Soluble Guanylate Cyclase Stimulator BAY Research Articles

Soluble guanylate cyclase stimulator BAY 41-8543 and female sex ameliorate uremic aortic remodeling in a rat model of mild uremia.

Cardiovascular disease is the leading comorbidity in renal patients and has been related to impaired nitric oxide signaling. Estrogens exert protective effects on the vascular system. This study investigates the effects of biological sex and nitric oxide-independent soluble guanylate cyclase (sGC) stimulator BAY 41-8543 on aortic remodeling in experimental mild uremia. Age-matched male and female Wistar rats were assigned for 18 weeks into sham-operated, subtotally nephrectomized (SNX), SNX + BAY 41-8543 and SNX + hydralazine. Analysis involved functional, histological, and molecular kidney and thoracic aorta parameters. SNX significantly increased SBP, which was comparably reduced to control levels by BAY 41-8543 and hydralazine. In SNX males, uremic aortic remodeling was characterized by marked media thickening and increased media-to-lumen ratio (P < 0.01), vascular smooth muscle cell (VSMC) proliferation, macrophage infiltration, extracellular matrix turnover, decreased aortic elastin-to-collagen ratio (P < 0.01) and endothelial nitric oxide-synthase (eNOS) mRNA expression (P < 0.05). No significant alterations of aortic media-to-lumen ratio, VSMC proliferation, macrophage infiltration, matrix metalloproteinase-2, and eNOS mRNA expressions were seen in female uremic animals. BAY 41-8543 significantly ameliorated uremic aortic remodeling and stiffening involving reduced VSMC proliferation, collagen I-deposition, extracellular matrix turnover, and increased elastin content and eNOS mRNA expression. Hydralazine treatment did not substantially alter aortic remodeling. Experimental mild uremia leads to pronounced aortic hypertrophic remodeling and stiffening with sex-dependent alternations, and these are more severe in male rats. BAY 41-8543 ameliorates uremic aortic remodeling in a blood pressure-independent manner. The results suggest that sGC-stimulators may offer a novel treatment mode for pathological arterial wall remodeling in patients with impaired renal function.

The Effects of Cyclic Guanylate Cyclase Stimulation on Right Ventricular Hypertrophy and Failure Alone and in Combination With Phosphodiesterase-5 Inhibition

We investigated if soluble guanylate cyclase stimulation either alone or in combination with phosphodiesterase-5 (PDE5) inhibition could prevent pressure overload-induced right ventricular (RV) hypertrophy and failure. The soluble guanylate cyclase stimulator BAY 41-2272 (BAY, 10 mg · kg⁻¹ · d⁻¹) either alone or in combination (BAY + SIL) with a PDE5 inhibitor sildenafil (SIL, 100 mg · kg⁻¹ · d⁻¹) was examined for prevention of RV hypertrophy and failure in Wistar rats (n = 73) operated by pulmonary trunk banding. All treatments failed to inhibit the development of RV hypertrophy and failure. In the BAY and BAY + SIL groups, there was an increased mortality. Mean arterial blood pressure was lowered and cardiac output increased in the BAY + SIL group. Systolic RV pressure was increased in the BAY and BAY + SIL groups possibly because of an inotropic response and/or increased venous return. Stimulation of soluble guanylate cyclase by BAY 41-2272 alone or in combination with sildenafil failed to prevent the development of RV hypertrophy and failure in rats subjected to pulmonary trunk banding. An increased mortality was observed in animals treated by BAY 41-2272 alone and in combination with sildenafil.

