Stimulators and activators of soluble guanylate cyclase: review and potential therapeutic indications

Genetic Factors for Coronary Heart Disease and Their Mechanisms: A Meta-Analysis and Comprehensive Review of Common Variants from Genome-Wide Association Studies

Genome-wide association studies (GWAS) have discovered 163 loci related to coronary heart disease (CHD). Most GWAS have emphasized pathways related to single-nucleotide polymorphisms (SNPs) that reached genome-wide significance in their reports, while identification of CHD pathways based on the combination of all published GWAS involving various ethnicities has yet to be performed. We conducted a systematic search for articles with comprehensive GWAS data in the GWAS Catalog and PubMed, followed by a meta-analysis of the top recurring SNPs from ≥2 different articles using random or fixed-effect models according to Cochran Q and I2 statistics, and pathway enrichment analysis. Meta-analyses showed significance for 265 of 309 recurring SNPs. Enrichment analysis returned 107 significant pathways, including lipoprotein and lipid metabolisms (rs7412, rs6511720, rs11591147, rs1412444, rs11172113, rs11057830, rs4299376), atherogenesis (rs7500448, rs6504218, rs3918226, rs7623687), shared cardiovascular pathways (rs72689147, rs1800449, rs7568458), diabetes-related pathways (rs200787930, rs12146487, rs6129767), hepatitis C virus infection/hepatocellular carcinoma (rs73045269/rs8108632, rs56062135, rs188378669, rs4845625, rs11838776), and miR-29b-3p pathways (rs116843064, rs11617955, rs146092501, rs11838776, rs73045269/rs8108632). In this meta-analysis, the identification of various genetic factors and their associated pathways associated with CHD denotes the complexity of the disease. This provides an opportunity for the future development of novel CHD genetic risk scores relevant to personalized and precision medicine.

Responses in Blood Pressure and Kidney Function to Soluble Guanylyl Cyclase Stimulation or Activation in Normal and Diabetic Rats

Introduction:

Agonists of soluble guanylate cyclase (sGC) are being developed as treatment for cardiovascular disease. Most effects of nitric oxide (NO) on glomerular and tubular function are mediated through sGC but whether sGC agonists mimic these effects is unknown.

Methods:

Renal clearance and micropuncture studies were performed in Wistar-Froemter rats (WF), with or without streptozotocin diabetes (STZ-WF), and in Goto-Kakizaki rats (GK) with mild type-2 diabetes to test for acute effects of the sGC “stimulator” BAY 41-2272, which synergizes with endogenous NO, and the “activator” runcaciguat, which generates cGMP independent of NO.

Results:

Both sGC agonists reduced arterial blood pressure (MAP). For MAP reductions <10% the drugs increased GFR in WF and STZ-WF but not in GK. Larger MAP reductions outweighed this effect and GFR declined, with better preserved GFR in STZ-WF. Changes in GFR could not be accounted for by changes in RBF, suggesting parallel changes in ultrafiltration pressure and/or ultrafiltration coefficient. The doses chosen for micropuncture in WF and GK reduced MAP by 2–10% and the net effect on single nephron GFR and ultrafiltration pressure was neutral. Effects of the drugs on tubular reabsorption were dominated by declining MAP and no natriuretic effect observed at any dose.

Discussion/Conclusion:

sGC agonists impact kidney function directly and because they reduce MAP. The direct tendency to increase GFR is most apparent for MAP reductions <10%. The direct effect is otherwise subtle and overridden when MAP declines more. Effects of sGC agonists on tubular reabsorption are dominated by effects on MAP.

