STRESS signaling pathways that modulate cardiac myocyte apoptosis

The heart is a dynamic organ capable of significant architectural remodeling, cellular adaptations, and molecular reprogramming following both physiologic and pathologic stimulation. These whole organ and cellular adaptations are typically initiated by stress-responsive signaling pathways, which serve as central transducers of cardiac hypertrophic growth and/or ventricular dilation. In addition to initiating and maintaining phenotypic alterations in cardiac structure and function, stress-responsive signaling pathways have also been implicated in affecting the decision of myocytes to either survive or undergo programmed cell death (apoptosis). Indeed, necrosis or apoptosis of individual myocytes has become appreciated as yet another maladaptive event that negatively impacts the myocardium and its propensity towards failure. Here we will discuss the known associations between select stress-induced and neuroendocrine-mediated signaling pathways and regulation of cardiac myocyte survival or cell death. These signaling pathways include the extracellular signal-regulated protein kinases (ERK), p38 mitogen-activated protein kinases (MAPK), c-Jun NH2-terminal kinases (JNK), protein kinase C (PKC) isoforms, the protein phosphatase calcineurin, as well as a select group of additional kinases such as Janus kinase (JAK). While a fair amount of discordance exists in the literature, we will weigh evidence that largely suggests a pro-apoptotic regulatory role for the p38 mitogen-activated protein kinase, JNK, and PKCdelta, yet an anti-apoptotic regulatory role for ERK, PKCepsilon, JAK, and calcineurin in the myocardium.     

Calcitriol modulation of cardiac contractile performance via protein kinase C

Vitamin D(3) deficiency enhances cardiac contraction in experimental studies, yet paradoxically this deficiency is linked to congestive heart failure in humans. Activated vitamin D(3) (1alpha,25-dihydroxyvitamin D(3)) or calcitriol, decreases peak force and activates protein kinase C (PKC) in isolated perfused hearts. However, the direct influence of this hormone on adult cardiac myocyte contractile function is not well understood. Our aim is to investigate whether 1alpha,25-dihydroxyvitamin D(3) acutely modulates contractile function via PKC activation in adult rat cardiac myocytes. Sarcomere shortening and re-lengthening were measured in electrically stimulated myocytes isolated from adult rat hearts, and the vitamin D(3) response (10(-10) to 10(-7) M) was compared to shortening observed under basal conditions. Maximum changes in sarcomere shortening and relaxation were observed with 10(-9) M 1alpha,25-dihydroxyvitamin D(3). This dose decreased peak shortening, and accelerated contraction and relaxation rates within 5 min of administration, and changes in the Ca(2+) transient contributed to the peak shortening and relaxation effects. The PKC inhibitor, bis-indolylmaleimide (500 nM) largely blocked the acute influence of the most potent dose (10(-9) M) on contractile function. While peak shortening and shortening rate returned to baseline within 30 min, there was a sustained acceleration of relaxation that continued over 60 min. Phosphorylation of the Ca(2+) regulatory proteins, phospholamban, and cardiac troponin I correlated with the accelerated relaxation observed in response to acute application of 1alpha,25-dihydroxyvitamin D(3). Accelerated relaxation continued to be observed after chronic addition of 1alpha,25-dihydroxyvitamin D(3) (e.g. 2 days), yet this sustained increase in relaxation was not associated with increased phosphorylation of phospholamban or troponin I. These results provide evidence that 1alpha,25-dihydroxyvitamin D(3) directly modulates adult myocyte contractile function, and protein kinase C plays an important signaling role in the acute response. Phosphorylation of key Ca(2+) regulatory proteins by this kinase contributes to the enhanced relaxation observed in response to acute, but not chronic calcitriol.     

阿托伐他汀在心肌细胞肥大治疗中的作用

大量研究表明阿托伐他汀可干预心室重塑的形成和发展.应用阿托伐他汀能从不同途径发挥独特的心血管保护效应.本文从心肌细胞肥大这个角度阐述阿托伐他汀对心室重塑的影响.     