Circulation : Clinical Summaries

<i>Circulation</i> : Clinical Summaries

A soluble guanylate cyclase stimulator, BAY 41-8543, preserves right ventricular function in experimental pulmonary embolism

Pulmonary embolism (PE) increases pulmonary vascular resistance, causing right ventricular (RV) dysfunction, and poor clinical outcome. Present studies test if the soluble guanylate cyclase stimulator BAY 41-8543 reduces pulmonary vascular resistance and protects RV function. Experimental PE was induced in anesthetized, male Sprague–Dawley rats by infusing 25 μm polystyrene microspheres (1.95 million/100 g body wt, right jugular vein) producing moderate PE. Pulmonary artery vascular resistance, estimated as RVPSP/CO, increased 3-fold after 5 h of PE. Treatment with BAY 41-8543 (50 μg/kg, I.V.; given at the time of PE induction) normalized this index by reducing RVPSP and markedly increasing CO, via preservation of heart rate and stroke volume. Ex vivo RV heart function showed minimal changes at 5 h of PE, but decreased significantly after 18 h of PE, including peak systolic pressure (PSP, Control 39 ± 1 mmHg vs. 19 ± 3 PE), +dP/dt (1192 ± 93 mmHg/s vs. 444 ± 64) and −dP/dt (−576 ± 60 mmHg/s vs. −278 ± 40). BAY 41-8543 significantly improved all three indices of RV heart function (PSP 35 ± 3.5, +dP/dt 1129 ± 100, −dP/dt −568 ± 87). Experimental PE produced increased PVR and RV dysfunction, which were ameliorated by treatment with BAY 41-8543. Thus, there is vasodilator reserve in this model of experimental PE that can be exploited to reduce the stress upon the heart and preserve RV contractile function.

Vas deferens smooth muscle responses to the nitric oxide-independent soluble guanylate cyclase stimulator BAY 41‐2272

The nitric oxide–cGMP signaling pathway modulates the ejaculatory functions. The nitric oxide (NO)-independent soluble guanylate cyclase haem-dependent stimulator BAY 41‐2272 potently relaxes different types of smooth muscles. However, no study investigated its effects in vas deferens smooth muscle. Therefore, we designed experiments to evaluate the in vitro relaxing responses of vas deferens to BAY 41‐2272. The effects of prolonged oral intake with BAY 41‐2272 in vas deferens contractions of rats treated chronically with the NO synthase inhibitor Nω-nitro-L-arginine methyl ester (L-NAME) were also investigated. BAY 41‐2272 (0.001–100μM) produced concentration-dependent relaxations in the prostatic and epididymal portions of vas deferens, an effect markedly reduced by the soluble guanylate cyclase inhibitor ODQ (100μM). BAY 41‐2272 significantly increased cGMP levels that were fully prevented by ODQ. In separate protocols, rats received L-NAME (20mg/rat/day) concomitantly with BAY 41‐2272 (10mg/kg/day, 4weeks), after which vas deferens contractions to electrical-field stimulation and noradrenaline were achieved. Electrical-field stimulation (1–32Hz) evoked frequency-dependent contractions that were significantly enhanced in L-NAME-treated rats. Co-treatment with BAY 41‐2272 fully reversed the increased contractile responses in L-NAME group. Noradrenaline (0.01–100μM)-induced contractions were also greater in L-NAME-treated rats, and that was normalized by BAY 41‐2272. In conclusion, BAY 41‐2272 potently relaxes in vitro rat vas deferens smooth muscle and elevates the cGMP levels in an ODQ-sensitive manner. Moreover, prolonged oral intake with BAY 41‐2272 restores the enhanced contractile vas deferens activity in rats treated with L-NAME. NO-independent soluble guanylate cyclase stimulators may be an alternative treatment for premature ejaculation.

Impact of Biological Gender and Soluble Guanylate Cyclase Stimulation on Renal Recovery After Relief of Unilateral Ureteral Obstruction

