BACKGROUND: To explore the role of the MAPK signaling pathway in the cardiomyocyte apoptosis of mice with post-infarction heart failure (HF). METHODS: Mice were divided into sham and myocardial infarction (MI) groups. Before surgery, the MI group was divided into SB203580 and PBS subgroups. A post-infarction HF model was established by ligating the left anterior descending coronary artery. Ventricular dilatation and cardiac function were observed by small animal echocardiography. The growth of

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... phy. The growth of primary cardiomyocytes was observed under an inverted phase contrast microscope. The mRNA and protein expressions of endoplasmic reticulum stress (ERS) markers, GRP78 and CHOP, were detected by qRT-PCR and immunofl uorescence assay, respectively. RESULTS: The MI group had enlarged left ventricle and decreased cardiac function. GRP78 and CHOP protein expressions in myocardial tissues, especially those of SB203580 subgroup, signifi cantly increased (p < 0.05). The expressions of p-JNK and cleaved caspase 12 proteins, especially those of SB203580 subgroup, were signifi cantly up-regulated. Cardiomyocytes of MI group were signifi cantly more prone to apoptosis (p < 0.05), with SB203580 subgroup being more obvious. CONCLUSION: MI was accompanied by ERS, probably involving the MAPK signaling pathway. SB203580, a specifi c inhibitor of this pathway, can relieve cardiomyocyte apoptosis and protect the myocardium by suppressing such stress (Tab. 3, Fig. 7 , Ref. 20). Text in PDF www.elis.sk.