SIRT1-mediated deacetylation of NF-κB inhibits the MLCK/MLC2 pathway and the expression of ET-1, thus alleviating the development of coronary artery spasm.

Coronary artery spasm (CAS) is an intense vasoconstriction of coronary arteries that causes total or subtotal vessel occlusion. The cardioprotective effect of sirtuin-1 (SIRT1) has been extensively highlighted in coronary artery diseases. The aims within this study include the investigation of the molecular mechanism by which SIRT1 alleviates CAS. SIRT1 expression was first determined by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and Western blot analysis in an endothelin-1 (ET-1)-induced rat CAS model. Interaction among SIRT1, nuclear factor-kappaB (NF-κB), myosin light chain kinase/myosin light chain-2 (MLCK/MLC2), and ET-1 was analyzed using luciferase reporter assay, RT-qPCR, and Western blot analysis. After ectopic expression and depletion experiments in vascular smooth muscle cells (VSMCs), contraction and proliferation of VSMCs and expression of contraction-related proteins (α-SMA, calponin, and SM22α) were measured by collagen gel contraction, 5-ethynyl-2'-deoxyuridine (EdU) assay, RT-qPCR, and Western blot analysis. The obtained results showed that SIRT1 expression was reduced in rat CAS models. However, overexpression of SIRT1 inhibited the contraction and proliferation of VSMCs in vitro. Mechanistic investigation indicated that SIRT1 inhibited NF-κB expression through deacetylation. Moreover, NF-κB could activate the MLCK/MLC2 pathway and upregulate ET-1 expression by binding to their promoter regions, thus inducing VSMC contraction and proliferation in vitro. In vivo experimental results also revealed that SIRT1 alleviated CAS through regulation of the NF-κB/MLCK/MLC2/ET-1 signaling axis. Collectively, our data suggested that SIRT1 could mediate the deacetylation of NF-κB, disrupt the MLCK/MLC2 pathway, and inhibit the expression of ET-1 to relieve CAS, providing a theoretical basis for the prospect of CAS treatment and prevention.NEW & NOTEWORTHY Rat coronary artery spasm models exhibit reduced expression of SIRT1. Overexpression of SIRT1 inhibits contraction and proliferation of VSMCs. SIRT1 inhibits NF-κB through deacetylation to modulate VSMC contraction and proliferation. NF-κB activates the MLCK/MLC2 pathway. NF-κB upregulates ET-1 to modulate VSMC contraction and proliferation.

Increased plasma xanthine oxidoreductase activity deteriorates coronary artery spasm.

Increased reactive oxygen species (ROS) contributes to the development of endothelial dysfunction, which is involved in coronary artery spasm (CAS). Xanthine oxidoreductase (XOR) plays a pivotal role in producing both uric acid and ROS. However, the association between plasma XOR activity and CAS has not been elucidated. The aim of this study was to investigate whether plasma XOR activity is associated with CAS. We measured XOR activity in 104 patients suspected for CAS, who presented without significant coronary artery stenosis and underwent intracoronary acetylcholine provocation tests. CAS was provoked in 44 patients and they had significantly higher XOR activity as compared with those without CAS. The patients were divided into three groups based on the XOR activity. The prevalence rate of CAS was increased with increasing XOR activity. A multivariate logistic regression analysis showed that the 3rd tertile group exhibited a higher incidence of CAS as compared with the 1st tertile group [odds ratio (OR) 6.9, P = 0.001) and the 2nd tertile group (OR 3.2, P = 0.033) after adjustment for conventional CAS risk factors, respectively. The C index was significantly improved by the addition of XOR activity to the baseline model based on CAS risk factors. Furthermore, the 3rd tertile group had the highest incidence of severe spasm defined as total obstruction, flow-limiting stenosis, diffuse spasm, multivessel spasm, and/or lethal arrhythmia. This is a first report to elucidate the association of plasma XOR activity with CAS. Increased plasma XOR activity is significantly associated with CAS.

Enhanced transient receptor potential channel-mediated Ca2+ influx in the cells with phospholipase C-δ1 overexpression: its possible role in coronary artery spasm.

