Reduction of Na/K-ATPase potentiates marinobufagenin-induced cardiac dysfunction and myocyte apoptosis

Decreases in cardiac Na/K-ATPase have been documented in patients with heart failure. Reduction of Na/K-ATPase α1 also contributes to the deficiency in cardiac contractility in animal models. Our previous studies demonstrate that reduction of cellular Na/K-ATPase causes cell growth inhibition and cell death in renal proximal tubule cells. To test whether reduction of Na/K-ATPase in combination with increased cardiotonic steroids causes cardiac myocyte death and cardiac dysfunction, we examined heart function in Na/K-ATPase α1 heterozygote knock-out mice (α1(+/-)) in comparison to wild type (WT) littermates after infusion of marinobufagenin (MBG). Adult cardiac myocytes were also isolated from both WT and α1(+/-) mice for in vitro experiments. The results demonstrated that MBG infusion increased myocyte apoptosis and induced significant left ventricle dilation in α1(+/-) mice but not in their WT littermates. Mechanistically, it was found that in WT myocytes MBG activated the Src/Akt/mTOR signaling pathway, which further increased phosphorylation of ribosome S6 kinase (S6K) and BAD (Bcl-2-associated death promoter) and protected cells from apoptosis. In α1(+/-) myocytes, the basal level of phospho-BAD is higher compared with WT myocytes, but MBG failed to induce further activation of the mTOR pathway. Reduction of Na/K-ATPase also caused the activation of caspase 9 but not caspase 8 in these cells. Using cultures of neonatal cardiac myocytes, we demonstrated that inhibition of the mTOR pathway by rapamycin also enabled MBG to activate caspase 9 and induce myocyte apoptosis.     

Noradrenergic stimulation of BDNF synthesis in astrocytes: mediation via alpha1- and beta1/beta2-adrenergic receptors

Brain-derived neurotrophic factor (BDNF) synthesis in astrocytes induced by noradrenaline (NA) is a receptor-mediated process utilizing two parallel adrenergic pathways: beta1/beta2-adrenergic/cAMP and the novel alpha1-adrenergic/PKC pathway. BDNF is produced by astrocytes, in addition to neurons, and the noradrenergic system plays a role in controlling BDNF synthesis. Since astrocytes express various subtypes of alpha- and beta-adrenergic receptors that have the potential to be activated by synaptically released NA, we focused our present study on the mediatory role of adrenergic receptors in the noradrenergic up-regulation of BDNF synthesis in cultured neonatal rat cortical astrocytes. NA (1 microM) elevates BDNF levels by four-fold after 6 h of incubation. Its stimulation was partly inhibited by either the beta1-adrenergic antagonist atenolol, the beta2-adrenergic antagonist ICI 118,551, or by the alpha1-adrenergic antagonist prazosin, while the alpha2-adrenergic antagonist yohimbine showed no effect. BDNF levels in astrocytes were increased by the specific beta1-adrenergic agonist dobutamine and the beta2-adrenergic agonist salbutamol, as well as by adenylate cyclase activation (by forskolin) and PKA activation (by dBcAMP). However, none of the tested agonists or mediators of the intracellular beta-adrenergic pathways were able to reach the level of NA's stimulatory effect. BDNF cellular levels were also elevated by the alpha1-adrenergic agonist methoxamine, but not by the alpha2-adrenergic agonist clonidine. The increase in intracellular Ca2+ by ionophore A23187 showed no effect, whereas PKC activation by phorbol 12-myristate 13-acetate (TPA) potently stimulated BDNF levels in the cells. The methoxamine-stimulated BDNF synthesis was inhibited by desensitizing pretreatment with TPA, indicating that the alpha1-stimulation was mediated via PKC activation. In conclusion, the synthesis of astrocytic BDNF stimulated by noradrenergic neuronal activity is an adaptable process using multiple types (alpha1 and beta1/beta2) of adrenergic receptor activation.     

