Rats ; Animals ; Myocardial Reperfusion Injury/metabolism* ; Luteolin/metabolism* ; Down-Regulation ; Rats, Sprague-Dawley ; MicroRNAs/metabolism* ; Reperfusion Injury ; Apoptosis

BACKGROUND: Dysfunction of the gap junction channel protein connexin 43 (Cx43) contributes to myocardial ischemia/reperfusion (I/R)-induced ventricular arrhythmias. Cx43 can be regulated by small ubiquitin-like modifier (SUMO) modification. Protein inhibitor of activated STAT Y (PIASy) is an E3 SUMO ligase for its target proteins. However, whether Cx43 is a target protein of PIASy and whether Cx43 SUMOylation plays a role in I/R-induced arrhythmias are largely unknown. METHODS: Male Sprague-Dawley rats were infected with PIASy short hairpin ribonucleic acid (shRNA) using recombinant adeno-associated virus subtype 9 (rAAV9). Two weeks later, the rats were subjected to 45 min of left coronary artery occlusion followed by 2 h reperfusion. Electrocardiogram was recorded to assess arrhythmias. Rat ventricular tissues were collected for molecular biological measurements. RESULTS: Following 45 min of ischemia, QRS duration and QTc intervals statistically significantly increased, but these values decreased after transfecting PIASy shRNA. PIASy downregulation ameliorated ventricular arrhythmias induced by myocardial I/R, as evidenced by the decreased incidence of ventricular tachycardia and ventricular fibrillation, and reduced arrythmia score. In addition, myocardial I/R statistically significantly induced PIASy expression and Cx43 SUMOylation, accompanied by reduced Cx43 phosphorylation and plakophilin 2 (PKP2) expression. Moreover, PIASy downregulation remarkably reduced Cx43 SUMOylation, accompanied by increased Cx43 phosphorylation and PKP2 expression after I/R. CONCLUSION PIASy downregulation inhibited Cx43 SUMOylation and increased PKP2 expression, thereby improving ventricular arrhythmias in ischemic/reperfused rats heart.
Rats ; Male ; Animals ; Myocardial Reperfusion Injury/metabolism* ; Connexin 43/genetics* ; Sumoylation ; Down-Regulation ; Rats, Sprague-Dawley ; Arrhythmias, Cardiac/drug therapy* ; Myocardial Ischemia/metabolism* ; RNA, Small Interfering/metabolism*

Mitophagy is one of the important targets for the prevention and treatment of myocardial ischemia/reperfusion injury (MIRI). Moderate mitophagy can remove damaged mitochondria, inhibit excessive reactive oxygen species accumulation, and protect mitochondria from damage. However, excessive enhancement of mitophagy greatly reduces adenosine triphosphate production and energy supply for cell survival, and aggravates cell death. How dysfunctional mitochondria are selectively recognized and engulfed is related to the interaction of adaptors on the mitochondrial membrane, which mainly include phosphatase and tensin homolog deleted on chromosome ten (PTEN)-induced kinase 1/Parkin, hypoxia-inducible factor-1 α/Bcl-2 and adenovirus e1b19k Da interacting protein 3, FUN-14 domain containing protein 1 receptor-mediated mitophagy pathway and so on. In this review, the authors briefly summarize the main pathways currently studied on mitophagy and the relationship between mitophagy and MIRI, and incorporate and analyze research data on prevention and treatment of MIRI with Chinese medicine, thereby provide relevant theoretical basis and treatment ideas for clinical prevention of MIRI.
