimidin-4-ylamine (BAY 41-2272) and 3-(5Ј-hydroxymethyl-2Ј-furyl)-1-benzyl indazole (YC-1) in the rat mesenteric artery. In endothelium-intact rings, BAY 41-2272 (0.0001-1 M) and YC-1 (0.001-30 M) caused concentration-dependent relaxations (pEC 50 values of 8.21 Ϯ 0.05 and 6.75 Ϯ 0.06, respectively), which were shifted to the right by 6-fold in denuded rings. The sGC inhibitor H- [1,2,4]oxadiazolo [4,3,-a]quinoxalin-1-one (ODQ) (10 M) partially attenuated the maximal responses to BAY 41-2272 and YC-1 and displaced their curves to the right by 9-to 10-fold in intact and 3-fold in denuded vessels. The NO synthesis inhibitor N -nitro-L-arginine methyl ester (100 M) and the NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (100 M) reduced BAY 41-2272 and YC-1 relaxations, whereas the phosphodiesterase type 5 inhibitor sildenafil (0.1 M) potentiated these responses. The phosphatase inhibitor calyculin A (50 nM) reduced the relaxant responses, and high concentrations of BAY 41-2272 (1 M) and YC-1 (10 M) inhibited Ca 2ϩ -induced contractions in K ϩ -depolarized rings. BAY 41-2272 (0.1 M) and YC-1 (1 M) markedly elevated cGMP levels in an ODQsensitive manner. Coincubation of BAY 41-2272 or YC-1 with a NO donor resulted in a synergistic inhibition of phenylephrineinduced contractions paralleled by marked increases in cGMP levels. In conclusion, BAY 41-2272 and YC-1 relax the mesenteric artery through cGMP-dependent and -independent mechanisms, including blockade of Ca 2ϩ influx. The synergistic responses probably reflect the direct effects of NO and NOindependent sGC stimulators on the enzyme, thus representing a potential therapeutic effect by permitting reductions of nitrovasodilator dose.Endothelium-derived nitric oxide (NO) is considered a major regulator of vascular functions because of its pivotal importance in the control of blood vessel tone (Moncada et al., 1991). In vascular smooth muscle cells, NO-induced vasodilation is mediated through the stimulation of soluble guanylyl cyclase (sGC), resulting in the conversion of GTP to cGMP, which modulates the activity of several cGMP effector pro- ]benzodiazocine-10-carboxylic acid methyl ester; L-NAME, N -nitro-L-arginine methyl ester; Rp-8-pCPT-cGMPS, guanosine 3Ј,5Ј-cyclic monophosphorothioate, 8-(4-chlorophenylthio)-Rp-isomer; PDE5, phosphodiesterase type 5; PDE4, phosphodiesterase type 4; PKG, cGMP-dependent protein kinase; BK Ca , large conductance calcium-activated potassium channel; eNOS, endothelial nitric-oxide synthase.

Beneficial Effect of the Soluble Guanylyl Cyclase Stimulator BAY 41-2272 on Impaired Penile Erection in db/db−/− Type II Diabetic and Obese Mice

“…Considering that decreased NO availability is a common factor in diabetes-related ED, prolonged cavernosal relaxation in an in vivo situation would be extremely beneficial, leading to or improving the quality of an erection. In addition, this result supports the concept that BAY 41-2272 interacts with endogenous NO (Teixeira et al, 2006c(Teixeira et al, , 2007.…”

“…4C). This conclusion is reinforced by results obtained in rat mesenteric artery (Teixeira et al, 2006c), basilar artery (Teixeira et al, 2006b), and anococcygeus muscle (Teixeira et al, 2006a). A similar result was observed when tissue was coincubated with BAY 41-2272 for EFS but not ACh.…”

Phosphodiesterases Regulate BAY 41-2272-Induced VASP Phosphorylation in Vascular Smooth Muscle Cells

“…Based on the recent findings for BAY in terms of its mechanism of action and dependence on sGC and cGMP (Stasch et al, 2001; Bawankule et al, 2005; Teixeira et al, 2006), we sought to determine if BAY-induced increases in cGMP are via direct stimulation of sGC. Primary VSMCs were incubated with two chemically dissimilar inhibitors of sGC: NS 2028 (NS, 1 μM) or ODQ (10 μM), prior to stimulation with BAY (10 μM; Garthwaite et al, 1995; Morbidelli et al, 2010).…”

“…One other possible explanation is that BAY activates some other unidentified kinase in this cell that can phosphorylate VASP. BAY has also been shown to have effects apart from NO such as inhibition of Ca 2+ influx, stimulation of the sodium pump, or inhibition of PDE5 (Mullershausen et al, 2004; Bawankule et al, 2005; Teixeira et al, 2006). The latter is one possible explanation for this finding because an inhibition of PDE5 would increase cGMP and thus lead to phosphorylation of VASP.…”

Functional role of the soluble guanylyl cyclase α1 subunit in vascular smooth muscle relaxation☆

“…Also the observation that ODQ failed to inhibit the relaxant effect of 10 μmol/L BAY 41-2272 in the sGCα 1 +/+ aortic ring, suggests the involvement of (a) cGMPindependent mechanism(s) rather than sGCα 2 activation. There are reports on cGMP-independent mechanisms underlying BAY 41-2272 and YC-1 induced vasorelaxation, including inhibition of Ca 2+ entry [31] and activation of K + channels [32] and Na + -K + -ATPase [33].…”