Neutrophil apoptosis in autoimmune Fas-defective MRL lpr/lpr mice

The apoptosis-defective lpr (fas) mutation in MRL mice causes the early onset of a lupus-like autoimmune disease with concomitant inflammation. In order to analyse the consequences of the impaired Fas-dependent apoptosis on inflammation, the susceptibility to apoptosis of polymorphonuclear leukocytes (PMN), obtained from MRL lpr/lpr mice, has been studied. Peritoneal PMN from lpr/lpr and control (+/+) mice were recruited with a mild inflammatory stimulus. The number of cells collected from the peritoneal cavity of young lpr/lpr mice was comparable to that obtained from age-matched control mice, indicating that PMN homeostasis is maintained regardless of the loss-of-function Fas mutation. Recruited neutrophils were exposed in culture to apoptosis-inducing stimuli. Treatment with agonist anti-Fas antibody increased apoptosis of +/+ PMN, but did not affect lpr/lpr PMN which do not express Fas on their surface. However, lpr/lpr PMN could undergo both spontaneous and stimulus-induced apoptosis in a fashion comparable to or higher than that of control +/+ mice. Analysis of mRNA expression revealed that lpr/lpr PMN have reduced expression of IL-18, whereas IL-1beta, IFNgamma, caspase 1 and caspase 3 are expressed at levels comparable to those of +/+ cells. However, caspase-3-like activity was higher in PMN from lpr/lpr mice than in +/+ cells, and correlated with enhanced apoptosis. It could be concluded that in young, uncompromised lpr/lpr mice, PMN homeostasis is still fully regulated through the involvement of Fas-independent, compensatory, apoptotic mechanisms. This could include an increased participation of caspase 3 in the apoptotic pathway, consequent to enhanced activation of the enzyme and to the decreased production of IL-18, which acts as a competitive caspase 3 substrate.     

Overexpression of beta2-adrenergic receptors cAMP-dependent protein kinase phosphorylates and modulates slow delayed rectifier potassium channels expressed in murine heart: evidence for receptor/channel co-localization

The cardiac slow delayed rectifier potassium channel (IKs), comprised of (KCNQ1) and beta (KCNE1) subunits, is regulated by sympathetic nervous stimulation, with activation of beta-adrenergic receptors PKA phosphorylating IKs channels. We examined the effects of 2-adrenergic receptors (beta2-AR) on IKs in cardiac ventricular myocytes from transgenic mice expressing fusion proteins of IKs subunits and hbeta2-ARs. KCNQ1 and beta2-ARs were localized to the same subcellular regions, sharing intimate localization within nanometers of each other. In IKs/B2-AR myocytes, IKs density was increased, and activation shifted in the hyperpolarizing direction; IKs was not further modulated by exposure to isoproterenol, and KCNQ1 was found to be PKA-phosphorylated. Conversely, beta2-AR overexpression did not affect L-type calcium channel current (ICaL) under basal conditions with ICaL remaining responsive to cAMP. These data indicate intimate association of KCNQ1 and beta2-ARs and that beta2-AR signaling can modulate the function of IKs channels under conditions of increased beta2-AR expression, even in the absence of exogenous beta-AR agonist.     

Cytochrome c and insect cell apoptosis

Abstract The role of cytochrome c in insect cell apoptosis has drawn considerable attention and has been subject to considerable controversy. In Drosophila, the majority of studies have demonstrated that cytochrome c may not be involved in apoptosis, although there are conflicting reports. Cytochrome c is not released from mitochondria into the cytosol and activation of the initiator caspase Dronc or effector caspase Drice is not associated with cytochrome c during apoptosis in Drosophila SL2 cells or BG2 cells. Cytochrome c failed to induce caspase activation and promote caspase activation in Drosophila cell lysates, but remarkably caused caspase activation in extracts from human cells. Knockdown of cytochrome c does not protect cells from apoptosis and over‐expression of cytochrome c also does not promote apoptosis. Structural analysis has revealed that cytochrome c is not required for Dapaf‐1 complex assembly. In Lepidoptera, the involvement of cytochrome c in apoptosis has been demonstrated by the accumulating evidence. Cytochrome c release from mitochondria into cytosol has been observed in different cell lines such as Spodoptera frugiperda Sf9, Spodoptera litura Sl‐1 and Lymantria dispar LdFB. Silencing of cytochrome c expression significantly affected apoptosis and activation of caspase and the addition of cytochrome c to cell‐free extracts results in caspase activation, suggesting the activation of caspase is dependent on cytochrome c. Although Apaf‐1 has not been identified in Lepidoptera, the inhibitor of apoptosome formation can inhibit apoptosis and caspase activation. Cytochrome c may be exclusively required for Lepidoptera apoptosis.     