Humans ; Mitochondria/metabolism* ; Mitophagy/genetics* ; Myocardial Reperfusion Injury ; Protein Kinases/metabolism*

BACKGROUND: Sarcoplasmic reticulum calcium ATPase 2a (SERCA2a) is a key protein that maintains myocardial Ca 2+ homeostasis. The present study aimed to investigate the mechanism underlying the SERCA2a-SUMOylation (small ubiquitin-like modifier) process after ischemia/reperfusion injury (I/RI) in vitro and in vivo . METHODS: Calcium transient and systolic/diastolic function of cardiomyocytes isolated from Serca2a knockout (KO) and wild-type mice with I/RI were compared. SUMO-relevant protein expression and localization were detected by quantitative real-time PCR (RT-qPCR), Western blotting, and immunofluorescence in vitro and in vivo . Serca2a-SUMOylation, infarct size, and cardiac function of Senp1 or Senp2 overexpressed/suppressed adenovirus infected cardiomyocytes, were detected by immunoprecipitation, triphenyltetrazolium chloride (TTC)-Evans blue staining, and echocardiography respectively. RESULTS: The results showed that the changes of Fura-2 fluorescence intensity and contraction amplitude of cardiomyocytes decreased in the I/RI groups and were further reduced in the Serca2a KO + I/RI groups. Senp1 and Senp2 messenger ribose nucleic acid (mRNA) and protein expression levels in vivo and in cardiomyocytes were highest at 6 h and declined at 12 h after I/RI. However, the highest levels in HL-1 cells were recorded at 12 h. Senp2 expression increased in the cytoplasm, unlike that of Senp1. Inhibition of Senp2 protein reversed the I/RI-induced Serca2a-SUMOylation decline, reduced the infarction area, and improved cardiac function, while inhibition of Senp1 protein could not restore the above indicators. CONCLUSION I/RI activated Senp1 and Senp2 protein expression, which promoted Serca2a-deSUMOylation, while inhibition of Senp2 expression reversed Serca2a-SUMOylation and improved cardiac function.
Animals ; Mice ; Calcium/metabolism* ; Cysteine Endopeptidases/metabolism* ; Myocardial Reperfusion Injury/metabolism* ; Myocardium/metabolism* ; Myocytes, Cardiac/metabolism* ; Proteins/metabolism* ; Sarcoplasmic Reticulum Calcium-Transporting ATPases/genetics*

This study aimed to investigate the effect and underlying mechanism of Poria cocos polysaccharides(PCP) on myocardial cell apoptosis in the rat model of myocardial ischemia-reperfusion injury(MI/RI). Male SPF-grade SD rats were randomly divided into a sham group(saline), a model group(saline), low-and high-dose PCP groups(100 and 200 mg·kg~(-1)), and a fasudil group(10 mg·kg~(-1)), with 16 rats in each group. Except for the sham group, the other four groups underwent left anterior descending coronary artery ligation for 30 min followed by reperfusion for 2 h to establish the MI/RI model. The myocardial infarct area was assessed by TTC staining. Histological changes were observed through HE staining. Myocardial cell apoptosis was evaluated using TUNEL staining. Serum lactate dehydrogenase(LDH), creatine kinase MB(CK-MB), interleukin-1β(IL-1β) and IL-18 levels, myocardial superoxide dismutase(SOD) activity and malondialdehyde(MDA) levels were detected by ELISA. Protein expression of B-cell lymphoma 2(Bcl-2), Bcl-2 associated X protein(Bax), cleaved caspase-3, Ras homolog gene A(RhoA), myosin phosphatase target subunit 1(MYPT-1), phosphorylated MYPT-1(p-MYPT-1), and Rho-associated coiled-coil forming kinase 1(ROCK 1) were measured by Western blot. Pathological staining of myocardial tissue revealed that in the model group, there was focal necrosis of myocardial tissue, myocardial cell swelling, unclear boundaries, and neutrophil infiltration. These pathological changes were alleviated in the low-and high-dose PCP groups and the fasudil group. Compared with the model group, the low-and high-dose PCP groups and the fasudil group showed significantly reduced myocardial infarct area and myocardial cell apoptosis rate. Compared with the sham group, the model group exhibited elevated serum LDH, CK-MB, IL-1β and IL-18 levels, increased MDA levels, relative protein expression of Bax, cleaved caspase-3, RhoA, ROCK1 and p-MYPT-1, and decreased myocardial SOD levels and Bcl-2 protein expression. Compared with the model group, the PCP groups and the fasudil group showed lowered serum LDH, CK-MB, IL-1β and IL-18 levels, decreased MDA levels, relative protein expression of Bax, cleaved caspase-3, RhoA, ROCK1 and p-MYPT-1, and increased myocardial SOD levels and Bcl-2 protein expression. PCP exhibited a certain preventive effect on myocardial tissue pathological damage and myocardial cell apoptosis in MI/RI rats, possibly related to the inhibition of the Rho-ROCK signaling pathway activation, thereby reducing oxidative stress and inflammatory responses.