We reported that coronary spasm was induced in the transgenic mice with the increased phospholipase C (PLC)-δ1 activity. We investigated the effect of enhanced PLC-δ1 on Ca2+ influx and its underlying mechanisms. We used human embryonic kidney (HEK)-293 and coronary arteries smooth muscle cells (CASMC). Intracellular free Ca2+ concentration ([Ca2+ ]i ; nm) was measured by fura-2, and Ca2+ influx was evaluated by the increase in [Ca2+ ]i after addition of extracellular Ca2+ . Acetylcholine (ACh) was used to induce Ca2+ influx. ACh-induced peak Ca2+ influx was 19 ± 3 in control HEK-293 cells and 71 ± 8 in the cells with PLC-δ1 overexpression (P < 0.05 between two groups). Nifedipine partially suppressed this Ca2+ influx, whereas either 2-APB or knockdown of classical transient receptor potential channel 6 (TRPC6) blocked this Ca2+ influx. In the human CASMC, ACh-induced peak Ca2+ influx was 29 ± 6 in the control and was increased to 45 ± 16 by PLC-δ1 overexpression (P < 0.05). Like HEK-293 cells, pretreatment with nifedipine partially suppressed Ca2+ influx, whereas either 2-APB or knockdown of TRPC6 blocked it. ACh-induced Ca2+ influx was enhanced by PLC-δ1 overexpression, and was blocked partially by nifedipine and completely by 2-APB. TRPC-mediated Ca2+ influx may be related to the enhanced Ca2+ influx in PLC-δ1 overexpression.

Variant Aldehyde Dehydrogenase 2 (ALDH2*2) in East Asians Interactively Exacerbates Tobacco Smoking Risk for Coronary Spasm　- Possible Role of Reactive Aldehydes.

BACKGROUND: Coronary spastic angina (CSA) is common among East Asians and tobacco smoking (TS) is an established risk factor for CSA. Aldehyde dehydrogenase 2 (ALDH2) plays a key role in removing reactive toxic aldehydes and a deficient variant ALDH2 genotype (ALDH2*2) is prevalent among East Asians. We examined the interaction between TS andALDH2*2as a risk factor for CSA to better understand the disease pathogenesis.Methods and Results:The study subjects comprised 410 patients (258 men, 152 women; mean age, 66.3±11.5) in whom intracoronary injection of acetylcholine was performed on suspicion of CSA.ALDH2genotyping was performed by direct application of the Taqman polymerase chain reaction system. Of the study subjects, 244 had CSA proven and 166 were non-CSA. The frequencies of male sex,ALDH2*2, alcohol flushing syndrome, TS, coronary organic stenosis, and plasma levels of uric acid were higher (P<0.001, P<0.001, P<0.001, P<0.001, P<0.001, and P=0.015, respectively) and that of high-density lipoprotein cholesterol lower (P=0.002) in the CSA than non-CSA group. Multivariable logistic regression analysis revealed thatALDH2*2and TS were significant risk factors for CSA (P<0.001 and P=0.002, respectively).ALDH2*2exacerbated TS risk for CSA more than the multiplicative effects of each. CONCLUSIONS: ALDH2*2synergistically exacerbates TS risk for CSA, probably through aldehydes.

Role Of MMP-2 and MMP-9 in Resistance to Drug Therapy in Patients with Resistant Hypertension / Papel da MMP-2 e MMP-9 na Resistência à Terapia Medicamentosa em Pacientes com Hipertensão Arterial Resistente

AbstractBackground:Despite the increased evidence of the important role of matrix metalloproteinases (MMP-9 and MMP‑2) in the pathophysiology of hypertension, the profile of these molecules in resistant hypertension (RHTN) remains unknown.Objectives:To compare the plasma levels of MMP-9 and MMP-2 and of their tissue inhibitors (TIMP-1 and TIMP-2, respectively), as well as their MMP-9/TIMP-1 and MMP-2/TIMP-2 ratios, between patients with controlled RHTN (CRHTN, n=41) and uncontrolled RHTN (UCRHTN, n=35). In addition, the association of those parameters with clinical characteristics, office blood pressure (BP) and arterial stiffness (determined by pulse wave velocity) was evaluate in those subgroups.Methods:This study included 76 individuals diagnosed with RHTN and submitted to physical examination, electrocardiogram, and laboratory tests to assess biochemical parameters.Results:Similar values of MMP-9, MMP-2, TIMP-1, TIMP-2, and MMP-9/TIMP-1 and MMP-2/TIMP-2 ratios were found in the UCRHTN and CRHTN subgroups (P>0.05). A significant correlation was found between diastolic BP (DBP) and MMP-9/TIMP-1 ratio (r=0.37; P=0.02) and DPB and MMP-2 (r=-0.40; P=0.02) in the UCRHTN subgroup. On the other hand, no correlation was observed in the CRHTN subgroup. Logistic regression models demonstrated that MMP-9, MMP-2, TIMP-1, TIMP-2 and their ratios were not associated with the lack of BP control.Conclusion:These findings suggest that neither MMP-2 nor MMP-9 affect BP control in RHTN subjects.