Gender difference and nitric oxide deficiency contribute to the progression of many chronic kidney diseases. In a model of unilateral ureteral obstruction relief we analyzed the impact of biological gender and nitric oxide/cyclic guanosine monophosphate signaling stimulation on renal disease severity and restoration. Female and male rats underwent sham surgery or unilateral ureteral obstruction. After 5-day unilateral ureteral obstruction female and male rats were assigned to obstruction relief alone or obstruction relief plus 7-day treatment with the soluble guanylate cyclase stimulator BAY 41-8543. Compared to male rats with obstruction relief renal disease was less severe in female rats, which had significantly less tubulointerstitial matrix accumulation and tubular atrophy. In each gender group α1 and β1-soluble guanylate cyclase was comparably and significantly increased but female rats produced significantly more cyclic guanosine monophosphate after treatment with the soluble guanylate cyclase stimulator. In each group BAY 41-8543 treatment was associated with significant amelioration of renal matrix protein expansion, macrophage infiltration, tubular apoptosis and atrophy. Female gender is protective for unilateral ureteral obstruction relief. This was linked to higher sensitivity of the soluble guanylate cyclase enzyme and cyclic guanosine monophosphate production in response to BAY 41-8543. In these female and male rats enhancing the signaling of nitric oxide/cyclic guanosine monophosphate with BAY 41-8543 significantly accelerated the restoration of renal architecture after obstruction relief and largely ameliorated the differences in disease severity due to the gender disparity.

Mechanism of relaxation and interaction with nitric oxide of the soluble guanylate cyclase stimulator BAY 41‐2272 in mouse gastric fundus and colon

BAY 41‐2272 is a heme-dependent nitric oxide-independent soluble guanylate cyclase (sGC) stimulator, but its relaxant effect in vascular, respiratory and urogenital tissue is only partially dependent on sGC activation. As its mechanism of action has not been studied in the gastrointestinal tract, it was investigated in mouse gastric fundus and colon. Circular smooth muscle strips were mounted in organ baths under non-adrenergic non-cholinergic (NANC) conditions for isometric force recording and cGMP levels were determined using an enzyme immunoassay kit. BAY 41‐2272 induced concentration-dependent relaxation in both tissues and increased cGMP levels. The sGC inhibitor ODQ totally inhibited this BAY 41-2272-induced increase of cGMP, but only partially reduced the corresponding relaxation. The PDE-5 inhibitor sildenafil had no effect on BAY 41-2272-induced responses. The NO synthase inhibitor L-NAME caused a significant decrease in BAY 41-2272-induced responses in colonic strips. Electrical field stimulation in the presence of BAY 41‐2272 induced increased NANC relaxation in fundus, while in colon, rebound contraction at the end of the stimulation train was no longer visible. This suggests synergy with endogenously released NO. Responses to BAY 41‐2272 were not significantly influenced by apamin, charybdotoxin or ouabain, excluding interaction with small, intermediate and large conductance Ca2+-activated K+ channels and with Na+–K+-ATPase. Under depletion of intracellular calcium, CaCl2-induced contractions were significantly reduced by BAY 41‐2272 in an ODQ-insensitive way. The present study demonstrates that BAY 41‐2272 exerts its relaxing effect in mouse gastric fundus and colon partially through a cGMP-dependent mechanism and at least one additional cGMP-independent mechanism involving Ca2+-entry blockade.

Stimulation of Soluble Guanylate Cyclase Improves Renal Recovery After Relief of Unilateral Ureteral Obstruction

The antifibrotic effects of soluble guanylate cyclase stimulation and cyclic guanosine monophosphate production have been observed in cases of anti-thy1-induced renal disease. We analyzed the action of the specific soluble guanylate cyclase stimulator BAY 41-8543 on the renal recovery phase in rats with unilateral ureteral obstruction after obstruction was relieved. Sprague-Dawley® rats underwent reversible unilateral ureteral obstruction for 5 days, after which obstruction was relieved. Rats were randomly assigned to unilateral ureteral obstruction and unilateral ureteral obstruction plus BAY 41-8543 (10 mg/kg body weight daily). Seven days after relief of obstruction we determined treatment effects on renal atrophy, apoptosis, fibrosis and nitric oxide/cyclic guanosine monophosphate signaling. Untreated obstructed rats showed mildly increased systolic blood pressure, marked tubular atrophy and apoptosis, tubulointerstitial macrophage infiltration and fibrosis. Plasma cyclic guanosine monophosphate levels were unaltered in untreated rats with obstruction while renal soluble guanylate cyclase mRNA expression was increased. BAY 41-8543 administration significantly increased plasma cyclic guanosine monophosphate, which was paralleled by significant decreases in systolic blood pressure, renal tubular diameter, apoptosis and renal macrophage infiltration. Also, soluble guanylate cyclase stimulation decreased tubulointerstitial fibrosis, as shown by tubulointerstitial volume, matrix protein accumulation, α-smooth muscle actin expression, collagen IV deposition and transforming growth factor-β1 mRNA expression. Soluble guanylate cyclase stimulation by BAY 41-8543 increases cyclic guanosine monophosphate production and subsequently enhances renal recovery after unilateral ureteral obstruction relief through an array of pathways. This finding suggests that soluble guanylate cyclase stimulation may serve as a novel treatment approach to restore or preserve renal structure and function in cases of obstructive kidney disease.