Rats ; Male ; Animals ; Myocardial Reperfusion Injury/drug therapy* ; bcl-2-Associated X Protein/metabolism* ; Rats, Sprague-Dawley ; Caspase 3/metabolism* ; Interleukin-18 ; Wolfiporia ; Signal Transduction ; Myocardial Infarction/drug therapy* ; Proto-Oncogene Proteins c-bcl-2/metabolism* ; Creatine Kinase, MB Form ; Apoptosis ; Polysaccharides/pharmacology* ; Superoxide Dismutase/metabolism* ; 1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine/analogs & derivatives*

OBJECTIVE: To explore the protective effect of Huoxin Pill (HXP) on acute myocardial ischemia-reperfusion (MIRI) injury in rats. METHODS: Seventy-five adult SD rats were divided into the sham-operated group, model group, positive drug group (diltiazem hydrochloride, DH), high dose group (24 mg/kg, HXP-H) and low dose group (12 mg/kg, HXP-L) of Huoxin Pill (n=15 for every group) according to the complete randomization method. After 1 week of intragastric administration, the left anterior descending coronary artery of the rat's heart was ligated for 45 min and reperfused for 3 h. Serum was separated and the levels of creatine kinase (CK), creatine kinase isoenzyme (CK-MB) and lactate dehydrogenase (LDH), superoxide dismutase (SOD), and malondialdehyde (MDA), hypersensitive C-reactive protein (hs-CRP) and interleukin-1β (IL-1β) were measured. Myocardial ischemia rate, myocardial infarction rate and myocardial no-reflow rate were determined by staining with Evans blue and 2,3,5-triphenyltetrazolium chloride (TTC). Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform (TCMSP) and Bioinformatics Analysis Tool for Molecular mechANism of Traditional Chinese Medicine (BATMAN) databases were used to screen for possible active compounds of HXP and their potential therapeutic targets; the results of anti-inflammatory genes associated with MIRI were obtained from GeneCards, Drugbank, Online Mendelian Inheritance in Man (OMIM), and Therapeutic Target Datebase (TTD) databases was performed; Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment were used to analyze the intersected targets; molecular docking was performed using AutoDock Tools. Western blot was used to detect the protein expression of Toll-like receptor 4 (TLR4)/nuclear factor kappa-B (NFκB)/NOD-like receptor protein 3 (NLRP3). RESULTS: Compared with the model group, all doses of HXP significantly reduced the levels of LDH, CK and CK-MB (P<0.05, P<0.01); HXP significantly increased serum activity of SOD (P<0.05, P<0.01); all doses of HXP significantly reduced the levels of hs-CRP and IL-1β (P<0.05, P<0.01) and the myocardial infarction rate and myocardial no-reflow rate (P<0.01). GO enrichment analysis mainly involved positive regulation of gene expression, extracellular space and identical protein binding, KEGG pathway enrichment mainly involved PI3K-Akt signaling pathway and lipid and atherosclerosis. Molecular docking results showed that kaempferol and luteolin had a better affinity with TLR4, NFκB and NLRP3 molecules. The protein expressions of TLR4, NFκB and NLRP3 were reduced in the HXP group (P<0.01). CONCLUSIONS HXP has a significant protective effect on myocardial ischemia-reperfusion injury in rats, and its effect may be related to the inhibition of redox response and reduction of the inflammatory response by inhibiting the TLR4NFκB/NLRP3 signaling pathway.
Humans ; Rats ; Animals ; NF-kappa B/metabolism* ; Myocardial Reperfusion Injury/drug therapy* ; NLR Family, Pyrin Domain-Containing 3 Protein ; Rats, Sprague-Dawley ; C-Reactive Protein ; Toll-Like Receptor 4 ; Phosphatidylinositol 3-Kinases/metabolism* ; Molecular Docking Simulation ; Signal Transduction ; Myocardial Infarction/drug therapy* ; Creatine Kinase ; L-Lactate Dehydrogenase/metabolism* ; Superoxide Dismutase/metabolism*

Fibroblast growth factor 21 (FGF21) is a growth factor with endocrine function in the fibroblast growth factor family. Previous reports have shown that FGF21 is involved in the regulation of energy metabolism and plays a protective role in cardiovascular diseases such as coronary heart disease, diabetes, non-alcoholic fatty liver disease and so on. Recent studies have found that FGF21 can induce autophagy in a variety of tissues and organs, and autophagy is involved in many pathological processes of cardiovascular diseases, including vascular calcification, atherosclerosis, and myocardial ischemia-reperfusion injury. Therefore, FGF21 may play a protective role in a variety of cardiovascular diseases by regulating autophagy. This article reviews the research progress on the protective role of FGF21 in cardiovascular diseases by inducing autophagy.