Pharmacological implications from the adhesion-induced signaling profiles in cultured human retinal pigment epithelial cells

Extracellular matrix (ECM) plays an active and complex role in regulating cellular behaviors, including proliferation and adhesion. This study aimed at delineating the adhesion-induced signaling profiles in cultured human retinal pigment epithelium (RPE) cells and investigating the antiadhesion effect of antiproliferative drugs in this context. RPE R-50 cells grown on various ECM molecules, such as type I and IV collagens, fibronectin, and laminin, were used for adhesion assay and for examining the phosphorylation profiles of signaling mediators including Akt, extracellular signal-regulated kinase (ERK) 1/2, and integrin-linked kinase (ILK) using Western blotting. The cells receiving antiproliferative drug treatment at subtoxic doses were used to evaluate their antiadhesive and suppressive effects on kinase activities. ECM coating enhanced adhesion and spreading of RPE cells significantly. The cellular attachment onto ECM-coated surfaces differentially induced Akt, ERK1/2, and ILK phosphorylation, and concomitantly increased p53 phosphorylation and cyclin D1 expression, but decreased Bcl-2/Bax ratios. Treatment with antiproliferative agents, including 5-fluorouracil, mitomycin C, and daunomycin, at subtoxic doses suppressed the ability of RPE cells to adhere to ECM substratum significantly. This suppression was in part mediated through reduction of integrin β1 and β3 expressions and interfering Akt-ILK signaling activity. Mechanistically, blockade of PI3K/Akt signaling resulted in the suppressed adhesion of RPE cells to ECM. These findings support the hypothesis that, in addition to their antimitogenic effect, antiproliferative agents also exhibit suppressive effect on the adhesiveness of cultured RPE cells. Moreover, inhibitors of the PI3K/Akt signaling mediator can potentially be used as therapeutic agents for proliferative vitreoretinopathy.     

血管紧张素-(1-7)在拮抗血管紧张素Ⅱ诱导心肌细胞Cx43间隙连接上调中的作用

目的探讨血管紧张素-(1-7)[Ang-(1-7)]在血管紧张素Ⅱ(AngⅡ)诱导心肌细胞Cx43间隙连接中作用。方法AngⅡ处理培养心肌细胞24h。PD98059和Ang-(1-7)在AngⅡ刺激细胞前1h加到培养基中,对照组加等体积药物溶剂DMSO。用Western blot分析和电镜观察心肌细胞Cx43表达和间隙连接。结果Western blot分析显示用10-9~10-6mol/L AngⅡ刺激细胞24h,Cx43的表达与对照组相比呈浓度依赖性增加;用AngⅡ0.1μmol/L刺激心肌细胞24h,与对照组相比Cx43表达上调、磷酸化ERK1/2活性增加(P<0.01),ERK1/2激酶特异性抑制剂1μmol/LPD98059和0.1μmol/L Ang-(1-7)能阻断AngⅡ上调Cx43表达和磷酸化ERK1/2活性增加。电镜观察证明用AngⅡ0.1μmol/L刺激心肌细胞24h,AngⅡ处理组细胞间隙连接数目和大小较对照组增加(P<0.05),0.1μmol/L Ang-(1-7)能阻断AngⅡ增加心肌细胞间隙连接数目和大小。结论Ang-(1-7)通过抑制磷酸化ERK1/2活性增加,从而拮抗AngⅡ上调培养新生鼠心肌细胞Cx43间隙连接。     