ResumoFundamento:A despeito da crescente evidência do importante papel das metaloproteinases da matriz extracelular (MMP-9 e MMP-2) na fisiopatologia da hipertensão, o perfil dessas moléculas na hipertensão arterial resistente (HAR) permanece desconhecido.Objetivo:Comparar os níveis plasmáticos de MMP-9 e MMP-2 e seus inibidores teciduais (TIMP-1 e TIMP-2, respectivamente), assim como as suas razões MMP-9/TIMP-1 e MMP-2/TIMP-2, entre pacientes com HAR controlada (HARC, n = 41) e HAR não controlada (HARNC, n = 35). Além disso, a associação desses parâmetros com as características clínicas, pressão arterial (PA) de consultório e rigidez arterial (determinada pela velocidade da onda de pulso) foi avaliada nesses subgrupos.Métodos:Este estudo incluiu 76 indivíduos com HAR submetidos a exame físico, eletrocardiografia e exames laboratoriais para a avaliação de parâmetros bioquímicos.Resultados:Valores semelhantes de MMP-9, MMP-2, TIMP-1, TIMP-2, e razões MMP-9/TIMP-1 e MMP-2/TIMP-2 foram encontrados nos subgrupos HARNC e HARC (p > 0,05). Observou-se uma correlação significativa entre PA diastólica (PAD) e razão MMP-9/TIMP-1 (r = 0,37; p = 0,02) e PAD e MMP-2 (r = -0,40; p = 0,02) no subgrupo HARNC. Por outro lado, não se observou correlação no subgrupo HARC. Os modelos de regressão logística demonstraram que MMP-9, MMP-2, TIMP-1, TIMP-2 e suas razões não se associaram com a falta de controle da PA.Conclusão:Esses achados sugerem que MMP-2 e MMP-9 não afetem o controle da PA em indivíduos com HAR.

Role of MMP-2 and MMP-9 in resistance to drug therapy in patients with resistant hypertension.

BACKGROUND: Despite the increased evidence of the important role of matrix metalloproteinases (MMP-9 and MMP­2) in the pathophysiology of hypertension, the profile of these molecules in resistant hypertension (RHTN) remains unknown. OBJECTIVES: To compare the plasma levels of MMP-9 and MMP-2 and of their tissue inhibitors (TIMP-1 and TIMP-2, respectively), as well as their MMP-9/TIMP-1 and MMP-2/TIMP-2 ratios, between patients with controlled RHTN (CRHTN, n=41) and uncontrolled RHTN (UCRHTN, n=35). In addition, the association of those parameters with clinical characteristics, office blood pressure (BP) and arterial stiffness (determined by pulse wave velocity) was evaluate in those subgroups. METHODS: This study included 76 individuals diagnosed with RHTN and submitted to physical examination, electrocardiogram, and laboratory tests to assess biochemical parameters. RESULTS: Similar values of MMP-9, MMP-2, TIMP-1, TIMP-2, and MMP-9/TIMP-1 and MMP-2/TIMP-2 ratios were found in the UCRHTN and CRHTN subgroups (P>0.05). A significant correlation was found between diastolic BP (DBP) and MMP-9/TIMP-1 ratio (r=0.37; P=0.02) and DPB and MMP-2 (r=-0.40; P=0.02) in the UCRHTN subgroup. On the other hand, no correlation was observed in the CRHTN subgroup. Logistic regression models demonstrated that MMP-9, MMP-2, TIMP-1, TIMP-2 and their ratios were not associated with the lack of BP control. CONCLUSION: These findings suggest that neither MMP-2 nor MMP-9 affect BP control in RHTN subjects.

Association of Adventitial Vasa Vasorum and Inflammation With Coronary Hyperconstriction After Drug-Eluting Stent Implantation in Pigs In Vivo.