Autophagy/physiology* ; Cardiovascular Diseases/metabolism* ; Fibroblast Growth Factors/metabolism* ; Humans ; Myocardial Reperfusion Injury/metabolism*

Objective To explore the role and mechanism of microRNA-204(miR-204) carried by the exosomes of human umbilical cord-derived mesenchymal stem cells(hUC-MSC) in regulating the polarization of macrophages in a mouse model of myocardial ischemia-reperfusion(I/R) injury. Methods After the hUC-MSCs were isolated,cultured,and identified,their adipogenic and osteogenic differentiation capabilities were determined.The exosomes of hUC-MSCs were separated by ultracentrifugation,and the expression of CD81,CD63,tumor susceptibility gene 101(Tsg101),and calnexin in the exosomes was determined by Nanoparticle Tracking Analysis software,transmission electron microscopy,and Western blotting.Three groups(hUC-MSC,miR-204 mimic,and negative control) were designed for the determination of the expression of miR-204 in the cells and their exosomes by qRT-PCR.The C57BL/6J mice were randomly assigned into a sham operation group,an I/R group,a hUC-MSC exosomes group,a negative control group,and a miR-204 mimic group.Except the sham operation group,the I/R model was established by ligating the left anterior descending artery.The echocardiography system was employed to detect the heart function of mice.HE staining was employed to observe the pathological changes of mouse myocardium.ELISA was employed to determine the levels of interleukin-1β(IL-1β),tumor necrosis factor-α(TNF-α),arginase 1(Arg-1),and IL-10 in the myocardial tissue.After the macrophages of mouse myocardial tissue were isolated,flow cytometry was employed to determine the expression of CD11c and CD206,and ELISA to measure the levels of IL-1β,TNF-α,Arg-1,and IL-10 in the macrophages. Results hUC-MSCs had adipogenic and osteogenic differentiation capabilities,and the exosomes were successfully identified.Compared with the negative control group,the miR-204 mimic group showed up-regulated expression of miR-204 in hUC-MSCs and their exosomes(P<0.001,P<0.001).Compared with the sham operation group,the modeling of I/R increased the left ventricular end-diastolic diameter(LVEDD)(P<0.001),left ventricular end-systolic diameter(LVESD)(P<0.001),myocardial injury score(P<0.001),and the levels of IL-1β(P<0.001),TNF-α(P<0.001),and CD11c(P<0.001).Meanwhile,it lowered the left ventricular ejection fraction(LVEF)(P<0.001),left ventricular fractional shortening(LVFS)(P<0.001),Arg-1(P<0.001),IL-10(P<0.001),and CD206(P<0.001).Compared with those in the I/R group,the LVEDD(P<0.001),LVESD(P<0.001),myocardial injury score(P<0.001),and the levels of IL-1β(P<0.001),TNF-α(P=0.010),and CD11c(P<0.001) reduced,while LVEF(P<0.001),LVFS(P<0.001),and the levels of Arg-1(P<0.001),IL-10(P=0.028),and CD206(P=0.022) increased in the hUC-MSC exosomes group.Compared with those in the negative control group,the LVEDD(P<0.001),LVESD(P<0.001),myocardial injury score(P=0.001),and the levels of IL-1β(P=0.048),TNF-α(P<0.001),and CD11c(P=0.007) reduced,while the LVEF(P<0.001),LVFS(P<0.001),and the levels of Arg-1(P<0.001),IL-10(P=0.001),and CD206(P=0.001) increased in the miR-204 mimic group. Conclusion The hUC-MSC exosomes overexpressing miR-204 can inhibit the polarization of macrophages in the I/R mouse model to M1-type and promote the polarization to M2-type.