Cardiac myocyte apoptosis provokes adverse cardiac remodeling in transgenic mice with targeted TNF overexpression

Although cardiac myocyte apoptosis has been detected in explanted hearts from patients with end-stage dilated and ischemic cardiomyopathy, the relative contribution of apoptotic cell death to left ventricular (LV) remodeling and cardiac decompensation is not known. To determine whether progressive cardiac myocyte apoptosis contributes to the transition from a hypertrophic to a dilated cardiac phenotype that is observed in transgenic myosin heavy chain secreted TNF (MHCsTNF) mice with cardiac restricted overexpression of tumor necrosis factor (TNF), we assessed cardiac myocyte apoptosis (using a DNA ligase technique) in MHCsTNF mice and littermate control mice in relation to serial changes in LV structure, which was assessed using MRI. The prevalence of cardiac myocyte apoptosis increased progressively from 4 to 12 wk as the hearts of the MHCsTNF mice underwent the transition from a concentric hypertrophic to a dilated cardiac phenotype. Treatment of the MHCsTNF mice with the broad-based caspase inhibitor N-[(1,3-dimethylindole-2-carbonyl)-valinyl]-3-amino4-oxo-5-fluoropentanoic acid significantly decreased cardiac myocyte apoptosis and significantly attenuated LV wall thinning and adverse cardiac remodeling. Additional studies suggested that the TNF-induced decrease in Bcl-2 expression and activation of the intrinsic mitochondrial death pathway were responsible for the cardiac myocyte apoptosis observed in the MHCsTNF mice. These studies show that progressive cardiac myocyte apoptosis is sufficient to contribute to adverse cardiac remodeling in the adult mammalian heart through progressive LV wall thinning.     

NO induces a cGMP-independent release of cytochrome c from mitochondria which precedes caspase 3 activation in insulin producing RINm5F cells.

Exposure of RINm5F cells to interleukin-1beta and to several chemical NO donors such as sodium nitroprusside (SNP), SIN-1 and SNAP induce apoptotic events such as the release of cytochrome c from mitochondria, caspase 3 activation, Bcl-2 downregulation and DNA fragmentation. SNP exposure led to transient activation of soluble guanylate cyclase (sGC) and prolonged protein kinase G (PKG) activation but apoptotic events were not attenuated by inhibition of the sGC/PKG pathway. Prolonged activation of the cGMP pathway by exposing cells to the dibutyryl analogue of cGMP for 12 h induced both apoptosis and necrosis, a response that was abolished by the PKG inhibitor KT5823. These results suggest that NO-induced apoptosis in the pancreatic beta-cell line is independent of acute activation of the cGMP pathway.     

Akt regulates cell survival and apoptosis at a postmitochondrial level

Phosphoinositide 3 kinase/Akt pathway plays an essential role in neuronal survival. However, the cellular mechanisms by which Akt suppresses cell death and protects neurons from apoptosis remain unclear. We previously showed that transient expression of constitutively active Akt inhibits ceramide-induced death of hybrid motor neuron 1 cells. Here we show that stable expression of either constitutively active Akt or Bcl-2 inhibits apoptosis, but only Bcl-2 prevents the release of cytochrome c from mitochondria, suggesting that Akt regulates apoptosis at a postmitochondrial level. Consistent with this, overexpressing active Akt rescues cells from apoptosis without altering expression levels of endogenous Bcl-2, Bcl-x, or Bax. Akt inhibits apoptosis induced by microinjection of cytochrome c and lysates from cells expressing active Akt inhibit cytochrome c induced caspase activation in a cell-free assay while lysates from Bcl-2-expressing cells have no effect. Addition of cytochrome c and dATP to lysates from cells expressing active Akt do not activate caspase-9 or -3 and immunoprecipitated Akt added to control lysates blocks cytochrome c-induced activation of the caspase cascade. Taken together, these data suggest that Akt inhibits activation of caspase-9 and -3 by posttranslational modification of a cytosolic factor downstream of cytochrome c and before activation of caspase-9.     