欣力胶囊对阿霉素所致心肌细胞损伤的保护作用

目的观察欣力胶囊对阿霉素(ADR)中毒心肌细胞的保护作用并探讨其机制。方法采用新生SD乳鼠心肌细胞做原代培养,复制ADR损伤心肌细胞模型,测定培养上清液多项生化指标,并运用流式细胞仪检测凋亡细胞。结果ADR(终浓度为10~(-6)M)可致上清液乳酸脱氢酶(LDH)释放量增加(P<0.01),同时细胞超氧化物歧化酶(SOD)活力下降而丙二醛(MDA)含量升高(P<0.01),欣力胶囊(0.025～0.1 mg/mL)可呈浓度依赖性地降低LDH活力,增加细胞SOD活力和降低MDA含量(P<0.05或P<0.01)。流式细胞仪检测欣力胶囊能降低心肌细胞凋亡率,证实了欣力胶囊的保护作用。结论欣力胶囊能够拮抗ADR引起的自由基脂质过氧化,从而保护心肌细胞。     

A-kinase anchoring protein targeting of protein kinase A in the heart

There is increasing evidence that subcellular targeting of signaling molecules is an important means of regulating the protein kinase A (PKA) pathway. Subcellular organization of the signaling molecules in the PKA pathway insures that a signal initiated at the receptor level is transferred efficiently to a PKA substrate eliciting some cellular response. This subcellular targeting appears to regulate the function of a highly specialized cell such as the cardiac myocyte. This review focuses on A-kinase anchoring proteins (AKAPs) which are expressed in the heart. It has been determined that, of the approximately 13 different AKAPs expressed in cardiac tissue, several of these are expressed in cardiac myocytes. These AKAPs bind several PKA substrates and some appear to regulate PKA-dependent phosphorylation of these substrates. AKAP tethering of PKA may be essential for efficient regulation of cardiac muscle contraction. The ability of an AKAP to anchor PKA may be altered in the failing heart, thus compromising the ability of the myocyte to respond to stimuli which elicit the PKA pathway.     

新型缺血再灌注模式诱导小鼠心肌细胞凋亡

目的 探讨联用垂体后叶素(以下简称Pit)及硝酸甘油(NG)造成缺血再灌注损伤,诱导小鼠心肌细胞凋亡的实验条件及有关机制.方法 以昆明种小鼠为实验对象,单纯经腹腔注入20μ/kg的Pit者为Pit组:30min后再注入10mg/kg的NG者为Pit和NG联用组,记录两组0,5,20,33,60min的心电图(以下简称ECG).80min取出小鼠心脏,用透射电镜及DNA琼脂糖胶电泳观察心肌凋亡的发生.结果 ECG表明在5min及33min前后,t波高度发生显著变化(P<0.05),电泳出现凋亡特征性梯带,电镜下可观察到染色体浓集、边聚等心肌细胞凋亡的特征性变化.结论Pit和NG联用能有效地诱导小鼠心肌凋亡,其机制可能与缺血再灌注损伤有关.     

Phenylephrine promotes phosphorylation of Bad in cardiac myocytes through the extracellular signal-regulated kinases 1/2 and protein kinase A

Studies in non-cardiomyocytic cells have shown that phosphorylation of the Bcl-2 family protein Bad on Ser-112, Ser-136 and Ser-155 decreases its pro-apoptotic activity. Both phenylephrine (100 microM) and the cell membrane-permeating cAMP analog, 8-(4-chlorophenylthio)-cAMP (100 microM), protected against 2-deoxy-D-glucose-induced apoptosis in neonatal rat cardiac myocytes as assessed by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL). In cardiac myocytes, phenylephrine primarily stimulates the alpha-adrenoceptor, but, at high concentrations (100 microM), it also increases the activity of the cAMP-dependent protein kinase, protein kinase A (PKA) through the beta-adrenoceptor. Phenylephrine (100 microM) promoted rapid phosphorylation of Bad(Ser-112) and Bad(Ser-155), though we were unable to detect phosphorylation of Bad(Ser-136). Phosphorylation of Bad(Ser-112) was antagonized by either prazosin or propranolol, indicating that this phosphorylation required stimulation of both alpha(1)- and beta-adrenoceptors. Phosphorylation of Bad(Ser-155) was antagonized only by propranolol and was thus mediated through the beta-adrenoceptor. Inhibitor studies and partial purification of candidate kinases by fast protein liquid chromatography showed that the p90 ribosomal S6 kinases, p90RSK2/3 [which are activated by the extracellular signal-regulated kinases 1 and 2 (ERK1/2)] directly phosphorylated Bad(Ser-112), whereas the PKA catalytic subunit directly phosphorylated Bad(Ser-155). However, efficient phosphorylation of Bad(Ser-112) also required PKA activity. These data suggest that, although p90RSK2/3 phosphorylate Bad(Ser-112) directly, phosphorylation of this site is enhanced by phosphorylation of Bad(Ser-155). These phosphorylations potentially diminish the pro-apoptotic activity of Bad and contribute to the cytoprotective effects of phenylephrine and 8-(4-chlorophenylthio)-cAMP.     