Animals ; Humans ; Mice ; Disease Models, Animal ; Exosomes/pathology* ; Interleukin-10/metabolism* ; Macrophages ; Mesenchymal Stem Cells ; Mice, Inbred C57BL ; MicroRNAs/genetics* ; Myocardial Reperfusion Injury ; Osteogenesis ; Stroke Volume ; Tumor Necrosis Factor-alpha/metabolism* ; Umbilical Cord/pathology* ; Ventricular Function, Left

This study aimed to explore the mechanism of resveratrol(RES) pretreatment in improving mitochondrial function and alleviating myocardial ischemia-reperfusion(IR) injury by inhibiting stromal interaction molecule 2(STIM2) through microRNA-20 b-5 p(miR-20 b-5 p). Ninety rats were randomly assigned into sham group, IR group, IR+RES(50 mg·kg~(-1) RES) group, IR+RES+antagomir NC(50 mg·kg~(-1) RES+80 mg·kg~(-1) antagomir NC) group, and IR+RES+miR-20 b-5 p antagomir(50 mg·kg~(-1) RES+80 mg·kg~(-1) miR-20 b-5 p antagomir) group, with 18 rats/group. The IR rat model was established by ligation of the left anterior descending coronary artery. Two weeks before the operation, rats in the IR+RES group were intraperitoneally injected with 50 mg·kg~(-1) RES, and those in the sham and IR groups were injected with the same dose of normal saline, once a day. Ultrasonic instrument was used to detect the left ventricular internal diameter at end-diastole(LVIDd) and left ventricular internal diameter at end-systole(LVIDs) of rats in each group. The 2,3,5-triphenyte-trazoliumchloride(TTC) method and hematoxylin-eosin(HE) staining were employed to detect the myocardial infarction area and histopathology, respectively. Real-time quantitative PCR(qRT-PCR) was carried out to detect the expression of miR-20 b-5 p in myocardial tissue. Oxygen glucose deprivation/reoxygenation(OGD/R) was performed to establish an OGD/R model of H9 c2 cardiomyocytes. CCK-8 assay was employed to detect H9 c2 cell viability. H9 c2 cells were assigned into the control group, OGD/R group, OGD/R+RES group(25 μmol·L~(-1)), OGD/R+RES+inhibitor NC group, OGD/R+RES+miR-20 b-5 p inhibitor group, mimic NC group, miR-20 b-5 p mimic group, inhibitor NC group, and miR-20 b-5 p inhibitor group. Flow cytometry was employed to detect cell apoptosis. Western blot was employed to detect the expression of B-cell lymphoma-2(Bcl-2), Bcl-2-associated X protein(Bax), cleaved-cysteine proteinase 3(cleaved-caspase-3), and STIM2 in cells. The mitochondrial membrane potential(MMP) assay kit, reactive oxygen species(ROS) assay kit, and adenosine triphosphate(ATP) assay kit were used to detect the MMP, ROS, and ATP levels, respectively. Dual luciferase reporter gene assay was adopted to verify the targeting relationship between miR-20 b-5 p and STIM2. Compared with the sham group, the modeling of IR increased the myocardial infarction area, LVIDd, LVIDs, and myocardial pathology and down-regulated the expression of miR-20 b-5 p(P<0.05). These changes were alleviated in the IR+RES group(P<0.05). The IR+RES+miR-20 b-5 p antagomir group had higher myocardial infarction area, LVIDd, LVIDs, and myocardial pathology and lower expression of miR-20 b-5 p than the IR+RES group(P<0.05). The OGD/R group had lower viability of H9 c2 cells than the control group(P<0.05) and the OGD/R+RES groups(25, 50, and 100 μmol·L~(-1))(P<0.05). Additionally, the OGD/R group had higher H9 c2 cell apoptosis rate, protein levels of Bax and cleaved caspase-3, and ROS level and lower Bcl-2 protein, MMP, and ATP levels than the control group(P<0.05) and the OGD/R+RES group(P<0.05). The OGD/R+RES+miR-20 b-5 p inhibitor group had higher H9 c2 cell apoptosis rate, protein levels of Bax and cleaved-caspase 3, and ROS level and lower Bcl-2 protein, MMP, and ATP levels than the OGD/R+RES group(P<0.05). miR-20 b-5 p had a targeting relationship with STIM2. The expression of STIM2 was lower in the miR-20 b-5 p mimic group than in the mimic NC group(P<0.05) and lower in the inhibitor NC group than in the miR-20 b-5 p inhibitor group(P<0.05). RES pretreatment can inhibit the expression of STIM2 by promoting the expression of miR-20 b-5 p, thereby improving the function of mitochondria and alleviating myocardial IR damage.