Differential regulation of vascular growth through cGMP/PK‐G/PK‐A signaling

Vascular smooth muscle (VSM) proliferation and migration are vital components in vessel remodeling. Cyclic nucleotide signaling in cardiovascular tissues is protective and serves as a therapeutic target. The present work analyzed the effects of the recently‐described soluble guanylate cyclase stimulator BAY 41‐2272 (BAY) on vascular growth using a balloon injury model and primary VSM cells. In rat carotid arteries, perivascular application of BAY post‐injury reduced neointimal growth by ~ 40% compared to controls after 2 weeks. In rat primary VSM cells, cyclic GMP content peaked (248x) 20 min after BAY treatment and remained elevated (140x) through 60 min. BAY did not, however, affect cyclic AMP levels or cell viability. In‐Cell Western analyses showed increases in VASP phosphorylation (p‐VASP) at Ser 239 (3x) and Ser 157 (2x), respective markers of cyclic GMP‐ and cyclic AMP‐directed protein kinases. The selective PK‐G inhibitor DT‐2 reversed the BAY‐mediated increase in p‐VASPSer 239. BAY (10μM) reduced proliferation by 40% (p&lt;0.05) after 72 h, which was reversed by PKI only. BAY also inhibited PDGF‐induced VSM cell migration by 40% (p&lt;0.001) after 6 h which was completely inhibited by DT‐2. These findings provide direct evidence for PK‐G‐specific anti‐migratory and PK‐A specific anti‐proliferative actions of BAY in VSM, supporting its therapeutic potential in vasoproliferative disorders.

Soluble Guanylate Cyclase

Arthur Kornberg, who shared with Severo Ochoa the 1959 Nobel Prize for Physiology or Medicine, stated in his autobiography that he had never met a dull enzyme.1 We strongly believe that soluble guanylate cyclase (sGC; E.C.4.6.1.2) is no exception to this. Article see p 2781 Nitric oxide (NO) plays an important physiological role as a signaling molecule as well as a cytotoxic agent. It is produced by 3 distinct NO synthases, specifically endothelial, neuronal, and inducible NO synthase. In the vasculature, endothelial NO synthase plays an important role in vascular homeostasis because NO generated in endothelial cells promotes vascular smooth muscle cell relaxation and inhibits platelet aggregation. Importantly, bioavailability of NO can be reduced in cardiovascular diseases, a condition which has been termed “endothelial dysfunction.” This phenomenon provides a rationale for therapeutic intervention. The primary target of NO is sGC, which is a heterodimeric enzyme consisting of an α- and β-subunit and a prosthetic heme group, which is located in the β-subunit. The heme group contains a ferrous iron atom (Fe2+). Binding of NO to this iron changes the conformation of the enzyme and leads to a >100-fold increase in catalytic rate (ie, the conversion of guanosine triphosphate to the second messenger cyclic guanosine monophosphate [cGMP]). The NO-induced cGMP signal modulates intracellularly the activity of several effector molecules: cGMP-dependent protein kinases, cGMP-regulated phosphodiesterases, and cGMP-gated ion channels. Of note, both heme iron oxidation (Fe3+) and heme removal render sGC unresponsive to NO (Figure). These 2 conditions could therefore provide a mechanism for “vascular smooth muscle cell dysfunction” in cardiovascular disease states, which are often characterized by marked vasoconstriction either systemically or in specific organs. Figure. Schematic illustrating 3 different forms of soluble guanylate cyclase and their respective responsiveness to nitrovasodilators, sGC stimulators (eg, BAY 41–2272), and sGC …