Alterations in ventricular myocyte contraction caused by C-type natriuretic peptide and nitric oxide in eNOS-/- mice

Lack of endothelial nitric oxide synthase (eNOS) may affect the sensitivity of cyclic GMP signaling through soluble guanylyl cyclase (sGC). We hypothesized that in eNOS knockout (eNOS-/-) mice, stimulation of guanylyl cyclase would have enhanced effects inhibiting cardiac contraction. We measured cell shortening and calcium transients in isolated ventricular myocytes from adult eNOS-/- and wild-type (WT) mice after stimulating particulate guanylyl cyclase (pGC) with C-type natriuretic peptide (CNP, 10(-8) and 10(-7) M) or sGC with S-nitroso-N-acetyl-penicillamine (SNAP, NO donor, 10(-6) and 10(-5) M). Although sGC activity was increased by +71% in eNOS-/-, SNAP had similar effects in the two groups (%shortening -39% control vs. -37% eNOS-/-), suggesting that the cyclic GMP pathway was desensitized in eNOS-/- myocytes. CNP had significantly smaller effects on cell contraction (%shortening -34% control vs. -14% eNOS-/-) and pGC activity was not changed in eNOS-/- myocytes. Similar effects were also produced by guanylin and carbon monoxide, stimulators of pGC and sGC. CNP's effects on Ca(2+) transients were also attenuated in eNOS-/- myocytes. SNAP did not alter Ca(2+) transients in eNOS-/- or control cells. In the eNOS-/- mice, cyclic GMP-dependent protein kinase and cyclic AMP phosphodiesterase activity were reduced. This study demonstrated that the downstream cyclic GMP pathway was attenuated in eNOS-/- mice and this was partially compensated for by increased sGC, but not pGC activity in ventricular myocytes.     

PKCepsilon activation augments cardiac mitochondrial respiratory post-anoxic reserve--a putative mechanism in PKCepsilon cardioprotection

Modest cardiac-overexpression of constitutively active PKCepsilon (aPKCepsilon) in transgenic mice evokes cardioprotection against ischemia. As aPKCepsilon interacts with mitochondrial respiratory-chain proteins we hypothesized that aPKCepsilon modulates respiration to induce cardioprotection. Using isolated cardiac mitochondria wild-type and aPKCepsilon mice display similar basal mitochondrial respiration, rate of ATP synthesis and adenosine nucleotide translocase (ANT) functional content. Conversely, the aPKCepsilon mitochondria exhibit modest hyperpolarization of their inner mitochondrial membrane potential (DeltaPsi(m)) compared to wild-type mitochondrial by flow cytometry. To assess whether this hyperpolarization engenders resilience to simulated ischemia, anoxia-reoxygenation experiments were performed. Mitochondria were exposed to 45 min anoxia followed by reoxygenation. At reoxygenation, aPKCepsilon mitochondria recovered ADP-dependent respiration to 44 +/- 3% of baseline compared to 28 +/- 2% in WT controls (P = 0.03) in parallel with enhanced ATP synthesis. This preservation in oxidative phosphorylation is coupled to greater ANT functional content [42% > concentration of atractyloside for inhibition in the aPKCepsilon mitochondria vs. WT control (P < 0.0001)], retention of mitochondrial cytochrome c and conservation of DeltaPsi(m). These data demonstrate that mitochondria from PKCepsilon activated mice are intrinsically resilient to anoxia-reoxygenation compared to WT controls. This resilience is in part due to enhanced recovery of oxidative phosphorylation coupled to maintained ANT activity. As maintenance of ATP is a prerequisite for cellular viability we conclude that PKCepsilon activation augmented mitochondrial respiratory capacity in response to anoxia-reoxygenation may contribute to the PKCepsilon cardioprotective program.     

