RESUMO
The aim of the present study was to investigate the effect of prostaglandin (PG) E1 on hypoxia/re-oxygenation (H/R) apoptosis and the expression of bcl-2 and bax in cultured neonatal rat cardiomyocytes. The H/R model was made using the first generation of cultured neonatal rat cardiomyocytes. Hypoxia/re-oxygenation apoptosis was studied by electron microscopy and agarose gel electrophoresis. The percentage of apoptotic cells was measured by terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick end-labeling (TUNEL). The expression of bcl-2 and bax was detected by in situ hybridization and immunohistochemical staining. Most cells of the H/R group tested by electron microscopy showed cytoplasmic concentration, nuclear chromatin condensation and margination. Prostaglandin E1 (5, 15 and 45 microg/L) relieved the injury. The results of DNA electrophoresis in the H/R group showed a typical DNA ladder and the DNA ladder decreased gradually corresponding with increasing doses of PGE1. The TUNEL staining showed that the total number of apoptotic cells in the H/R group was much more than that in the PGE1 (45 microg/L) group. The results of in situ hybridization and immunohistochemical staining showed that the bcl-2 content in the H/R group was lower than that in the control group; bax content showed the reverse. Compared with the H/R group, bcl-2 content was significantly higher in the PGE1 (5, 15 and 45 microg/L) groups. However, bax content in the PGE1 (5, 15 and 45 microg/L) groups was significantly lower than that in the H/R group. 6. In conclusion, H/R injury can induce cardiomyocyte apoptosis. Prostaglandin E1 obviously has anti-apoptotic effects on cardiomyocytes and the mechanisms probably involve the inhibition of bax expression and increased expression of bcl-2.
Assuntos
Alprostadil/farmacologia , Apoptose/fisiologia , Hipóxia/patologia , Miócitos Cardíacos/fisiologia , Oxigênio/fisiologia , Animais , Animais Recém-Nascidos , Apoptose/efeitos dos fármacos , Células Cultivadas , DNA/biossíntese , DNA/genética , Eletroforese em Gel de Poliacrilamida , Genes bcl-2/genética , Hipóxia/tratamento farmacológico , Imuno-Histoquímica , Hibridização In Situ , Marcação In Situ das Extremidades Cortadas , Microscopia Eletrônica , Miócitos Cardíacos/efeitos dos fármacos , Miócitos Cardíacos/ultraestrutura , RNA Mensageiro/biossíntese , RNA Mensageiro/genética , Ratos , Proteína X Associada a bcl-2/biossíntese , Proteína X Associada a bcl-2/genéticaRESUMO
AIM: To investigate the effect of G(alphaq/11) signaling pathway and ATP-sensitive potassium channels (K(ATP) channels) on prostaglandin E1 (PGE1) induced early and delay-preconditioning protection in rat hearts. METHODS: Two series of experiments were performed in Wistar rat hearts. In the first series of experiment, all rats were pretreated with PGE1 40 min or 23 h 20 min before the experiment. Ischemia-reperfusion injury was induced by 30 min coronary artery occlusion followed by 90 min reperfusion. Hemodynamics, infarct size, and scores of ventricular arrhythmias were measured. The expression of G(alphaq/11) protein in the heart was measured by Western blot analysis in the second series. RESULTS: Preconditioning with PGE1 (25 microg/kg) markedly reduced infarct size, left ventricular end-diastolic pressure, and scores of ventricular arrhythmia. The effect of PGE1 was significantly attenuated by glibenclamide (1 mg/kg, ip), a nonselective K(ATP) channel inhibitor. PGE1 caused a significant increase in the expression of G(alphaq/11) protein. CONCLUSION: Activations of G(alphaq/11) signal pathway and K(ATP) channel played significant roles in the cardioprotection of PGE1 preconditioning in rat heart and might be an important mechanism of signal transduction pathway during the PGE1 preconditioning.
