Nicorandil elevates tissue cGMP levels in a nitric-oxide-independent manner

Effect of Perioperative Nicorandil on Myocardial Protection in Patients Undergoing Cardiac Surgery with Cardiopulmonary Bypass, a Retrospective Study

Background

The potential myocardial protective effect of nicorandil (NICD) in patients undergoing percutaneous coronary intervention has been established. However, its efficacy in the context of cardiac surgery remains controversial. The present study aimed to evaluate the myocardial protective effect of perioperative NICD use in patients undergoing cardiac surgery with cardiopulmonary bypass (CPB).

Methods

We retrospectively gathered data from patients undergoing cardiac bypass surgery between 12/2018 and 04/2021 in Fuwai Hospital. Subsequently, the patients were divided into two groups, NICD group and non-nicorandil (non-NICD) group. A 1, 3 propensity score matching (PSM) was conducted. The primary outcome was the incidence of myocardial injury. The secondary outcomes included the mechanical ventilation (MV) duration, intensive care unit (ICU) length of stay (LOS), hospital LOS, duration of chest drainage, the drainage volume, the total cost, the incidence of acute kidney injury (AKI), and the incidence of acute liver injury (ALI). Subsequently, we divided the entire population into two distinct subgroups based on their administration of NICD, and performed a comprehensive subgroup analysis.

Results

A total of 2406 patients were ultimately included in the study. After PSM, 250 patients in NICD group and 750 patients in non-NICD group were included in the analysis. Perioperative NICD reduced the incidence of myocardial injury (47.2% versus 38.8%, P=0.025). Our subgroup analysis revealed that preoperative NICD administration not only provided myocardial protection benefits (45.7% vs 35.8%, OR 0.66, 95% CI [0.45-0.97], P=0.041), but also demonstrated statistically significant reduction in ALI, the ICU and hospital LOS, and the duration of chest drainage (all P<0.05).

Conclusion

The perioperative NICD administration may confer myocardial protection in patients undergoing cardiac surgery with CPB. Furthermore, the preoperative utilization of NICD has the potential to mitigate the incidence of postoperative ALI, a reduction in the ICU and hospital LOS, and the duration of chest drainage.

Nicorandil and atorvastatin attenuate carbon tetrachloride - induced liver fibrosis in rats

PURPOSE

The present study aimed to evaluate the possible hepatoprotective effects of nicorandil and atorvastatin against experimentally induced liver fibrosis.

MATERIALS AND METHODS

Wistar male rats wereassigned tofivegroups; control group, fibrosis group, the remaining three groups received in addition to CCl₄, N-acetyl cysteine (300 mg/kg), nicorandil(15 mg/kg) and atorvastatin (20 mg/kg), respectively. Liver fibrosis was induced by intraperitoneal injection of rats with CCl₄ (2 ml/kg), twice weekly for five consecutive weeks. All treatments were administered daily starting from the first day of fibrosis induction for five consecutive weeks. By the end of the experiment, fibrosis biomarkers [hepatic transforming growth factor β1 (TGF-β₁) and hydroxyproline (HYP)], liver function [serum alanine transaminase (ALT), aspartate transaminase (AST), albumin and total bilirubin] were assessed. Moreover, lipid profile [total cholesterol, serum triglycerides, high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C)], inflammatory biomarkers [hepatic myeloperoxidase (MPO), serum tumor necrosis factor alpha (TNF-α)], relative liver weight] and oxidative stress biomarkers [malondialdehyde (MDA), glutathione (GSH) and catalase (CAT)] were evaluated. In support, histopathological and immunohistochemical examination of liver alpha smooth muscle actin (α-SMA) were performed.

RESULTS

Nicorandil and atorvastatin effectively reduced fibrosis and liver function biomarkers. They both restored serum lipid profile, TNF-α, MPO, relative liver weight, and hepatic MDA content. Alternatively, they markedly elevated albumin, HDL-C and hepatic content of GSH and CAT. Additionally, a marked histopathological and immunohistochemical improvement of α-SMA was observed.

CONCLUSION

Nicorandil and atorvastatin might be promising protective agents against liver fibrosis through amelioration of liver function, modulation of fibrous formation, anti-inflammatory and antioxidant potentials.

Nicorandil, a KATP Channel Opener, Attenuates Ischemia-Reperfusion Injury in Isolated Rat Lungs

PURPOSE

Nicorandil is a hybrid between nitrates and K_ATP channel opener activators. The aim of this study was to evaluate the nicorandil's effects on ischemia-reperfusion (IR) lung injury and examine the mechanism of its effects.