Endothelin-converting enzyme-1-mediated signaling in adult rat ventricular myocyte contractility and apoptosis during sepsis

We hypothesized that modulation of endothelin-converting enzyme-1 (ECE-1) activity would affect phosphorylation of p38-mitogen activated protein kinase (p38-MAPK) and potentiate apoptosis in adult rat ventricular myocytes (ARVMs) during sepsis. The activity of ECE-1 in ARVMs was altered by increasing the substrate availability for ECE-1 by exogenous administration of bigendothelin-1 (bigET-1, 100 nM) and by inhibiting ECE-1 using FR901533 (10 microM) for 24-h. FR901533 significantly decreased the concentration of ET-1 in both sham and sepsis groups. FR901533 decreased p38-MAPK phosphorylation in sepsis but not in sham group. BigET-1 upregulated p38-MAPK phosphorylation, produced hypertrophy, decreased cell viability and reversed FR901533-induced down-regulation of p38-MAPK phosphorylation in both groups. Although, FR901533 did not affect cell cross-sectional area, it significantly reduced the viability of ARVM in both groups. The peak shortening of sham ARVMs was elevated by bigET-1, FR901533 and pretreatment with FR901533 followed by bigET-1. However, the contractility of septic ARVMs was not altered by either bigET-1 or FR901533 treatments per se. Septic ARVM exhibited significantly increased caspase-3 activity at 12 and 24-h. Pretreatment with FR901533 significantly elevated caspase-3 activity in both sham and sepsis group. The data demonstrated that bigET-1-induced hypertrophy in septic ARVM correlates with an ECE-1 dependent-activation of p38-MAPK. The results suggest that non-responsiveness of ARVM to bigET-1 is due to ECE-1 dependent apoptosis. We concluded that ECE-1 may play a crucial role in ARVM dysfunction via increased caspase-3 activity and p38-MAPK phosphorylation during sepsis.     

MAPK信号通路在肝癌发生发展及治疗中的作用

丝裂原活化蛋白激酶(MAPK)信号通路的异常活化与肝癌的发生、发展、转移密切相关。介绍了MAPK通路蛋白在肝癌中的表达及其在肝癌增殖、分化、转移中的作用,阐述了MAPK信号通路在肝癌治疗及预后评价中的价值。认为MAPK信号通路在肝癌的发生发展及治疗中发挥非常重要的作用,是肝癌治疗及预后评价的潜在分子靶点。     

Integration of calcium with the signaling network in cardiac myocytes

Calcium has evolved as global intracellular messenger for signal transduction in the millisecond time range by reversibly binding to calcium-sensing proteins. In the cardiomyocyte, ion pumps, ion exchangers and channels keep the cytoplasmic calcium level at rest around approximately 100 nM which is more than 10,000-fold lower than outside the cell. Intracellularly, calcium is mainly stored in the sarcoplasmic reticulum, which comprises the bulk of calcium available for the heartbeat. Regulation of cardiac function including contractility and energy production relies on a three-tiered control system, (i) immediate and fast feedback in response to mechanical load on a beat-to-beat basis (Frank-Starling relation), (ii) more sustained regulation involving transmitters and hormones as primary messengers, and (iii) long-term adaptation by changes in the gene expression profile. Calcium signaling over largely different time scales requires its integration with the protein kinase signaling network which is governed by G-protein-coupled receptors, growth factor and cytokine receptors at the surface membrane. Short-term regulation is dominated by the beta-adrenergic system, while long-term regulation with phenotypic remodeling depends on sustained signaling by growth factors, cytokines and calcium. Mechanisms and new developments in intracellular calcium handling and its interrelation with the MAPK signaling pathways are discussed in detail.     