Herpes simplex virus blocks apoptosis by precluding mitochondrial cytochrome c release independent of caspase activation in infected human epithelial cells

Expression of HSV-1 genes leads to the induction of apoptosis in human epithelial HEp-2 cells but the subsequent synthesis of infected cell protein prevents the process from killing the cells. Thus, viruses unable to produce appropriate prevention factors are apoptotic. We now report that the addition of either a pancaspase inhibitor or caspase-9-specific inhibitor prevented cells infected with an apoptotic HSV-1 virus from undergoing cell death. This result indicated that HSV-1-dependent apoptosis proceeds through the mitochondrial apoptotic pathway. However, the pancaspase inhibitor did not prevent the release of cytochrome c from mitochondria, implying that caspase activation is not required for this induction of cytochrome c release by HSV-1. The release of cytochrome c was first detected at 9 hpi while caspase-9, caspase-3 and PARP processing were detected at 12 hpi. Finally, Bax accumulated at mitochondria during apoptotic, but not wild type HSV-1 infection. Together, these findings indicate that HSV-1 blocks apoptosis by precluding mitochondrial cytochrome c release in a caspase-independent manner and suggest Bax as a target in infected human epithelial cells.     

Retinoid-related molecules require caspase 9 for the effective release of Smac and the rapid induction of apoptosis

Certain retinoid-related molecules (RRMs) with agonist or antagonist activities have been described to induce apoptosis in a variety of cancer cell lines and show promise for the treatment of cancer. Similar to other chemotherapeutic drugs, these retinoid analogs have been suggested to induce apoptosis through the intrinsic pathway, which requires the release of cytochrome c from the mitochondria for the effective activation of caspase 9. Expression of a catalytically inactive form of caspase 9, which functions as a dominant negative mutant, inhibits the induction of DEVDase activity and nuclear fragmentation by selective RRMs. Whereas the RRMs could induce the release of cytochrome c in the absence of caspase 9 activity, the later is necessary for the effective release of Smac/Diablo from the mitochondria. Furthermore, overexpression of Bcl-2 or Bcl-X(L) also inhibits RRM-induced apoptosis. We demonstrate that activation of caspase 2 by the agonist MX2870-1 requires caspase 9 activity and is inhibited by Bcl-2 overexpression. In contrast, the antagonist MX781 induces cleavage of procaspase 2 upstream of mitochondria and independently of caspase 9. Thus, two retinoid analogs with unique characteristics activate two distinct apical caspases (2 or 9) to initiate apoptosis. In addition to caspase-mediated cell death, sustained exposure to the RRMs can also lead to loss of cell viability in cells lacking caspase 9 activity or in cells stimulated in the presence of the caspase inhibitor Z-VAD-fmk. Moreover, MX2870-1 and MX781 produce cell cycle arrest independently of caspase activity and the retinoid receptors.     

Cardiomyocyte apoptosis in autoimmune cardiomyopathy: mediated via endoplasmic reticulum stress and exaggerated by norepinephrine

Evidence suggests that the autoimmune cardiomyopathy produced by a peptide corresponding to the sequence of the second extracellular loop of the beta(1)-adrenergic receptor (beta(1)-EC(II)) is mediated via a biologically active anti-beta(1)-EC(II) antibody, but the mechanism linking the antibody to myocyte apoptosis and cardiac dysfunction has not been well elucidated. Since the beta(1)-EC(II) autoantibody is a partial beta(1)-agonist, we speculate that the cardiomyopathy is produced by the beta(1)-receptor-mediated stimulation of the CaMKII-p38 MAPK-ATF6 signaling pathway and endoplasmic reticulum (ER) stress, and that excess norepinephrine (NE) exaggerates the cardiomyopathy. Rabbits were randomized to receive beta(1)-EC(II) immunization, sham immunization, NE pellet, or beta(1)-EC(II) immunization plus NE pellet for 6 mo. Heart function was measured by echocardiography and catheterization. Myocyte apoptosis was determined by terminal deoxytransferase-mediated dUTP nick-end labeling and caspase-3 activity, whereas CaMKII, MAPK family (JNK, p38, ERK), and ER stress signals (ATF6, GRP78, CHOP, caspase-12) were measured by Western blot, immunohistochemistry, and kinase activity assay. beta(1)-EC(II) immunization produced progressive LV dilation, systolic dysfunction, and myocyte apoptosis. These changes were associated with activation of GRP78 and CHOP and increased cleavage of caspase-12, as well as increased CaMKII activity, increased phosphorylation of p38 MAPK, and nucleus translocation of cleaved ATF6. NE pellet produced additive effects. In addition, KN-93 and SB 203580 abolished the induction of ER stress and cell apoptosis produced by the beta(1)-EC(II) antibody in cultured neonatal cardiomyocytes. Thus ER stress occurs in autoimmune cardiomyopathy induced by beta(1)-EC(II) peptide, and this is enhanced by increased NE and caused by activation of the beta(1)-adrenergic receptor-coupled CaMKII, p38 MAPK, and ATF6 pathway.     