BACKGROUND: The importance of adventitial inflammation has been implicated for the pathogenesis of coronary artery disease. However, the roles of adventitial changes in drug-eluting stent (DES)-induced coronary hyperconstriction remain largely unknown. In the present study, this issue in pigs in vivo with a special reference to adventitial vasa vasorum (VV) formation and Rho-kinase activation, a central mechanism of coronary vasospasm, was examined. METHODS AND RESULTS: Each animal received a sirolimus-eluting stent (SES) and a biolimus A9-eluting stent (BES), one in the left anterior descending and another in the left circumflex coronary arteries in a randomized manner (n=18). After 1, 3 and 6 months, coronary vasomotion was examined. At 1 month, coronary vasoconstriction to serotonin was significantly enhanced at the SES edges as compared with the BES edges (SES, 52±7% vs. BES, 22±3%, P<0.01), which was equally prevented by a selective Rho-kinase inhibitor, hydroxyfasudil. A significant difference in vasoconstriction between SES and BES was sustained for 6 months. A micro-CT showed VV augmentation at the SES site, extending to the proximal and distal edges. Immunostainings demonstrated that VV formation, macrophage infiltration in the adventitia and Rho-kinase expressions/activation were significantly enhanced at the SES edges as compared with the BES edges. CONCLUSIONS: The DES with durable polymers enhances VV formation and inflammation in the adventitia, associating with the pathogenesis of DES-induced coronary hyperconstriction through Rho-kinase activation in pigs in vivo.

East asian variant of aldehyde dehydrogenase 2 is associated with coronary spastic angina: possible roles of reactive aldehydes and implications of alcohol flushing syndrome.

BACKGROUND: Coronary spastic angina (CSA) is a common disease among East Asians, including Japanese. The prevalence of alcohol flushing syndrome associated with deficient activity of the variant aldehyde dehydrogenase 2 (ALDH2*2) genotype is prevalent among East Asians. We examined whether CSA is associated with the ALDH2*2 genotype in Japanese. METHODS AND RESULTS: The study subjects consisted of 202 patients in whom intracoronary injection of acetylcholine was performed by angiography on suspicion of CSA (119 men and 83 women; mean age, 66.2±11.4 years). They were divided into CSA (112 patients) and control groups (90 patients). ALDH2 genotyping was performed by the direct application of the TaqMan polymerase chain reaction system on dried whole blood. Clinical and laboratory data were examined using conventional methods. The frequencies of male sex, ALDH2*2 genotype carriers, alcohol flushing syndrome, tobacco smoking, and the plasma level of uric acid were higher (P<0.001, P<0.001, P<0.001, P<0.001, and P=0.007, respectively) and the plasma high-density lipoprotein cholesterol levels were lower (P<0.001) in the CSA group than in the control group. The multivariable logistic regression analysis revealed that ALDH2*2 genotype and smoking were significantly associated with CSA (P<0.001 and P=0.024, respectively). CONCLUSIONS: East Asian variant ALDH2*2 genotypes and, hence, deficient ALDH2 activity were associated with CSA in Japanese. These data support further investigation of treatment targeting aldehydes for CSA.

Alcohol flushing and positive ethanol patch test in patients with coronary spastic angina: possible role of aldehyde dehydrogenase 2 polymorphisms.

OBJECTIVE: Coronary spasm plays an important role in the pathogenesis of coronary heart disease (CHD) and angina pectoris caused by coronary spasm or coronary spastic angina (CSA) is prevalent in Japan. However, the precise mechanisms underlying coronary spasm are unclear. Alcohol intolerance is prevalent among East Asians, and we previously reported that coronary spasm could be induced by alcohol intake in CSA patients. We herein examined whether CSA is associated with alcohol intolerance in Japanese subjects. METHODS: The study subjects consisted of 80 CSA patients (57 men/ 23 women, mean age 62 ± 12) and 52 non-CSA patients (25 men/27 women, mean age 63 ± 10). The ethanol patch test (EPT) and questionnaire which evaluates flushing after ethanol intake, along with an examination of clinical features and laboratory chemistry data for CHD risk factors were done. Gender (male) and smoking were higher (p=0.007, and p=0.019, respectively) and plasma HDL cholesterol level was lower (p=0.035) in the CSA patients than in the non-CSA patients. Multivariable logistic regression analysis including age, EPT, smoking, and plasma HDL cholesterol level as independent variables revealed that positive EPT and smoking were significant predictors of CSA (p=0.011 and p=0.016, respectively). CONCLUSION: Positive EPT and alcohol flushing following alcohol intake, as well as smoking and plasma levels of HDL cholesterol, were significantly associated with CSA in Japanese patients. Therefore, alcohol ingestion as well as smoking is a significant risk factor for CSA in Japanese.