Nitric-Oxide-Modulatory Materials for Biomedical Applications

Nitric oxide (NO) is an endogenous signaling molecule that participates in various physiological and biological pathways associated with vasodilation, immune response, and cell apoptosis. Interestingly, NO has versatile and distinct functions in vivo depending on its concentration and the duration of exposure; it aids cellular proliferation at nanomolar concentrations but causes cellular death at micromolar concentrations. Therefore, achieving the precise and on-demand modulation of microenvironmental NO concentrations has become a major research target in biomedical fields. To this end, many studies have investigated feasible means for developing functional moieties that can either exogenously donate or selectively scavenge NO. However, these advances are limited by poor stability and a lack of target specificity, which represent two significant obstacles regarding the spatiotemporal adjustment of NO in vivo. Our group has addressed this issue by contributing to the development of next-generation NO-modulatory materials over the past decade. Over this period, we utilized various polymeric, inorganic, and hybrid systems to enhance the bioavailability of traditional NO donors or scavengers in an attempt to maximize their clinical usage while also minimizing their unwanted side effects. In this Account, strategies regarding the rational design of NO-modulatory materials are first summarized and discussed, depending on their specific purposes. These strategies include chemical approaches for encapsulating traditional NO donors inside specific vehicles; this prevents spontaneous NO release and allows said donors to be exposed on-demand, under a certain stimulus. The current status of these approaches and the recent contributions of other groups are also comprehensively discussed here to ensure an objective understanding of the topic. Moreover, in this paper, we discuss strategies for the selective depletion of NO from local inflammatory sites, where the overproduction of NO is problematic. Finally, the major challenges for current NO-modulatory systems are discussed, and requirements are outlined that need to be tackled to achieve their future therapeutic development. Starting from this current, relatively early stage of development, we propose that, through continuous efforts to surmount existing challenges, it will be possible in the future to achieve clinical translations regarding NO-modulatory systems. This Account provides insightful guidelines regarding the rational design of NO-modulatory systems for various biomedical applications. Moreover, it can facilitate the achievement of previously unattainable goals while revolutionizing future therapeutics.

Highly Diluted Antibodies to eNOS Restore Endothelium Function in Aortic Rings From Hypertensive Rats

Background

Nitric oxide (NO) as a vaso- and cardio-protective agent could reduce vasomotor dysfunction in different cardiovascular diseases. One of the current therapeutics targeted at NO availability in the vascular wall are highly diluted antibodies to endothelial NO-synthase (eNOS). This drug has previously shown its endothelium-protective effect and effectiveness in reducing hypertension. Current study was dedicated to evaluate the direct impact of highly diluted antibodies to eNOS on the vessel constriction and dilation ex vivo.

Methods

For that purpose, we used thoracic aortas dissected from spontaneously hypertensive (SHR) rats. Endothelium-dependent relaxation in the presence of highly diluted antibodies to eNOS (1 mL) was examined after phenylephrine-induced pre-constriction of the aorta rings in response to gradually increased acetylcholine concentration (1 nM to 10 µM).

Results

Highly diluted antibodies to eNOS enhanced acetylcholine-induced relaxation in a statistically significant manner. Moreover, it was demonstrated that observed effect was similar to perindopril, a well-known angiotensin-converting-enzyme inhibitor, which works through relaxing and widening blood vessels.

Conclusions

Our findings indicate that highly diluted antibodies to eNOS restored impaired endothelium function, as demonstrated by increased relaxation of SHR rats aorta rings. The revealed results suggest beneficial effect of highly diluted antibodies to eNOS to ameliorate hypertension and related diseases.

Review - Nutraceuticals Can Target Asthmatic Bronchoconstriction: NADPH Oxidase-Dependent Oxidative Stress, RhoA and Calcium Dynamics