Redefining the roles of p38 and JNK signaling in cardiac hypertrophy: dichotomy between cultured myocytes and animal models

The mitogen-activated protein kinase (MAPK) signaling pathways serve as pivotal transducers of diverse biologic functions including cell growth, differentiation, proliferation, and apoptosis. The c-Jun N-terminal kinases (JNKs) and p38 kinases constitute two important branches of the greater MAPK signaling cascade that function as specialized transducers of stress or injury responses, hence they are subclassified as stress-activated protein kinases (SAPKs). In the myocardium, both p38 and JNK transduction cascades have been implicated in regulating the hypertrophic response, as well as cardiomyopathy and heart failure. Most reports proposing a pro-hypertrophic regulatory role for JNK and p38 signaling placed a heavy or exclusive reliance on culture-based models of cellular growth. More recently, a number of studies in genetically modified animal models have challenged the previously proposed role of JNK and p38 as pro-hypertrophic signaling effectors in the myocardium. This review will discuss an increasing body of evidence suggesting that the SAPKs (JNK and p38) do not positively regulate cardiac hypertrophy in vivo, but in fact may actually serve as negative regulators of this response in the adult heart. However, SAPK signaling is likely maladaptive, despite its putative anti-hypertrophic role in vivo, given the observation of dilated cardiomyopathy and heart failure in gain-of-function transgenic models.     

自发性高血压大鼠心肌丝裂素活化蛋白激酶活性增加

新近研究表明丝裂素活化蛋白激酶（MAPK）是细胞增殖肥大的重要酶类，为各种细胞外的生长刺激信号引起细胞内信息传递的共同通路或汇聚点。本文通过观察自发性高血压大鼠（SHR）心肌MAPK活性和心肌肥大的关系，探讨SHR心肌肥大发生的可能细胞内信息传递机制。方法：4个月的SHR和WKY大鼠各8只，以心重／体重的比值表示心肌肥厚的程度，采用胶内磷酸化法测定心肌MAPK活性。结果：与WKY大鼠比较，SHR心肌MAPK活性增加107.0％（P＜0．01），心肌肥大程度增加38．3％（P＜0．01）。心肌MAPK活性与心肌肥大程度呈显著正相关（r=0．708，P＜0．05）。结论：SHR心肌肥厚可能涉及MAPK。     

CB1 cannabinoid receptor deficiency promotes cardiac remodeling induced by pressure overload in mice

Background

The endocannabinoid system is known to play a role in regulating myocardial contractility, but the influence of cannabinoid receptor 1 (CB1) deficiency on chronic heart failure (CHF) remains unclear. In this study we attempted to investigate the effect of CB1 deficiency on CHF induced by pressure overload and the possible mechanisms involved.

Methods and results

A CHF model was created by transverse aortic constriction (TAC) in both CB1 knockout mice and wild-type mice. CB1 knockout mice showed a marked increase of mortality due to CHF from 4 to 8 weeks after TAC (p = 0.021). Five weeks after TAC, in contrast to wild-type mice, CB1 knockout mice had a higher left ventricular (LV) end-diastolic pressure, lower rate of LV pressure change (± dp/dt max), lower LV contractility index, and a larger heart weight to body weight ratio and lung weight to body weight ratio compared with wild-type mice (all p < 0.05–0.001). Phosphorylation of the epidermal growth factor receptor (EGFR) and mitogen-activated protein kinases (P38 and ERK) was higher in CB1 knockout mice than that in wild-type mice. In cultured neonatal rat cardiomyocytes, a CB1 agonist reduced cAMP production stimulated by isoproterenol or forskolin, and suppressed phosphorylation of the EGFR, P38, and ERK, while the inhibitory effect of a CB1 agonist on EGFR phosphorylation was abrogated by CB1 knockdown.