Enhanced Rho-kinase activity in patients with vasospastic angina after the Great East Japan Earthquake.

BACKGROUND: It remains unclear whether disease activity of vasospastic angina (VSA) is altered during a disaster. METHODS AND RESULTS: Before and after the Great East Japan Earthquake, we examined Rho-kinase activity in circulating neutrophils of 11 VSA patients and their mental stress with the post-traumatic stress disorder (PTSD) questionnaire. Rho-kinase activity was significantly increased at 6 months after the Earthquake, and was returned to baseline level at 12 months. Importantly, percent change in Rho-kinase activity was significantly correlated with the PTSD score. CONCLUSIONS: These results indicate that the Rho-kinase activity of VSA patients was transiently enhanced associated with disaster-related mental stress.

Increased leukocyte Rho-associated coiled-coil containing protein kinase activity predicts the presence and severity of coronary vasospastic angina.

OBJECTIVE: Although inhibition of Rho-associated coiled-coil containing protein kinase (ROCK) has been shown to prevent coronary vasospastic angina (CVA), direct evidence linking ROCK activity and CVA is lacking. Accordingly, we investigated whether ROCK activity is an independent marker for CVA and is altered after treatment with antispastic medications. METHODS AND RESULTS: We prospectively studied 31 Taiwanese patients who were diagnosed with CVA and 33 control subjects. Subject demographics were recorded, and blood samples were obtained at baseline in all participants and in CVA patients after 3 months of antispastic treatment. Compared with control subjects, leukocyte ROCK activity was greater in CVA patients (136% versus 91%, P<0.001). A cutoff value for leukocyte ROCK activity of 104% predicted the presence of CVA with specificity and sensitivity rates of 88% and 84%, respectively. ROCK activity increased with the severity of CVA (P for trend<0.001). Following 3-month treatment of antispastic agents, leukocyte ROCK activity, high-sensitivity C-reactive protein, and interleukin-6 levels were reduced by 43%, 42% and 27%, respectively (P<0.05 for all). CONCLUSIONS: Increased levels of leukocyte ROCK activity independently predicted the presence of CVA and correlated with CVA severity. Treatment with antispastic agents substantially reduced the level of leukocyte ROCK activity.

Coronary vasospasm induced in transgenic mouse with increased phospholipase C-δ1 activity.

BACKGROUND: We reported that phospholipase C (PLC)-δ1 activity was enhanced 3-fold in patients with coronary spastic angina. We detected variant PLC-δ1 with replacement of arginine 257 by histidine (R257H) showing increased enzymatic activity. We tested the hypothesis that increased PLC-δ1 activity causes enhanced coronary vasomotility. METHODS AND RESULTS: We generated transgenic (TG) mice with human R257H variant PLC-δ1 in vascular smooth muscle cells. PLC enzymatic activity in the coronary artery was increased by 2.57 and 1.89 times, respectively, in homozygous and heterozygous TG compared with wild-type (WT) mice. ST elevation after ergometrine occurred in 17 of 18 homozygous TG, 6 of 20 heterozygous TG, and 3 of 22 WT mice (P<0.01, homozygous TG versus WT; P<0.05, homozygous TG versus heterozygous TG; P=NS, heterozygous TG versus WT). ST elevation was associated with bradyarrhythmias in homozygous TG mice. Focal coronary artery narrowing was documented with the microvascular filling technique in 3 of 5 homozygous TG mice after ergometrine but not in any of 7 WT mice (P<0.05). In the isolated Langendorff hearts, coronary perfusion pressure was increased after ergometrine in homozygous TG mice (P<0.01) but not in heterozygous TG or WT mice. Coronary perfusion pressure increase after prostaglandin F2α was similar among homozygous TG, heterozygous TG, and WT mice. Cultured rat aortic smooth muscle cells transfected with variant PLC-δ1 showed a higher PLC activity than those with WT PLC-δ1 (P<0.05) and furthermore showed greater intracellular Ca2+ response to acetylcholine in variant than in WT PLC-δ1 (P<0.05). CONCLUSIONS: Increased PLC-δ1 activity enhances coronary vasomotility such as that seen in patients with coronary spastic angina.