METHODS

Isolated rat lungs were divided into 6 groups. In the sham group, the lungs were perfused and ventilated for 150 min. In the IR group, after perfusion and ventilation for 30 min, they were interrupted (ischemia) for 60 min, and then resumed for 60 min. In the nicorandil (N) + IR group, nicorandil 6 mg was added before ischemia (nicorandil concentration was 75 µg ml^-1). In the glibenclamide + N + IR group, the L-NAME (N_ω-Nitro-L-arginine methyl ester) + N + IR group and ODQ (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one) + N + IR group, glibenclamide 3 µM, L-NAME 100 µM, and ODQ 30 µM were added 5 min before nicorandil administration, respectively. We measured the coefficient of filtration (Kfc) of the lungs, total pulmonary vascular resistance, and the wet-to-dry lung weight ratio (WW/DW ratio).

RESULTS

Kfc was significantly increased after 60 min reperfusion compared with baseline in the IR group, but no change in the sham group. An increase in Kfc was inhibited in the N + IR group compared with the IR group (0.92 ± 0.28 vs. 2.82 ± 0.68 ml min^-1 mmHg^-1 100 g^-1; P < 0.01). Also, nicorandil attenuated WW/DW ratio was compared with IR group (8.3 ± 0.41 vs. 10.9 ± 2.5; P < 0.05). Nicorandil's inhibitory effect was blocked by glibenclamide and ODQ (P < 0.01), but not by L-NAME.

CONCLUSIONS

Nicorandil attenuated IR injury in isolated rat lungs. This protective effect appears to involve its activation as K_ATP channel opener as well as that of the sGC-cGMP pathway.

Cardiac Na+/Ca2+ exchange stimulators among cardioprotective drugs

We previously reviewed our study of the pharmacological properties of cardiac Na+/Ca2+ exchange (NCX1) inhibitors among cardioprotective drugs, such as amiodarone, bepridil, dronedarone, cibenzoline, azimilide, aprindine, and benzyl-oxyphenyl derivatives (Watanabe et al. in J Pharmacol Sci 102:7-16, 2006). Since then we have continued our studies further and found that some cardioprotective drugs are NCX1 stimulators. Cardiac Na+/Ca2+ exchange current (INCX1) was stimulated by nicorandil (a hybrid ATP-sensitive K+ channel opener), pinacidil (a non-selective ATP-sensitive K+ channel opener), flecainide (an antiarrhythmic drug), and sodium nitroprusside (SNP) (an NO donor). Sildenafil (a phosphodiesterase-5 inhibitor) further increased the pinacidil-induced augmentation of INCX1. In paper, here I review the NCX stimulants that enhance NCX function among the cardioprotective agents we examined such as nicorandil, pinacidil, SNP, sildenafil and flecainide, in addition to atrial natriuretic (ANP) and dofetilide, which were reported by other investigators.

Nicorandil stimulates a Na⁺/Ca²⁺ exchanger by activating guanylate cyclase in guinea pig cardiac myocytes

Nicorandil, a hybrid of an ATP-sensitive K(+) (KATP) channel opener and a nitrate generator, is used clinically for the treatment of angina pectoris. This agent has been reported to exert antiarrhythmic actions by abolishing both triggered activity and spontaneous automaticity in an in vitro study. It is well known that delayed afterdepolarizations (DADs) are caused by the Na(+)/Ca(2+) exchange current (I NCX). In this study, we investigated the effect of nicorandil on the cardiac Na(+)/Ca(2+) exchanger (NCX1). We used the whole-cell patch clamp technique and the Fura-2/AM (Ca(2+) indicator) method to investigate the effect of nicorandil on I NCX in isolated guinea pig ventricular myocytes and CCL39 fibroblast cells transfected with dog heart NCX1. Nicorandil enhanced I NCX in a concentration-dependent manner. The EC50 (half-maximum concentration for enhancement of the drug) values were 15.0 and 8.7 μM for the outward and inward components of I NCX, respectively. 8-Bromoguanosine 3',5'-cyclic monophosphate (8-Br-cGMP), a membrane-permeable analog of guanosine 3',5'-cyclic monophosphate (cGMP), enhanced I NCX. 1H-[1,2,4]Oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), a guanylate cyclase inhibitor (10 μM), completely abolished the nicorandil-induced I NCX increase. Nicorandil increased I NCX in CCL39 cells expressing wild-type NCX1 but did not affect mutant NCX1 without a long intracellular loop between transmembrane segments (TMSs) 5 and 6. Nicorandil at 100 μM abolished DADs induced by electrical stimulation with ouabain. Nicorandil enhanced the function of NCX1 via guanylate cyclase and thus may accelerate Ca(2+) exit via NCX1. This may partially contribute to the cardioprotection by nicorandil in addition to shortening action potential duration (APD) by activating KATP channels.