Conclusion

These findings indicate that cannabinoid receptor 1 inactivation promotes cardiac remodeling by enhancing the activity of the epidermal growth factor receptor and mitogen-activated protein kinases.     

辛伐他汀对大鼠心肌细胞肥大及蛋白激酶B表达的影响

目的观察辛伐他汀对血清诱导培养大鼠心肌细胞肥大的影响,探讨磷脂酰肌醇3激酶(PI3K)/蛋白激酶B(PKB)途径在辛伐他汀调控心肌细胞肥大中的信号转导作用。方法以培养的新生SpragueDawley(SD)大鼠心肌细胞为实验模型,应用图像分析系统测定心肌细胞表面积,[3H]亮氨酸掺入法测定心肌细胞蛋白合成速率,逆转录聚合酶链式反应(RTPCR)检测心钠素(ANP)mRNA表达,RTPCR和蛋白免疫印迹法(Westernblot)检测PKB的mRNA和蛋白表达水平。结果(1)15%血清组干预24h后心肌细胞表面积(1611.16±160.75)μm2显著高于无血清对照组(538.04±118.60)μm2,并有统计学意义(P<0.01);给予辛伐他汀和血清共同干预后,随着辛伐他汀浓度的增加,心肌细胞表面积呈递减趋势,其中10-5mol/L和10-6mol/L组分别为(799.84±167.70)μm2和(1076.88±199.28)μm2,均显著低于血清组(P<0.01)。(2)在15%血清刺激后,心肌细胞[3H]亮氨酸掺入率为(2360±106)计数/min·孔,明显高于无血清对照组(1305±92)计数/min·孔,并有统计学意义(P<0.01);10-5和10-6mol/L辛伐他汀组[3H]亮氨酸掺入率分别为(1707±101)计数/min·孔和(1962±125)计数/min·孔,均较血清组明显降低(P<0.01)。(3)随着辛伐他汀浓度的增加,心肌细胞ANP的mRNA表达水平逐渐降低,其中10-5和10-6mol/L辛伐他汀组分别为0.29±0.03和0.40±0.03,与单纯血清干预组(0.60±0.03)比较明显降低,差异非常显著(P<0.01)。(4)心肌细胞PKB的mRNA和蛋白表达水平均随辛伐他汀浓度的增加而呈递减趋势,其中10-5、10-6mol/L辛伐他汀组PKBmRNA表达水平为0.28±0.02和0.36±0.03,明显低于血清干预组(0.51±0.03),并有统计学意义(P<0.01)。上述两组PKB蛋白表达水平分别为42.41±2.83和45.68±3.43,也较血清组(60.80±3.49)显著降低(P<0.01)。结论辛伐他汀能够抑制血清诱导的心肌细胞肥大,PKB表达水平下调可能是其分子生物学机制之一。     

蛋白激酶C在精氨酸加压素诱导的心肌成纤维细胞诱导型一氧化氮合酶-一氧化氮系统活性增高中的作用

目的:观察蛋白激酶C(PKC)在精氨酸加压素(AVP)诱导下仔鼠心肌成纤维细胞(CFs)诱导型一氧化氮合酶(i NOS)-一氧化氮(NO)系统活性增高中的作用。方法:胰酶消化法分离培养Sprague-Dawley仔鼠CFs,硝酸还原酶法、分光光度法和逆转录-聚合酶链式反应(RT-PCR)检测CFs NO含量、一氧化氮合酶(NOS)活性和i NOS mRNA表达。结果:AVP显著提高CFs i NOS-NO系统活性;PKC抑制剂chelerythrine剂量依赖性地抑制AVP对CFs i NOS-NO系统活性的提高作用,其中10-6mol/L chelerythrine可将AVP诱导下CFs i NOS-NO系统活性抑制到与基础状态近似水平。结论:PKC参与了AVP诱导下CFs i NOS-NO系统活性的提高,PKC有可能成为阻断或逆转心肌纤维化新的干预靶点。