Activation of various isoforms of NADPH oxidase contributes to the pathogenesis of asthma at multiple levels: promoting hypercontractility, hypertrophy, and proliferation of airway smooth muscle; enabling lung influx of eosinophils via VCAM-1; and mediating allergen-induced mast cell activation. Free bilirubin, which functions physiologically within cells as a feedback inhibitor of NADPH oxidase complexes, has been shown to have a favorable impact on each of these phases of asthma pathogenesis. The spirulina chromophore phycocyanobilin (PhyCB), a homolog of bilirubin’s precursor biliverdin, can mimic the inhibitory impact of biliverdin/bilirubin on NADPH oxidase activity, and spirulina’s versatile and profound anti-inflammatory activity in rodent studies suggests that PhyCB may have potential as a clinical inhibitor of NADPH oxidase. Hence, spirulina or PhyCB-enriched spirulina extracts merit clinical evaluation in asthma. Promoting biosynthesis of glutathione and increasing the expression and activity of various antioxidant enzymes – as by supplementing with N-acetylcysteine, Phase 2 inducers (eg, lipoic acid), selenium, and zinc – may also blunt the contribution of oxidative stress to asthma pathogenesis. Nitric oxide (NO) and hydrogen sulfide (H₂S) work in various ways to oppose pathogenic mechanisms in asthma; supplemental citrulline and high-dose folate may aid NO synthesis, high-dose biotin may mimic and possibly potentiate NO’s activating impact on soluble guanylate cyclase, and NAC and taurine may boost H₂S synthesis. The amino acid glycine has a hyperpolarizing effect on airway smooth muscle that is bronchodilatory. Insuring optimal intracellular levels of magnesium may modestly blunt the stimulatory impact of intracellular free calcium on bronchoconstriction. Nutraceutical regimens or functional foods incorporating at least several of these agents may have utility as nutraceutical adjuvants to standard clinical management of asthma.

Discovery of CYR715: A novel carboxylic acid-containing soluble guanylate cyclase stimulator

Soluble guanylate cyclase (sGC) is a clinically validated therapeutic target in the treatment of pulmonary hypertension. Modulators of sGC have the potential to treat diseases that are affected by dysregulation of the NO-sGC-cGMP signal transduction pathway. This letter describes the SAR efforts that led to the discovery of CYR715, a novel carboxylic acid-containing sGC stimulator, with an improved metabolic profile relative to our previously described stimulator, IWP-051. CYR715 addressed potential idiosyncratic drug toxicity (IDT) liabilities associated with the formation of reactive, migrating acyl glucuronides (AG) found in related carboxylic acid-containing analogs and demonstrated high oral bioavailability in rat and dose-dependent hemodynamic pharmacology in normotensive Sprague-Dawley rats.

Backbone and side chain NMR assignments of the H-NOX domain from Nostoc sp. in complex with BAY58-2667 (cinaciguat)

Soluble guanylate cyclase (sGC) enzyme is activated by the gaseous signaling agent nitric oxide (NO) and triggers the conversion of GTP (guanosine 5'-triphosphate) to cGMP (cyclic guanylyl monophosphate). It contains the heme binding H-NOX (heme-nitric oxide/oxygen binding) domain which serves as the sensor of NO and it is highly conserved across eukaryotes and bacteria as well. Many research studies focus on the synthesis of chemical compounds bearing possible therapeutic action, which mimic the heme moiety and activate the sGC enzyme. In this study, we report a preliminary solution NMR (Nuclear Magnetic Resonance) study of the H-NOX domain from Nostoc sp. cyanobacterium in complex with the chemical sGC activator cinaciguat (BAY58-2667). An almost complete sequence-specific assignment of its 1H, 15N and 13C resonances was obtained and its secondary structure predicted by TALOS+.

Endothelial Dysfunction in Chronic Kidney Disease, from Biology to Clinical Outcomes: A 2020 Update