Nicorandil directly and cyclic GMP-dependently opens K+ channels in human bypass grafts

As we previously demonstrated the role of different K(+) channels in the action of nicorandil on human saphenous vein (HSV) and human internal mammary artery (HIMA), this study aimed to analyse the contribution of the cGMP pathway in nicorandil-induced vasorelaxation and to determine the involvement of cGMP in the K(+) channel-activating effect of nicorandil. An inhibitor of soluble guanylate cyclase (GC), ODQ, significantly inhibited nicorandil-induced relaxation, while ODQ plus glibenclamide, a selective ATP-sensitive K(+) (KATP) channel inhibitor, produced a further inhibition of both vessels. In HSV, ODQ in combination with 4-aminopyridine, a blocker of voltage-gated K(+) (KV) channels, did not modify the concentration-response to nicorandil compared with ODQ, whereas in HIMA, ODQ plus iberiotoxin, a selective blocker of large-conductance Ca(2+)-activated K(+) (BKCa) channels, produced greater inhibition than ODQ alone. We showed that the cGMP pathway plays a significant role in the vasorelaxant effect of nicorandil on HSV and HIMA. It seems that nicorandil directly opens KATP channels in both vessels and BKCa channels in HIMA, although it is possible that stimulation of GC contributes to KATP channels activation in HIMA. Contrary, the activation of KV channels in HSV is probably due to GC activation and increased levels of cGMP.

GATA-4 transcription factor regulates cardiac COX-2 expression induced by nicorandil in left ventricle of rats

BACKGROUND AND AIMS

Cardioprotective effects induced by delayed ischemic preconditioning and by nicorandil are mediated via expression of cardioprotective factors such as COX-2. The present study was undertaken to evaluate whether nicorandil could induce COX-2 in rats and to elucidate its mode of induction pharmacologically.

METHODS AND RESULTS

Three hours after administration of nicorandil (10 mg/kg, p.o.), COX-2 mRNA and protein were significantly increased in the left ventricle, although other cardioprotective factors (Bcl-2, eNOS, hexokinase, HSP, and iNOS) were not increased. This COX-2 induction in the left ventricle was preceded by induction of GATA-4, which was significant from 1 h after administration. Ventricular levels of 6-keto-prostaglandin F1α were increased 6 h after administration. Although pinacidil or isosorbide dinitrate alone did not increase COX-2 mRNA, their combined application significantly increased COX-2 mRNA. Moreover, although glibenclamide or ODQ each partly inhibited the induction of COX-2 mRNA by nicorandil, their combined application significantly inhibited it. These results suggest that nicorandil induces COX-2 protein through both the activation of KATP channels and guanylate cyclase.

CONCLUSION

The present study demonstrated that nicorandil induces COX-2 via GATA-4 induction in the heart through both KATP channel activation and its nitrate-like properties.

A case of vasospastic angina in which the ergonovine provocation test with intracoronary isosorbide dinitrate and nicorandil was effective in the diagnosis of microvascular spasm

A 60-year-old man was admitted with early morning angina while at rest. Coronary angiogram revealed no organic lesions; therefore, a spasm provocation test with ergonovine was performed. Administration of intracoronary ergonovine induced total occlusion of the right coronary artery. The induced total occlusion improved but coronary flow velocity remained severely reduced and chest discomfort with ST-T changes in ECG remained in spite of repeated administration of isosorbide dinitrate (ISDN). Intracoronary administration of nicorandil following ISDN alleviated the chest discomfort, normalized the ST-T change in ECG, and improved the coronary flow. This suggested that microvascular spasm and the epicardial spasm were not relieved by ISDN but by nicorandil. Intracoronary nicorandil injection following ISDN administration may be useful for the diagnosis of microvascular spasm in the ergonovine provocation test.