Dominant-negative c-Jun promotes neuronal survival by reducing BIM expression and inhibiting mitochondrial cytochrome c release

Sympathetic neurons require nerve growth factor for survival and die by apoptosis in its absence. Key steps in the death pathway include c-Jun activation, mitochondrial cytochrome c release, and caspase activation. Here, we show that neurons rescued from NGF withdrawal-induced apoptosis by expression of dominant-negative c-Jun do not release cytochrome c from their mitochondria. Furthermore, we find that the mRNA for BIM(EL), a proapoptotic BCL-2 family member, increases in level after NGF withdrawal and that this is reduced by dominant-negative c-Jun. Finally, overexpression of BIM(EL) in neurons induces cytochrome c redistribution and apoptosis in the presence of NGF, and neurons injected with Bim antisense oligonucleotides or isolated from Bim(-/-) knockout mice die more slowly after NGF withdrawal.     

Enzastaurin-induced apoptosis in glioma cells is caspase-dependent and inhibited by BCL-XL

The novel protein kinase C-beta inhibitor enzastaurin (ENZA) induced apoptosis in LNT-229 and T98G cells whereas A172 cells were resistant. Further, ENZA reduced proliferation in glioblastoma-initiating cells T 269 and T 323 but did not induce apoptosis. ENZA-induced apoptosis involved cleavage of caspases 3, 8, and 9 and led to mitochondrial cytochrome c release and was strongly suppressed by the broad spectrum caspase inhibitor zVAD-fmk but only slightly by the expression of the viral caspase 1/8 inhibitor cytokine response modifier-A. ENZA did not reduce the phosphorylation of protein kinase B (Akt), but of p70 S6 kinase and of its substrate S6 protein in T98G cells. Inhibition of the phosphatidylinositol 3 kinase signaling pathway did not restore sensitivity of A172 cells towards ENZA, and constitutively active Akt did not protect LNT-229 and T98G cells from ENZA-induced apoptosis. Dephosphorylation of glycogen synthase kinase 3beta, a biomarker of ENZA action, and cell death induction by ENZA were separately regulated. Inhibition or activation of Akt only weakly modulated ENZA-induced dephosphorylation of glycogen synthase kinase 3beta. In ENZA-resistant A172 cells, apoptosis ligand 2 (Apo2L.0)-induced cleavage of caspases 3, 8, and 9 was increased by ENZA, resulting in synergistic activity of ENZA and Apo2L.0.     

The N-terminal internal region of BLM is required for the formation of dots/rod-like structures which are associated with SUMO-1

Chemotherapeutic drug-induced apoptosis of human malignant glioma cells involves the death receptor-independent activation of caspases other than caspases 3 or 8 (Glaser et al., Oncogene 18, 5044-5053, 1999). Here, we report that caspases 1, 2, 3, 7, 8, and 9 are constitutively expressed in most human malignant glioma cell lines. Cytotoxic drug-induced apoptosisinvolves delayed activation of caspases 2, 7, and 9, but not 8 and 3, and is blocked by a broad spectrum caspase inhibitor, zVAD-fmk. Cytochrome c release from mitochondria precedes caspase activation during drug-induced apoptosis and is unaffected by zVAD-fmk or ectopic expression of the viral caspase inhibitor, crm-A. In contrast, ectopic expression of BCL-X(L) prevents drug-induced cytochrome c release, caspase activation and cell death. Thus, cancer chemotherapy targets the mitochondrial, caspase-dependent death pathway in human malignant glioma cells.     

Neuronal cell death caused by inhibition of intracellular cholesterol trafficking is caspase dependent and associated with activation of the mitochondrial apoptosis pathway

An elevated level of cholesterol in mitochondrial membranes of Niemann-Pick disease type C1 (NPC1) mouse brains and neural cells has been found to cause mitochondrial dysfunction. In this study, we demonstrate that inhibition of intracellular cholesterol trafficking in primary neurons by class 2 amphiphiles, which mimics the major biochemical and cellular feature of NPC1, led to not only impaired mitochondrial function but also activation of the mitochondrial apoptosis pathway. In activation of this pathway both cytochrome c and Smac/Diablo were released but apoptosis-inducing factor (AIF) was not involved. Treatment of the neurons with taurine, a caspase 9-specific inhibitor, could prevent the amphiphile-induced apoptotic cell death, suggesting that formation of apoptosome, followed by caspase 9 and caspase 3 activation, might play a critical role in the neuronal death pathway. Taken together, the mitochondria-dependent death cascade induced by blocking intracellular cholesterol trafficking was caspase dependent. The findings provide clues for both understanding the molecular basis of neurodegeneration in NPC1 disease and developing therapeutic strategies for treatment of this disorder.     