The vascular endothelium is a dynamic, functionally complex organ, modulating multiple biological processes, including vascular tone and permeability, inflammatory responses, thrombosis, and angiogenesis. Endothelial dysfunction is a threat to the integrity of the vascular system, and it is pivotal in the pathogenesis of atherosclerosis and cardiovascular disease. Reduced nitric oxide (NO) bioavailability is a hallmark of chronic kidney disease (CKD), with this disturbance being almost universal in patients who reach the most advanced phase of CKD, end-stage kidney disease (ESKD). Low NO bioavailability in CKD depends on several mechanisms affecting the expression and the activity of endothelial NO synthase (eNOS). Accumulation of endogenous inhibitors of eNOS, inflammation and oxidative stress, advanced glycosylation products (AGEs), bone mineral balance disorders encompassing hyperphosphatemia, high levels of the phosphaturic hormone fibroblast growth factor 23 (FGF23), and low levels of the active form of vitamin D (1,25 vitamin D) and the anti-ageing vasculoprotective factor Klotho all impinge upon NO bioavailability and are critical to endothelial dysfunction in CKD. Wide-ranging multivariate interventions are needed to counter endothelial dysfunction in CKD, an alteration triggering arterial disease and cardiovascular complications in this high-risk population.

Possible mechanisms mediating the protective effect of cilostazol in L-arginine induced acute pancreatitis in rats: role of cGMP, cAMP, and HO-1

Acute pancreatitis (AP) is an inflammatory disorder with a high mortality rate. Cilostazol is a selective phosphodiesterase-3 inhibitor drug that is commonly used as an antiplatelet, antithrombotic, and vasodilator drug. It exhibits antioxidant, anti-inflammatory, and anti-apoptotic activities, but its effect on AP has not been fully elucidated yet. The present study aimed to investigate the effects of cilostazol on L-arginine-induced AP and the possible protective mechanisms. A rat model of AP was established by a single i.p. injection of 3-g/kg L-arginine on day 13 of the experiment. The treated groups received a single daily oral dose of either 100 or 300 mg/kg/day for 14 consecutive days. Rats with AP showed histopathological changes of pancreatic tissue injury together with increased serum amylase enzyme activity and decreased serum insulin, pancreatic adiponectin, and cGMP levels. Moreover, AP rats showed increased pancreatic inflammatory biomarker (TNF-α, VCAM-1, and MPO) levels with decreased anti-inflammatory IL-10 levels. In addition, oxidative stress biomarkers (MDA and NO) were increased in AP with decreased antioxidant SOD activity and GSH level. Moreover, HO-1 immunostaining was increased in the AP group. Cilostazol pretreatment reversed the histopathological change; decreased the amylase activity and the levels of TNF-α, VCAM-1, and MPO; and increased the levels of insulin, adiponectin, cGMP, cAMP, and IL-10. Moreover, cilostazol decreased MDA and NO but increased SOD and GSH. Lastly, cilostazol increased the HO-1 immunostaining more than in the AP group. These data suggest that cilostazol protects against L-arginine-induced AP, which may be related to an increase in cGMP, cAMP, and upregulation of HO-1 with subsequent anti-inflammatory and antioxidant properties.

Therapies that enhance pulmonary vascular NO-signaling in the neonate

There are several pulmonary hypertensive diseases that affect the neonatal population, including persistent pulmonary hypertension of the newborn (PPHN) and bronchopulmonary dysplasia (BPD)-associated pulmonary hypertension (PH). While the indication for inhaled nitric oxide (iNO) use is for late-preterm and term neonates with PPHN, there is a suboptimal response to this pulmonary vasodilator in ~40% of patients. Additionally, there are no FDA-approved treatments for BPD-associated PH or for preterm infants with PH. Therefore, investigating mechanisms that alter the nitric oxide-signaling pathway has been at the forefront of pulmonary vascular biology research. In this review, we will discuss the various mechanistic pathways that have been targets in neonatal PH, including NO precursors, soluble guanylate cyclase modulators, phosphodiesterase inhibitors and antioxidants. We will review their role in enhancing NO-signaling at the bench, in animal models, as well as highlight their role in the treatment of neonates with PH.

