Buxu Tongyu Granule Alleviates Myocardial Ischemia by Activating Vascular Smooth Muscle Cell Soluble Guanylate Cyclase to Inhibit Abnormal Vasomotion

Myocardial ischemia is a serious threat to human health,and vascular dysfunction is its main cause.Buxu Tongyu(BXTY)Granule is an effective traditional Chinese medicine(TCM)for treating myocardial ischemia.However,the underlying mechanism of BXTY is still unclear.In this study,we demonstrate that BXTY ameliorates myocardial ischemia by activating the soluble guanylate cyclase(sGC)-30,50-cyclic guanosine monophosphate(cGMP)-protein kinase G(PKG)signaling pathway in vascular smooth muscle cells(VSMCs)to dilate the arteries.BXTY was given by gavage for ten consecutive days before establishing an animal model of acute myocardial ischemia in mice via the intraperitoneal injection of pituitrin.The results showed that BXTY alleviated the symptoms of myocardial ischemia induced by pituitrin in mice,including electrocardiogram abnormalities and changes in plasma enzymes.In addition,BXTY dilated pre-constricted blood vessels and inhibited the vasoconstriction of the superior mesenteric artery in a dose-dependent but endothelial-independent manner.These effects were eliminated by preincubating vascular rings with the sGC inhibitors NS 2028 or ODQ,or with the PKG inhibitor KT 5823.Moreover,BXTY increased the protein expression of sGC-b1 and the intracellular second messenger cGMP level in mouse aortic vascular smooth muscle cells(MOVAs).NS 2028 or ODQ reversed these effects of BXTY.The expression level of the cGMP downstream effector protein PKG-1 increased after treating MOVAs with BXTY.NS 2028,ODQ,or KT 5823 also reversed this effect of BXTY.In conclusion,BXTY can improve the symptoms of acute myocardial ischemia in mice,and activating the sGC-cGMP-PKG pathway in VSMCs to induce vasodilation is its key pharmacodynamic mechanism.

Safety and efficacy of soluble guanylate cyclase stimulators in patients with heart failure: A systematic review and meta-analysis

BACKGROUND The utility of novel oral soluble guanylate cyclase(sGC)stimulators(vericiguat and riociguat),in patients with reduced or preserved ejection fraction heart failure(HFrEF/HFpEF)is currently unclear.AIM To determine the efficacy and safety of sGC stimulators in HF patients.METHODS Multiple databases were searched to identify relevant randomized controlled trials(RCTs).Data on the safety and efficacy of sGC stimulators were compared using relative risk ratio(RR)on a random effect model.RESULTS Six RCTs,comprising 5604 patients(2801 in sGC stimulator group and 2803 placebo group)were included.The primary endpoint(a composite of cardiovascular mortality and first HF-related hospitalization)was significantly reduced in patients receiving sGC stimulators compared to placebo[RR 0.92,95%confidence interval(CI):0.85-0.99,P=0.02].The incidence of total HF-related hospitalizations were also lower in sGC group(RR 0.91,95%CI:0.86-0.96,P=0.0009),however,sGC stimulators had no impact on all-cause mortality(RR 0.96,95%CI:0.86-1.07,P=0.45)or cardiovascular mortality(RR 0.94,95%CI:0.83-1.06,P=0.29).The overall safety endpoint(a composite of hypotension and syncope)was also similar between the two groups(RR 1.50,95%CI:0.93-2.42,P=0.10).By contrast,a stratified subgroup analysis adjusted by type of sGC stimulator and HF(vericiguat vs riociguat and HFrEF vs HFpEF)showed near identical rates for all safety and efficacy endpoints between the two groups at a mean follow-up of 19 wk.For the primary composite endpoint,the number needed to treat was 35,the number needed to harm was 44.CONCLUSION The use of vericiguat and riociguat in conjunction with standard HF therapy,shows no benefit in terms of decreasing HF-related hospitalizations or mortality.

Isolation,Purification and Spectral Characteristics of Soluble Guanylate Cyclase from Bovine Lung

We isolated and purified high purity and high activity soluble Guanylate cyclase(sGC) from bovine lung. The electronic absorption and resonance Raman spectra of the ferrous and ferric forms of sGC were recorded. In the ferrous state of sGC, the electronic absorption spectra showed a sharp peak at 431 nm and a single broad peak in the α/β region at 559 nm. The resonance Raman spectra of sGC(ferrous) showed a stronger band at 1357 cm -1 and a single peak at 1473 cm -1 . For the ferric form of sGC, the Soret band was at 390 nm and resonance Raman peak was at 1375 cm -1 . These spectra show that the heme iron of the ferrous and ferric sGC are all 5 coordination and high spin.

Expression of nitric oxide synthase and guanylate cyclase in the human ciliary body and trabecular meshwork

Background The role played by the nitric oxide （NO） signaling pathway in the aqueous humor dynamics is still unclear.This study was designed to investigate the expression and distribution of NO synthase （NOS） isoforms and guanylate cyclase （GC） in human ciliary body,trabecular meshwork and the Schlemm＇s canal.Methods Twelve eyes after corneal transplantation were used.Expression of three NOS isoforms （i.e.neuronal NOS （nNOS）,inducible NOS （iNOS） and endothelial NOS （eNOS）） and GC were assessed in 10 eyes by immunohistochemical staining using monoclonal or polyclonal antibody of NOS and GC.Ciliary bodies were dissected free and the total proteins were extracted.Western blotting was performed to confirm the protein expression of 3 NOS isoforms and GC.Results Expression of 3 NOS isoforms and GC were observed in the ciliary epithelium,ciliary muscle,trabecular meshwork and the endothelium of the Schlemm＇s canal.Immunoreactivity of nNOS was detected mainly along the apical cytoplasmic junction of the non-pigmented epithelium （NPE） and pigmented epithelial （PE） cells.Protein expressions of 3 NOS isoforms and GC were confirmed in isolated human ciliary body by Western blotting.Conclusions The expression of NOS isoforms and GC in human ciliary body suggest the possible involvement of NO and cyclic guanosine monophosphate （cyclic GMP,cGMP） signaling pathway in the ciliary body,and may play a role in both processes of aqueous humor formation and drainage.