Lipocalin-type prostaglandin D synthase is associated with coronary vasospasm and vasomotor reactivity in response to acetylcholine.

BACKGROUND: Lipocalin-type prostaglandin D synthase (L-PGDS) catalyzes the biosynthesis of PGD(2), which acts as an anticoagulant, vasodilator, and inflammatory mediator. We examined the serum L-PGDS level, coronary macro- and microvasomotor functions, and their relationship in patients with chest pain and angiographically normal coronary arteries. METHODS AND RESULTS: The study included 96 patients who underwent diagnostic coronary angiography and had angiographically normal coronary arteries. Blood flow of the left anterior descending coronary artery (LAD) was analyzed by Doppler guidewire examination. Serum L-PGDS level was determined by ELISA. Infusion of acetylcholine (ACh) induced vasospasm of the LAD in all patients with vasospastic angina (VSA) (n=45), but in none of the patients without VSA (n=51). There were no significant differences in the baseline clinical characteristics of the nonVSA and VSA groups, except for the frequency of smoking. Serum L-PGDS level in the VSA group was significantly higher than that in the nonVSA group (77.1±4.4 vs. 63.9±2.5 µg/dl, P<0.01). Significant negative correlations were observed between the degree of LAD vasomotion in response to ACh and serum L-PGDS level (3 µg/min: r=-0.33; 10 µg/min: r=-0.35; 30 µg/min: r=-0.33, P<0.01). CONCLUSIONS: The L-PGDS level was elevated in patients with VSA and was associated with epicardial coronary vasomotion in response to ACh.

Myocardial ischemia: current concepts and future perspectives.

Ischemic heart disease is the leading cause of morbidity and mortality in a worldwide epidemic. Myocardial ischemia is characterized by an imbalance between myocardial oxygen supply and demand, causing cardiac dysfunction, arrhythmias, myocardial infarction, and sudden death. Various clinical ischemic manifestations are caused by obstruction of coronary blood flow by coronary plaques, thrombosis, and/or hyperconstriction/vasospasm of epicardial and microvascular coronary arteries, in which gender difference also is involved due in part to estrogen hormonal state. The coronary circulation matches blood flow with oxygen requirements by coordinating the resistances within microvasculature, where the endothelium plays an important role by liberating several vasodilator substances. The impaired endothelial regulation is involved in the pathogenesis of a wide variety of cardiovascular diseases and therefore is an important therapeutic target. Activation of Rho-kinase pathway is involved in the pathogenesis of both endothelial dysfunction and vascular smooth muscle hypercontraction and also should be an important therapeutic target.

The endothelial nitric oxide synthase gene -786T/C polymorphism is a predictive factor for reattacks of coronary spasm.

OBJECTIVE: We previously found a -786T/C polymorphism in the 5'-flanking region of the endothelial nitric oxide synthase (eNOS) gene and reported that this polymorphism is strongly associated with coronary spasm. In this study, we examined whether the polymorphism is a prognostic marker in coronary spasm patients. METHODS AND RESULTS: We examined the clinical courses of 201 consecutive patients with coronary spasm who were admitted to our institution: 146 patients with the -786T/T genotype; 50 patients with the -786C/T genotype; and five patients with the -786C/C genotype. The mean follow-up period was 76+/-60 months. All the patients took calcium channel blockers and/or nitrate during the follow-up period. In this study, no patients died due to a cardiac event. About 25 patients were readmitted owing to cardiovascular disease. Out of these 25 patients, 23 patients were readmitted owing to a reattack of coronary spasm. The -786C allele was significantly associated with readmission due to coronary spasm (P=0.0072, odds ratio: 3.37 in the dominant effect). Kaplan-Meier analysis revealed that the occurrence of readmission was significantly higher in the patients with the -786C allele than in the patients without the -786C allele (P=0.0079). Further, multiple logistic regression analysis revealed that the -786T/C polymorphism was an independent predictor for readmission due to reattack of coronary spasm (P=0.006; relative risk=3.590). CONCLUSIONS: The eNOS -786C allele is an independent risk factor for readmission due to a recurrent attack of coronary spasm in patients with coronary spasm, even if the patients have taken calcium channel blockers and/or nitrate.