Heat shock protein 90 regulates soluble guanylyl cyclase maturation by a dual mechanism

The enzyme soluble guanylyl cyclase (sGC) is a heterodimer composed of an α subunit and a heme-containing β subunit. It participates in signaling by generating cGMP in response to nitric oxide (NO). Heme insertion into the β1 subunit of sGC (sGCβ) is critical for function, and heat shock protein 90 (HSP90) associates with heme-free sGCβ (apo-sGCβ) to drive its heme insertion. Here, we tested the accuracy and relevance of a modeled apo-sGCβ-HSP90 complex by constructing sGCβ variants predicted to have an impaired interaction with HSP90. Using site-directed mutagenesis, purified recombinant proteins, mammalian cell expression, and fluorescence approaches, we found that (i) three regions in apo-sGCβ predicted by the model mediate direct complex formation with HSP90 both in vitro and in mammalian cells; (ii) such HSP90 complex formation directly correlates with the extent of heme insertion into apo-sGCβ and with cyclase activity; and (iii) apo-sGCβ mutants possessing an HSP90-binding defect instead bind to sGCα in cells and form inactive, heme-free sGC heterodimers. Our findings uncover the molecular features of the cellular apo-sGCβ-HSP90 complex and reveal its dual importance in enabling heme insertion while preventing inactive heterodimer formation during sGC maturation.

New Insight into the Role of Nitric Oxide Pathways in Pancreas

Nitric oxide (NO) is generated by a family of enzymes termed NO synthases (NOS) that convert L-arginine to NO and citrulline. The role of NO as an important biological mediator and recognition of the pathophysiological significance of superoxides/NO interaction has led to an intensive research and development of therapies based on the interception of the NO signaling cascade in the pancreatitis course. However, the presence and localization of the NO-generating enzymes in various organs including pancreas are subject to controversy. We assumed that this controversy might reflect rather the diversity of experimental approaches and an insufficient sensitivity of the methods used. Applying tyramide signal amplification (TSA) immunohistochemical technology, we were able detect all three NOS isoforms both in exocrine and endocrine compartments and in the vasculature in the normal pancreas and in pancreatitis. This also allowed us to demonstrate that oxidative stress runs ahead of NOS up-regulation, which implies that the NO enhancement in the course of pancreatitis is likely to be an adaptive mechanism aimed at maintaining the homeostatic cellular level of the bioactive NO. The aims of this minireview are to describe normal intrapancreatic NO pathways and the role of NO in the pancreatitis course.

Comparative Studies of the Dynamics Effects of BAY60-2770 and BAY58-2667 Binding with Human and Bacterial H-NOX Domains

Soluble guanylate cyclase (sGC) is a key enzyme implicated in various physiological processes such as vasodilation, thrombosis and platelet aggregation. The enzyme’s Heme-Nitric oxide/Oxygen (H-NOX) binding domain is the only sensor of nitric oxide (NO) in humans, which on binding with NO activates sGC to produce the second messenger cGMP. H-NOX is thus a hot target for drug design programs. BAY60-2770 and BAY58-2667 are two widely studied activators of sGC. Here we present comparative molecular dynamics studies to understand the molecular details characterizing the binding of BAY60-2770 and BAY58-2667 with the human H-NOX (hH-NOX) and bacterial H-NOX (bH-NOX) domains. HartreeFock method was used for parametrization of both the activators. A 50 ns molecular dynamics (MD) simulation was run to identify the functionally critical regions of the H-NOX domains. The CPPTRAJ module was used for analysis. BAY60-2770 on binding with bH-NOX, triggered rotational movement in signaling helix F and significant dynamicity in loops α and β, but in hH-NOX domain the compound showed relatively lesser aforementioned structural fluctuations. Conversely, hH-NOX ligated BAY58-2667 experienced highest transitions in its helix F due to electrostatic interactions with D84, T85 and R88 residues which are not conserved in bH-NOX. These conformational transformations might be essential to communicate with downstream PAS, CC and cyclase domains of sGC. Comparative MD studies revealed that BAY bound bHNOX dynamics varied from that of hH-NOX, plausibly due to some key residues such as R40, F74 and Y112 which are not conserved in bacteria. These findings will help to the design of novel drug leads to cure diseases associated to human sGC.