Single‐Dose Pharmacokinetics, Pharmacodynamics, Tolerability, and Safety of the Soluble Guanylate Cyclase Stimulator BAY 63‐2521: An Ascending‐Dose Study in Healthy Male Volunteers

The aim of the study was to assess the safety, tolerability, pharmacokinetics, and pharmacodynamics of BAY 63-2521, a new drug in development for pulmonary hypertension. Fifty-eight healthy male volunteers received a single oral dose of BAY 63-2521 (0.25-5 mg) or placebo. No serious adverse events were reported; there were no life-threatening events. Heart rate over 1 minute, an indicator of the effect of a vasodilating agent on the cardiovascular system in healthy subjects, was increased dose dependently versus placebo at BAY 63-2521 doses of 1 to 5 mg (P < .01). Mean arterial and diastolic pressures were decreased versus placebo at doses of 1 mg (P < .05) and 5 mg (P < .01). Systolic pressure was not significantly affected. BAY 63-2521 was readily absorbed and exhibited dose-proportional pharmacokinetics. The pharmacodynamic and pharmacokinetic properties of BAY 63-2521 suggest that it can offer a unique mode of action in the treatment of pulmonary hypertension.

Stimulation of soluble guanylate cyclase slows progression in anti-thy1-induced chronic glomerulosclerosis

A critical role of soluble guanylate cyclase and nitric oxide-dependent cyclic 3',5'-guanosine monophosphate (cGMP) production for glomerular matrix expansion has recently been documented in a rat model of acute anti-thy1 glomerulonephritis. The present study analyzes the renal activity of the nitric oxide-cGMP signaling cascade in and the effect of the specific soluble guanylate cyclase stimulator Bay 41-2272 on a progressive model of anti-thy1-induced chronic glomerulosclerosis. Anti-thy1 glomerulosclerosis was induced by injection of anti-thy1 antibody into uninephrectomized rats. One week after disease induction, animals were randomly assigned to chronic glomerulosclerosis, chronic glomerulosclerosis plus Bay 41-2272 (10 mg/kg body weight/day) or chronic glomerulosclerosis plus hydralazine (15 mg/kg body weight/day). In week 16, analysis included effects on systolic blood pressure, proteinuria, kidney function, glomerular and tubulointerstitial matrix protein accumulation, expression of transforming growth factor-beta1 (TGF-beta1), fibronectin and plasminogen activator inhibitor type 1 (PAI-1), macrophage infiltration, cell proliferation, basal and nitric oxide-stimulated cGMP production as well as tubulointerstitial mRNA expression of alpha 1 and beta 1 soluble guanylate cyclase. The moderately elevated systolic blood pressure seen in the chronic glomerulosclerosis group was comparably decreased by both treatments. Compared to normal controls, soluble guanylate cyclase mRNA expression and nitric oxide-stimulated cGMP production were up-regulated in the tubulointerstitium of the untreated chronic glomerulosclerosis animals, while its activity was decreased in glomeruli. Bay 41-2272 treatment enhanced glomerular and tubulointerstitial nitric oxide-cGMP signaling significantly. This went along with markedly reduced glomerular and tubulointerstitial macrophage infiltration, number of proliferating cells, matrix expression and accumulation, as well as improved kidney function. In contrast, hydralazine therapy did not significantly affect renal nitric oxide-cGMP signaling, macrophage number, cell proliferation, matrix protein expression and accumulation. Glomerular and tubulointerstitial soluble guanylate cyclase activity are discordantly altered in anti-thy1-induced chronic glomerulosclerosis. Stimulation of soluble guanylate cyclase signaling by Bay 41-2272 limits the progressive course of this model toward tubulointerstitial fibrosis and impaired renal function at least in part in a blood pressure-independent manner. The results suggest that soluble guanylate cyclase activation counteracts fibrosis and progression in chronic renal disease.