The roles of cysteines in the heme domain of human soluble guanylate cyclase

Soluble guanylate cyclase（sGC） is a critical heme-containing enzyme involved in NO signaling.The dimerization of sGC subunits is necessary for its bioactivity and its mechanism is a striking and an indistinct issue.The roles of heme domain cysteines of the sGC on the dimerization and heme binding were investigated herein.The site-directed mutations of three conserved cysteines（C78A,C122A and C174S） were studied systematically and the three mutants were characterized by gel filtration analysis,UV-vis spectroscopy and heme transfer examination.Cys78 was involved in heme binding but not referred to the dimerization,while Cys174 was demonstrated to be involved in the homodimerization.These results provide new insights into the cysteine-related dimerization regulation of sGC.

Changes of Adenylate Cyclase and Guanylate Cyclase in the Frontal Cortex,Lenticula,Corpus Amygdaloideum,and Hippocampus in Morphine‑dependent Rats

To detect the changes of adenylate cyclase(AC)and guanylate cyclase(GC)in the four cerebral regions that are concerned with psychogenic dependence of morphine in rats,including the frontal cortex,lenticula,corpus amygdaloideum,and hippocampus.To discuss the relation between the expressions of AC and GC with the psychogenic dependence on morphine.Different periods of morphine‑dependent rat models were established,and enzyme histochemistry was used to detect the variations of AC and GC in four cerebral regions.Compared with the control group,AC and GC in all the morphine‑dependent groups increased.The data indicated that the amounts of AC and GC were significantly different between the morphine‑dependent groups and the control group when tested at periods of 1 week,2 weeks,4 weeks,and 8 weeks(P<0.05 or P<0.01).There were significant differences when comparing the 1‑week group with the 2‑week,4‑week,and 8‑week groups(P<0.05 or P<0.01).There were significant differences when comparing the 2‑week dependent group with the 4‑week dependent group or the 8‑week dependent group(P<0.05 or P<0.01).The activities of AC and GC increased in four cerebral regions of morphine‑dependent rats.The psychogenic dependence on morphine appears to be closely linked to the upgrade of AC and GC.

Impact of vericiguat on heart failure with reduced ejection fraction:a review

Introduction:Heart failure is a major public health issue with a prevalence of about 26 million people worldwide.Reduced nitric oxide availability,lower soluble guanylate cyclase(sGC)activity,and decreased cyclic guanosine monophosphate(cGMP)production are the causes of HF's development.Vericiguat prescribed under the brand name Verquvo was approved by U.S.Food and Drug Administration(FDA)in January 2021.It is a novel agent and the first sGC stimulator which helps to treat patients suffering from heart failure with reduced ejection fraction(HFrEF).Objective:The mechanism of action(cGMP pathway)of vericiguat,its clinical trials,its use in the treatment of heart failure,and its possible future aspects in therapeutic recommendations are all covered in this review.It will also raise awareness amongst healthcare professionals about the pharmacokinetic and pharmacodynamic parameters,dosing,administration,and drug-related problems of this new drug.Methods:Various databases for drug review were used in this review like PubMed,Medline,Google scholar,Drug bank,U.s.FDA,Medscape,and European society of cardiology guidelines.A total of 58 articles were screened out of which 39 articles were included in this review.Results:This review discusses vericiguat's mechanism of action(cGMP pathway),clinical studies,application in the treatment of heart failure,and potential future considerations in therapeutic recommendations.It will also educate healthcare professionals about the new drug's pharmacokinetics and pharmacodynamics,dose,administration,and drug-related problems.Conclusion:After hospitalization for HFrEF,the 5-year survival rate is just 25%,and disease morbidity and death are stil significant.As adjunctive therapy for individuals with heart failure and a low ejection fraction,vericiguat has a moderate level of effectiveness.Vericiguat's efficacy as an adjunct therapy to different drugs used to cure HF has to be further investigated.Vericiguat's safety and dosage in patients who have severe renal or hepatic illness need to be studied further.

Pharmacological evaluation of NSAID-induced gastropathy as a “Translatable” model of referred visceral sensitivity

AIM To evaluate whether non-steroidal anti-inflammatory drugs(NSAIDs)-induced gastropathy is a clinically predictive model of referred visceral hypersensitivity.METHODS Gastric ulcer pain was induced by the oral administration of indomethacin to male,CD1 mice(n = 10/group) and then assessed by measuring referred abdominal hypersensitivity to tactile application. A diverse range of pharmacological mechanisms contributing to the pain were subsequently investigated. These mechanisms included: transient receptor potential(TRP),sodium and acid-sensing ion channels(ASICs) as well as opioid receptors and guanylate cyclase C(GC-C). RESULTS Results showed that two opioids and a GC-C agonist,morphine,asimadoline and linaclotide,respectively,the TRP antagonists,AMG9810 and HC-030031 and the sodium channel blocker,carbamazepine,elicited a dose-and/or time-dependent attenuation of referred visceral hypersensitivity,while the ASIC blocker,amiloride,was ineffective at all doses tested. CONCLUSION Together,these findings implicate opioid receptors,GC-C,and sodium and TRP channel activation as possible mechanisms associated with visceral hypersensitivity. More importantly,these findings also validate NSAID-induced gastropathy as a sensitive and clinically predictive mouse model suitable for assessing novel molecules with potential pain-attenuating properties.