ANMCO Position Paper: long-term follow-up of patients with pulmonary thromboembolism

Venous thromboembolism (VTE), including pulmonary embolism and deep venous thrombosis, is the third most common cause of cardiovascular death. The management of the acute phase of VTE has already been described in several guidelines. However, the management of the follow-up (FU) of these patients has been poorly defined. This consensus document, created by the Italian cardiologists, wants to clarify this issue using the currently available evidence in VTE. Clinical and instrumental data acquired during the acute phase of the disease are the cornerstone for planning the FU. Acquired or congenital thrombophilic disorders could be identified in apparently unprovoked VTE during the FU. In other cases, an occult cancer could be discovered after a VTE. The main targets of the post-acute management are to prevent recurrence of VTE and to identify the patients who can develop a chronic thromboembolic pulmonary hypertension. Knowledge of pathophysiology and therapeutic approaches is fundamental to decide the most appropriate long-term treatment. Moreover, prognostic stratification during the FU should be constantly updated on the basis of the new evidence acquired. Currently, the cornerstone of VTE treatment is represented by both the oral and the parenteral anticoagulation. Novel oral anticoagulants should be an interesting alternative in the long-term treatment.

Adverse Drug Reactions in the Intensive Care Unit

Adverse drug reactions (ADRs) are undesirable effects of medications used in normal doses [1]. ADRs can occur during treatment in an intensive care unit (ICU) or result in ICU admissions. A meta-analysis of 4139 studies suggests the incidence of ADRs among hospitalized patients is 17% [2]. Because of underreporting and misdiagnosis, the incidence of ADRs may be much higher and has been reported to be as high as 36% [3]. Critically ill patients are at especially high risk because of medical complexity, numerous high-alert medications, complex and often challenging drug dosing and medication regimens, and opportunity for error related to the distractions of the ICU environment [4]. Table 1 summarizes the ADRs included in this chapter.

Effects of dynamic shear and transmural pressure on wall shear stress sensitivity in collecting lymphatic vessels

Given the known mechanosensitivity of the lymphatic vasculature, we sought to investigate the effects of dynamic wall shear stress (WSS) on collecting lymphatic vessels while controlling for transmural pressure. Using a previously developed ex vivo lymphatic perfusion system (ELPS) capable of independently controlling both transaxial pressure gradient and average transmural pressure on an isolated lymphatic vessel, we imposed a multitude of flow conditions on rat thoracic ducts, while controlling for transmural pressure and measuring diameter changes. By gradually increasing the imposed flow through a vessel, we determined the WSS at which the vessel first shows sign of contraction inhibition, defining this point as the shear stress sensitivity of the vessel. The shear stress threshold that triggered a contractile response was significantly greater at a transmural pressure of 5 cmH2O (0.97 dyne/cm(2)) than at 3 cmH2O (0.64 dyne/cm(2)). While contraction frequency was reduced when a steady WSS was applied, this inhibition was reversed when the applied WSS oscillated, even though the mean wall shear stresses between the conditions were not significantly different. When the applied oscillatory WSS was large enough, flow itself synchronized the lymphatic contractions to the exact frequency of the applied waveform. Both transmural pressure and the rate of change of WSS have significant impacts on the contractile response of lymphatic vessels to flow. Specifically, time-varying shear stress can alter the inhibition of phasic contraction frequency and even coordinate contractions, providing evidence that dynamic shear could play an important role in the contractile function of collecting lymphatic vessels.

Increased Long-Term Mortality among Black CABG Patients Receiving Preoperative Inotropic Agents

The aim of this study was to examine racial differences in long-term mortality after coronary artery bypass grafting (CABG), stratified by preoperative use of inotropic agents. Black and white patients who required preoperative inotropic support prior to undergoing CABG procedures between 1992 and 2011 were compared. Mortality probabilities were computed using the Kaplan-Meier product-limit method. Hazard ratios (HR) and 95% confidence intervals (CI) were computed using a Cox regression model. A total of 15,765 patients underwent CABG, of whom 211 received preoperative inotropic agents within 48 hours of surgery. Long-term mortality differed by race (black versus white) among preoperative inotropic category (inotropes: adjusted HR = 1.6, 95% CI = 1.009–2.4; no inotropes: adjusted HR = 1.15, 95% CI = 1.08–1.2; P_interaction < 0.0001). Our study identified an independent preoperative risk-factor for long-term mortality among blacks receiving CABG. This outcome provides information that may be useful for surgeons, primary care providers, and their patients.