Beneficial effect of soluble guanylate cyclase stimulator BAY 41-2272 on cardiovascular remodeling in angiotensin II-induced hypertensive rats

Background BAY 41-2272 is a new type of soluble guanylate cyclase (sGC) stimulator developed recently. Although some beneficial effects of this compound on hemodynamics in hypertension and in heart failure have been reported, those on cardiovascular remodeling remains unknown. The purpose of this study is to investigate the effects of BAY 41-2272 on cardiocyte hypertrophy and extracellular matrix (ECM) formation in the heart of angiotensin II (Ang II)-induced hypertensive rats.

Expression and activity of soluble guanylate cyclase in injury and repair of anti-thy1 glomerulonephritis

Activation of soluble guanylate cyclase and generation of cyclic 3',5'-guanosine monophosphate (cGMP) is the main signal transducing event of the L-arginine-nitric oxide pathway. The present study analyzes the expression and activity of the nitric oxide-cGMP signaling cascade in and the effect of the specific soluble guanylate cyclase stimulator Bay 41-2272 on the early injury and subsequent repair phase of acute anti-thy1 glomerulonephritis. Anti-thy1 glomerulonephritis was induced by OX-7 antibody injection in rats. In protocol 1 (injury), Bay 41-2272 was given starting 6 days before antibody injection. One day after disease induction, parameters of mesangial cell injury (glomerular cell number and inducible nitric oxide synthesis) were analyzed. In protocol 2 (repair), Bay 41-2272 treatment was started one day after antibody injection. On day 7, parameters of glomerular repair [glomerular matrix score, expression of transforming growth factor (TGF)-beta1, fibronectin, and plasminogen-activator-inhibitor (PAI)-1, infiltration with macrophages and fibrinogen deposition (indicating platelet localization)] were determined. In both protocols, tail bleeding time, systolic blood pressure, plasma cGMP levels, glomerular mRNA expression of endothelial nitric oxide synthase (eNOS), alpha1 and beta1 soluble guanylate cyclase, and basal and nitric oxide-stimulated glomerular cGMP production were analyzed. Bay 41-2272 prolonged bleeding time, reduced blood pressure, and increased plasma cGMP levels in both protocols. In the injury experiment, disease induction increased inducible nitric oxide synthesis and reduced glomerular cell number, while expression and activity of soluble guanylate cyclase was almost completely diminished. Bay 41-2272 did not affect parameters of mesangial cell injury and glomerular soluble guanylate cyclase expression and activity. In the repair protocol, expression and activity of soluble guanylate cyclase was markedly increased by disease. Bay 41-2272 further enhanced soluble guanylate cyclase expression and activity. This went along with significant reductions in proteinuria, glomerular matrix accumulation, expression of TGF-beta1, fibronectin, and PAI-1, macrophage infiltration and fibrinogen deposition as compared to the untreated anti-thy1 animals. Glomerular nitric oxide signaling via cGMP is markedly impaired during injury of anti-thy1 glomerulonephritis, while it is highly up-regulated during subsequent repair. Further pharmacologic soluble guanylate cyclase stimulation limits glomerular TGF-beta overexpression and matrix expansion, suggesting that the soluble guanylate cyclase enzyme represents an important antifibrotic pathway in glomerular disease.

Cardiorenal actions of the novel direct soluble guanylate cyclase stimulator BAY 41–2272 in experimental congestive heart failure in comparison to nitroglycerin

Cardiorenal actions of the novel direct soluble guanylate cyclase stimulator BAY 41–2272 in experimental congestive heart failure in comparison to nitroglycerin