Endothelin-1 promotes Ca2+ antagonist-insensitive coronary smooth muscle contraction via activation of epsilon-protein kinase C.

Certain forms of coronary artery disease do not respond to treatment with Ca2+ channel blockers, and a role for endothelin-1 (ET-1) in Ca2+ antagonist-insensitive forms of coronary vasospasm has been suggested; however, the signaling mechanisms involved are unclear. We tested the hypothesis that a component of ET-1-induced coronary smooth muscle contraction is Ca2+ antagonist-insensitive and involves activation of protein kinase C (PKC). Cell contraction was measured in smooth muscle cells isolated from porcine coronary artery, [Ca2+]i was measured in fura-2 loaded cells, and the cytosolic and particulate fractions were examined for PKC activity and reactivity with isoform-specific PKC antibodies using Western blot analysis. In Hank's solution (1 mmol/L Ca2+), ET-1 (10(-7) mol/L) caused a transient increase in [Ca2+]i (236+/-14 nmol/L) followed by a maintained increase in [Ca2+]i (184+/-8 nmol/L) and 35% cell contraction. The Ca2+ channel blockers verapamil and diltiazem (10(-6) mol/L) abolished the maintained ET-1-induced [Ca2+]i, but only partially inhibited ET-1-induced cell contraction to 18%. The verapamil-insensitive component of ET-1 contraction was inhibited by the PKC inhibitors calphostin C and epsilon-PKCV1-2. ET-1 caused translocation of Ca2+-dependent alpha-PKC and Ca2+-independent epsilon-PKC from the cytosolic to the particulate fraction that was inhibited by calphostin C. Verapamil abolished ET-1-induced translocation of alpha-PKC, but not that of epsilon-PKC. Phorbol 12-myristate 13-acetate (10(-6) mol/L), a direct activator of PKC, caused 22% cell contraction, with no increase in [Ca2+]i, and translocation of epsilon-PKC that was inhibited by calphostin C, but not by verapamil. KCl (51 mmol/L), which stimulates Ca2+ influx, caused 35% cell contraction and increase in [Ca2+]i (291+/-11 nmol/L) that were inhibited by verapamil, but not by calphostin C, and did not cause translocation of alpha- or epsilon-PKC. In Ca2+-free (2 mmol/L EGTA) Hank's solution, ET-1 caused 15% cell contraction, with no increase in [Ca2+]i, and translocation of epsilon-PKC that were inhibited by epsilon-PKC V1-2 inhibitory peptide. Thus, a significant component of ET-1-induced contraction of coronary smooth muscle is Ca2+ antagonist-insensitive and involves activation and translocation of Ca2+-independent epsilon-PKC, and may represent a signaling mechanism of Ca2+ antagonist-resistant forms of coronary vasospasm.

Evidence for protein kinase C-mediated activation of Rho-kinase in a porcine model of coronary artery spasm.

OBJECTIVE: We have recently demonstrated that protein kinase C (PKC) and Rho-kinase play important roles in coronary vasospasm in a porcine model. However, it remains to be examined whether there is an interaction between the two molecules to cause the spasm. METHODS AND RESULTS: A segment of left porcine coronary artery was chronically treated with IL-1beta-bound microbeads in vivo. Two weeks after the operation, phorbol ester caused coronary spasm in vivo and coronary hypercontractions in vitro at the IL-1beta-treated segment; both were significantly inhibited by hydroxyfasudil, a specific Rho-kinase inhibitor. Guanosine 5'-[gamma-thio]triphosphate (GTPgammaS), which activates Rho with a resultant activation of Rho-kinase, enhanced Ca2+ sensitization of permeabilized vascular smooth muscle cells, which were resistant to the blockade of PKC by calphostin C. The GTPgammaS-induced Ca2+ sensitization was greater in the spastic segment than in the control segment. Western blot analysis revealed that only PKCdelta isoform was activated during the hypercontraction. CONCLUSIONS: These results demonstrate that PKC and Rho-kinase coexist on the same intracellular signaling pathway, with PKC located upstream on Rho-kinase, and that among the PKC isoforms, only PKCdelta may be involved. Thus, the strategy to inhibit Rho-kinase rather than PKC may be a more specific and useful treatment for coronary spasm.