Involvement of guanylate cyclase and K+ channels in relaxation evoked by ferulate nitrate in rat aorta artery

Vasorelaxant properties of N-2-(ferulamidoethyl)-nitrate (ferulate nitrate, FLNT), a newly synthesized nitrate, were compared with those of isosorbide dinitrate, nicorandil, nitroglycerin, and 8-bromoguanosine 3,5-cyclic monophosphate (8-Br-cGMP) in rat aorta pre-contracted by phenylephrine. FLNT produced vasorelaxation in a concentration-dependent manner (0.1 - 100 µM). The degree of relaxation induced by FLNT was similar to that induced by isosorbide dinitrate. In addition, removal of endothelium did not affect the relaxant effect of FLNT. FLNT caused a rightward shift of the cumulative concentration-response curves of phenylephrine and reduced the maximal efficacy of contraction. 1H-[1,2,4]Oxadiazolo-[4,3-a]quinoxalin-1-one (ODQ, 10 µM) and K(+)-channel blockers charybdotoxin (CHT, 0.1 µM) and BaCl(2) (1 µM) reduced the relaxant effect of FLNT in the endothelium-denuded arteries, whereas glibenclamide (1 µM) and 4-aminopyridine (1 mM) failed to influence FLNT-induced vasorelaxation. Furthermore, in the presence of ODQ, both CHT (0.1 µM) and BaCl(2) (1 µM) still significantly reduced the relaxation evoked by FLNT. Pretreatment of vessels with hydroxocobalamin, a nitric oxide scavenger, abolished the FLNT effect. These findings demonstrate that FLNT induces relaxation of the rat aorta rings endothelium-independently. Furthermore, we demonstrated that FLNT-induced vasorelaxation is related to its stimulation of soluble guanylate cyclase and activation of K(+) channels.

The effect of nicorandil on small intestinal ischemia-reperfusion injury in a canine model

BACKGROUND

It has been shown that nicorandil, which has both ATP-sensitive K+ (KATP) channel opener-like and nitrate-like properties, has an organ-protective effect in ischemia-reperfusion injury in several experimental animal models.

AIMS

We evaluate the effectiveness of nicorandil on warm ischemia-reperfusion injury of the small intestine in a canine model.

METHODS

Eighteen beagle dogs were divided into three groups: the control group (n=6); the nicorandil group (n=6), to which nicorandil was injected intravenously before the ischemia; and the glibenclamide group (n=6), to which glibenclamide, which closes the KATP channel and does not suppress the nitrate effect of nicorandil, was orally administered, and then nicorandil was injected in the same manner as in the nicorandil group. Both the superior mesenteric artery and vein were clamped for 2 h. Superior mesenteric artery blood flow, small intestinal mucosal tissue blood flow, intramucosal pH, and histopathological analyses were compared among the three groups.

RESULTS

Superior mesenteric artery blood flow, mucosal tissue blood flow and pHi after reperfusion were significantly maintained in the nicorandil in comparison with the control and the glibenclamide groups. The histopathological findings showed less severe mucosal damage after reperfusion in the nicorandil group compared with the other two groups. Between the control group and the glibenclamide group, no significant differences were observed in all those parameters.

CONCLUSION

This study suggests that nicorandil has a protective effect on small intestinal IR injury, and activation of KATP channels plays an important role in inhibiting small intestinal IR injury.

KR-31761, a novel K+(ATP)-channel opener, exerts cardioprotective effects by opening both mitochondrial K+(ATP) and Sarcolemmal K+(ATP) channels in rat models of ischemia/reperfusion-induced heart injury