Involvement of H1 and H2 receptors and soluble guanylate cyclase in histamine-induced relaxation of rat mesenteric collecting lymphatics

OBJECTIVE

This study investigated the roles of the H1 and H2 histamine receptors, NO synthase, and sGC cyclase in histamine-induced modulation of rat mesenteric collecting lymphatic pumping.

METHODS

Isolated rat mesenteric collecting lymphatics were treated with 1- to 100-μM histamine. Histamine receptors were blocked with either the H1 antagonist mepyramine or the H2 antagonist cimetidine. The role of NO/sGC signaling was tested using the arginine analog L-NAME, the sGC inhibitor ODQ, and SNP as a positive control.

RESULTS

Histamine applied at 100 μM decreased tone and CF of isolated rat mesenteric collecting lymphatics. Pharmacologic blockade of either H1 or H2 histamine receptors significantly inhibited the response to histamine. Pretreatment with ODQ, but not L-NAME, completely inhibited the histamine-induced decrease in tone. ODQ pretreatment also significantly inhibited SNP-induced lymphatic relaxation.

CONCLUSIONS

H1 and H2 histamine receptors are both involved in histamine-induced relaxation of rat mesenteric collecting lymphatics. NO synthesis does not appear to contribute to the histamine-induced response. However, sGC is critical for the histamine-induced decrease in tone and contributes to the drop in CF.

Reduced vascular responses to soluble guanylyl cyclase but increased sensitivity to sildenafil in female rats with type 2 diabetes

Impaired nitric oxide (NO), soluble guanylyl cyclase (sGC), and cyclic guanosine monophosphate (cGMP) signaling (NO-sGC-cGMP) has been implicated in the pathogenesis of diabetic vascular dysfunction. Efforts to directly target this signaling have led to the development of sGC agonists that activate the heme group of sGC (stimulators) or preferentially activate sGC when the heme is oxidized (activators). In this study, we hypothesized that resistance arteries from female rats with spontaneous type 2 diabetes (Goto-Kakizaki rats, GK) would have reduced vasodilatory responses to heme-dependent sGC activation and increased responses to heme-independent sGC activation compared with control rats (Wistar). Endothelium-dependent and -independent relaxation was assessed in isolated segments from mesenteric resistance arteries (MA) mounted in a wire myograph. GK MA had reduced responses to acetylcholine (pEC50: 7.96 ± 0.06 vs. 7.66 ± 0.05, P < 0.05) and sodium nitroprusside (pEC50: 8.34 ± 0.05 vs. 7.77 ± 0.04, P < 0.05). There were no group differences in 8-bromoguanosine cGMP-induced relaxation and protein kinase G1 expression (P > 0.05). GK MA had attenuated responses to BAY 41-2272 (heme-dependent sGC stimulator; pEC50: 7.56 ± 0.05 vs. 6.93 ± 0.06, P < 0.05) and BAY 58-2667 (heme-independent sGC activator; pEC50: 10.82 ± 0.07 vs. 10.27 ± 0.08, P < 0.05) and increased sensitivity to sildenafil [phosphodiesterase 5 (PDE5) inhibitor; pEC50: 7.89 ± 0.14 vs. 8.25 ± 0.13, P < 0.05]. Isolated resistance arteries from female rats of reproductive age that spontaneously develop type 2 diabetes have increased sensitivity to PDE5 inhibition and reduced responsiveness to sGC activators and stimulators.