Animals ; Rats ; Adenosine Triphosphate ; Antagomirs/metabolism* ; bcl-2-Associated X Protein/metabolism* ; Caspase 3/metabolism* ; Glucose/metabolism* ; MicroRNAs/metabolism* ; Mitochondria, Heart/drug effects* ; Myocardial Infarction/drug therapy* ; Myocardial Reperfusion Injury/drug therapy* ; Myocytes, Cardiac ; Oxygen/metabolism* ; Proto-Oncogene Proteins c-bcl-2/metabolism* ; Rats, Sprague-Dawley ; Reactive Oxygen Species/metabolism* ; Resveratrol/therapeutic use* ; Stromal Interaction Molecule 2/metabolism*

OBJECTIVE: To examine the effect of Shenmai Injection (SMJ) on ferroptosis during myocardial ischemia reperfusion (I/R) injury in rats and the underlying mechanism. METHODS: A total of 120 SPF-grade adult male SD rats, weighing 220-250 g were randomly divided into different groups according to a random number table. Myocardial I/R model was established by occluding the left anterior descending artery for 30 min followed by 120 min of reperfusion. SMJ was injected intraperitoneally at the onset of 120 min of reperfusion, and erastin (an agonist of ferroptosis), ferrostatin-1 (Fer-1, an inhibitor of ferroptosis) and ML385 (an inhibitor of nuclear factor erythroid-2 related factor 2 (Nrf2)) were administered intraperitoneally separately 30 min before myocardial ischemia as different pretreatments. Cardiac function before ischemia, after ischemia and after reperfusion was analysed. Pathological changes in the myocardium and the ultrastructure of cardiomyocytes were observed, and the myocardial infarction area was measured. Additionally, the concentration of Fe²⁺ in heart tissues and the levels of creatine kinase-MB (CK-MB), troponin I (cTnl), malondialdehyde (MDA) and superoxide dismutase (SOD) in serum were measured using assay kits, and the expressions of Nrf2, glutathione peroxidase 4 (GPX4) and acyl-CoA synthetase long-chain family member 4 (ACSL4) were examined by Western blot. RESULTS: Compared with the sham group, I/R significantly injured heart tissues, as evidenced by the disordered, ruptured and oedematous myocardial fibres; the increases in infarct size, serum CK-MB, cTnI and MDA levels, and myocardial Fe²⁺ concentrations; and the decreases in SOD activity (P<0.05). These results were accompanied by ultrastructural alterations to the mitochondria, increased expression of ACSL4 and inhibited the activation of Nrf2/GPX4 signalling (P<0.05). Compared with I/R group, pretreatment with 9 mL/kg SMJ and 2 mg/kg Fer-1 significantly reduced myocardial I/R injury, Fe²⁺ concentrations and ACSL4 expression and attenuated mitochondrial impairment, while 14 mg/kg erastin exacerbated myocardial I/R injury (P<0.05). In addition, cardioprotection provided by 9 mL/kg SMJ was completely reversed by ML385, as evidenced by the increased myocardial infarct size, CK-MB, cTnI, MDA and Fe²⁺ concentrations, and the decreased SOD activity (P<0.05). CONCLUSIONS Ferroptosis is involved in myocardial I/R injury. Pretreatment with SMJ alleviated myocardial I/R injury by activating Nrf2/GPX4 signalling-mediated ferroptosis, thereby providing a strategy for the prevention and treatment of ischemic heart diseases.
Animals ; Male ; Rats ; Coenzyme A ; Creatine Kinase ; Ferroptosis ; Ligases ; Malondialdehyde ; Myocardial Infarction/drug therapy* ; Myocardial Ischemia/drug therapy* ; Myocardial Reperfusion Injury/pathology* ; Myocytes, Cardiac/metabolism* ; NF-E2-Related Factor 2/metabolism* ; Phospholipid Hydroperoxide Glutathione Peroxidase ; Rats, Sprague-Dawley ; Superoxide Dismutase/metabolism* ; Troponin I