Distinct signaling functions for Shc isoforms in the heart

Thrombin activates protease-activated receptor-1 (PAR-1) and engages signaling pathways that influence the growth and survival of cardiomyocytes as well as extracellular matrix remodeling by cardiac fibroblasts. This study examines the role of Shc proteins in PAR-1-dependent signaling pathways that influence ventricular remodeling. We show that thrombin increases p46Shc/p52Shc phosphorylation at Tyr(239)/Tyr(240) and Tyr(317) (and p66Shc-Ser(36) phosphorylation) via a pertussis toxin-insensitive epidermal growth factor receptor (EGFR) transactivation pathway in cardiac fibroblasts; p66Shc-Ser(36) phosphorylation is via a MEK-dependent mechanism. In contrast, cardiac fibroblasts express beta(2)-adrenergic receptors that activate ERK through a pertussis toxin-sensitive EGFR transactivation pathway that does not involve Shc isoforms or lead to p66Shc-Ser(36) phosphorylation. In cardiomyocytes, thrombin triggers MEK-dependent p66Shc-Ser(36) phosphorylation, but this is not via EGFR transactivation (or associated with Shc-Tyr(239)/Tyr(240) and/or Tyr(317) phosphorylation). Importantly, p66Shc protein expression is detected in neonatal, but not adult, cardiomyocytes; p66Shc expression is induced (via a mechanism that requires protein kinase C and MEK activity) by Pasteurella multocida toxin, a Galpha(q) agonist that promotes cardiomyocyte hypertrophy. These results identify novel regulation of individual Shc isoforms in receptor-dependent pathways leading to cardiac hypertrophy and the transition to heart failure. The observations that p66Shc expression is induced by a Galpha(q) agonist and that PAR-1 activation leads to p66Shc-Ser(36) phosphorylation identifies p66Shc as a novel candidate hypertrophy-induced mediator of cardiomyocyte apoptosis and heart failure.     

瞬时受体电位香草酸亚型1激活通过抑制线粒体通透性转换孔开放保护急性心肌梗死小鼠的心肌细胞抗凋亡

瞬时受体电位香草酸亚型1（TRPV1）在心肌缺血激活后可传导心绞痛信号,释放神经肽,减轻心肌梗死后的心肌细胞凋亡。目前,TRPV1激活抑制心肌梗死后细胞凋亡的具体机制尚不清楚。线粒体通透性转换孔（MPTP）的开放与心肌细胞缺血再灌注损伤密切相关,抑制其开放可保护心肌缺血后的心肌细胞抗凋亡。本研究证明,TRPV1激活通过抑制MPTP开放而减少心肌细胞凋亡。首先,本研究利用左冠状动脉前降支结扎术建立了TRPV1基因敲除（TRPV1-/-）和野生型（WT）小鼠心肌梗死模型,辅以环孢素A（CSA）预处理抑制 MPTP开放,比较观察TRPV1、MPTP在心肌梗死中的作用。心肌组织切片氯化三苯基四氮唑（TTC）染色显示,心肌缺血24 h,TRPV1-/-小鼠的心肌梗死面积明显大于WT型小鼠。而经CSA预处理的TRPV1-/-小鼠比TRPV1-/-小鼠梗死面积明显减小。TUNEL检测心肌细胞凋亡指数（AI）揭示,WT型心肌梗死小鼠的AI明显低于TRPV1-/- 心肌梗死小鼠,而CSA预处理明显降低TRPV1-/-小鼠心肌细胞的AI。Western印迹检测胱天蛋白酶3、胱天蛋白酶9、Bcl-2、Bax、p53和细胞色素C（Cyt-C）水平。结果证明,TRPV1的激活可抑制MPTP的开放,减少线粒体Cyt-C的外溢,降低胱天蛋白酶9和胱天蛋白酶3的表达。GENMEN光度法检测MPTP开放实验显示,激活的TRPV1明显抑制了MPTP的开放。本研究证实,急性心肌梗死后的TRPV1激活可能通过抑制MPTP开放而抵抗心肌细胞凋亡,对心肌起保护作用。