Cyclic nucleotide signalling in kidney fibrosis

Kidney fibrosis is an important factor for the progression of kidney diseases, e.g., diabetes mellitus induced kidney failure, glomerulosclerosis and nephritis resulting in chronic kidney disease or end-stage renal disease. Cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) were implicated to suppress several of the above mentioned renal diseases. In this review article, identified effects and mechanisms of cGMP and cAMP regarding renal fibrosis are summarized. These mechanisms include several signalling pathways of nitric oxide/ANP/guanylyl cyclases/cGMP-dependent protein kinase and cAMP/Epac/adenylyl cyclases/cAMP-dependent protein kinase. Furthermore, diverse possible drugs activating these pathways are discussed. From these diverse mechanisms it is expected that new pharmacological treatments will evolve for the therapy or even prevention of kidney failure.

Soluble guanylate cyclase: a new therapeutic target for pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension

Nitric oxide (NO) activates soluble guanylate cyclase (sGC) by binding its prosthetic heme group, thereby catalyzing cyclic guanosine monophosphate (cGMP) synthesis. cGMP causes vasodilation and may inhibit smooth muscle cell proliferation and platelet aggregation. The NO-sGC-cGMP pathway is disordered in pulmonary arterial hypertension (PAH), a syndrome in which pulmonary vascular obstruction, inflammation, thrombosis, and constriction ultimately lead to death from right heart failure. Expression of sGC is increased in PAH but its function is reduced by decreased NO bioavailability, sGC oxidation and the related loss of sGC's heme group. Two classes of sGC modulators offer promise in PAH. sGC stimulators (e.g., riociguat) require heme-containing sGC to catalyze cGMP production, whereas sGC activators (e.g., cinaciguat) activate heme-free sGC. Riociguat is approved for PAH and yields functional and hemodynamic benefits similar to other therapies. Its main serious adverse effect is dose-dependent hypotension. Riociguat is also approved for inoperable chronic thromboembolic pulmonary hypertension.

L-arginine-NO-cGMP signalling pathway in pancreatitis

The role of nitric oxide (NO) in the human pancreas and in pancreatitis still remains controversial. Furthermore, conflicting conclusions have been reached by different laboratories about the localization of the NO-generating enzyme (NO synthase, NOS) in the pancreas. Here, we investigated the co-expression of NOS with enzymes involved in regulation of NO signalling in the normal human pancreas and in pancreatitis. We found that the whole NO signalling machinery was up-regulated in pancreatitis, especially within the exocrine compartment. Furthermore, the exocrine parenchymal cells revealed higher levels of oxidative stress markers, nitrotyrosine and 8-hydroxyguanosine, in pancreatitis, which reflects the exceptional susceptibility of the exocrine parenchyma to oxidative stress. This study provides a direct link between oxidative stress and the enzymatic control of the NO bioavailability at the cellular level and endows with further insight into fundamental mechanisms underlying pancreatic disorders associated with disruptions in the L-arginine-NO-cGMP signalling enzyme cascade.

Effects of somatothermal far-infrared ray on primary dysmenorrhea: a pilot study

The purpose of this study was to assess the beneficial effects of using a far-infrared (FIR) belt on the management of patients with primary dysmenorrhea. This is the first study to determine the efficacy of somatothermal FIR using a parallel-arm randomized sham-controlled and double-blinded design with objective physical evidence and psychometric self-reports. Fifty-one Taiwanese women with primary dysmenorrhea were enrolled in the study. Results indicate that there was an increased abdominal temperature of 0.6°C and a 3.27% increase in abdominal blood flow in the FIR group (wearing FIR belt) compared to those in the control group (wearing sham belt). Verbal rating scale and numeric rating scale scores in the FIR group were both lower than those in the control group. Compared to the blank group (wearing no belt), the average dysmenorrhea pain duration of the FIR group was significantly reduced from 2.5 to 1.8 days, but there was no significant difference in the control group. These results demonstrate that the use of a belt made of far-infrared ceramic materials can reduce primary dysmenorrhea.