The cardioprotective effects of KR-31761, a newly synthesized K+(ATP) opener, were evaluated in rat models of ischemia/reperfusion (I/R) heart injury. In isolated rat hearts subjected to 30-min global ischemia/30-min reperfusion, KR-31761 perfused prior to ischemia significantly increased both the left ventricular developed pressure (% of predrug LVDP: 17.8, 45.1, 54.2, and 62.6 for the control, 1 microM, 3 microM, and 10 microM, respectively) and double product (DP: heart rate x LVDP; % of predrug DP: 17.5, 44.9, 56.2, and 64.5 for the control, 1 microM, 3 microM, and 10 microM, respectively) at 30-min reperfusion while decreasing the left ventricular end-diastolic pressure (LVEDP). KR-31761 (10 microM) significantly increased the time to contracture during the ischemic period, whereas it concentration-dependently decreased the lactate dehydrogenase release during reperfusion. All these parameters were significantly reversed by 5-hydroxydecanoate (5-HD, 100 microM) and glyburide (1 microM), selective and nonselective blockers of the mitochondrial K+(ATP) (mitoK+(ATP)) channel and K+(ATP) channel, respectively. In anesthetized rats subjected to 30-min occlusion of left anterior descending coronary artery/2.5-h reperfusion, KR-31761 administered 15 min before the onset of ischemia significantly decreased the infarct size (72.2%, 55.1%, and 47.1% for the control, 0.3 mg/kg, i.v., and 1.0 mg/kg, i.v., respectively); and these effects were completely and almost completely abolished by 5-HD (10 mg/kg, i.v.) and HMR-1098, a selective blocker of sarcolemmal K+(ATP) (sarcK+(ATP)) channel (6 mg/kg, i.v.) administered 5 min prior to KR-31761 (72.3% and 67.9%, respectively). KR-31761 only slightly relaxed methoxamine-precontracted rat aorta (IC50: > 30.0 microM). These results suggest that KR-31761 exerts potent cardioprotective effects through the opening of both mitoK+(ATP) and sarcK+(ATP) channels in rat hearts with a minimal vasorelaxant effect.

p38-MAPK is involved in restoration of the lost protection of preconditioning by nicorandil in vivo

Nicorandil, a selective mitochondrial K(ATP) channel opener, reinstates the waned protection after multiple cycles of preconditioning. In this study, we determined the signal transduction activated in heart after 3 or 8 cycles of preconditioning and prolonged ischemia in rabbits treated with placebo or nicorandil. In a first series (eight groups) we evaluated the (%) infarct to risk ratio after 30 min ischemia/3 h reperfusion and in a second series (six groups), we assessed the intracellular levels of cyclic GMP (c-GMP), protein kinase C (PKC) activity and p38-mitogen activated protein kinase (p38-MAPK) phosphorylation from heart samples taken during the long ischemia. Cardioprotection by 3 cycles of preconditioning (11.7+/-3.8% vs 45.9+/-5.2% in the control, P<0.001) was lost after 8 cycles (43.9+/-5.1%, P=NS vs control). Nicorandil restored it to the levels of classic preconditioning (13.7+/-2.4% vs 40.8+/-3.5% in respective controls, P<0.001). This was reversed by the p38-MAPK inhibitor SB203580 (48.8+/-5.1%) which had no protective effect in the control group (44.6+/-5.8%). In the placebo-treated rabbits, intracellular c-GMP and PKC were increased only in the group subjected to 3 cycles of preconditioning. Despite that nicorandil equalizes the intracellular levels of c-GMP, PKC and activated p38-MAPK at the long ischemia, specific alterations of p38-MAPK phosphorylation differentiate the protected groups. Our data delineate the signal transduction mechanism mediating the beneficial effect of nicorandil and imply that the recapture of the lost protection is due to a dynamic process of the intracellular mediators accompanied by an increase in p38-MAPK phosphorylation and not to an instantaneous event.

Prodrugs for the treatment of neglected diseases

Recently, World Health Organization (WHO) and Medicins San Frontieres (MSF) proposed a classification of diseases as global, neglected and extremely neglected. Global diseases, such as cancer, cardiovascular and mental (CNS) diseases represent the targets of the majority of the R&D efforts of pharmaceutical companies. Neglected diseases affect millions of people in the world yet existing drug therapy is limited and often inappropriate. Furthermore, extremely neglected diseases affect people living under miserable conditions who barely have access to the bare necessities for survival. Most of these diseases are excluded from the goals of the R&D programs in the pharmaceutical industry and therefore fall outside the pharmaceutical market. About 14 million people,mainly in developing countries, die each year from infectious diseases. From 1975 to 1999,1393 new drugs were approved yet only 1% were for the treatment of neglected diseases[3]. These numbers have not changed until now, so in those countries there is an urgent need for the design and synthesis of new drugs and in this area the prodrug approach is a very interesting field. It provides, among other effects, activity improvements and toxicity decreases for current and new drugs, improving market availability. It is worth noting that it is essential in drug design to save time and money, and prodrug approaches can be considered of high interest in this respect. The present review covers 20 years of research on the design of prodrugs for the treatment of neglected and extremely neglected diseases such as Chagas' disease (American trypanosomiasis), sleeping sickness (African trypanosomiasis), malaria, sickle cell disease, tuberculosis, leishmaniasis and schistosomiasis.