Activation of Sonic hedgehog signaling in ventricular cardiomyocytes exerts DNA protection against hypoxia / 中国药理学通报

Aim To investigate the protective roles of sonic hedgehog( Shh) signaling pathway in hypoxia-in-duced DNA damage with the neonatal rat cardiomyo-cytes. Methods The hypoxia model on neonatal car-diomyocytes was established with one to two days old Sprague Dawley rats by deprivation of oxygen and glu-cose ( OGD) . After pretreated with Shh pathway ago-nist SAG1.3 or antagonist GANT61, the survival rates of cardiomyocytes were assayed by MTT after OGD 6 hours or 12 hours. The protein levels of Shh pathway, phosphorylated histone H2AX at serine 139 (γH2AX), phosphorylated ATM (p-ATM), phospho-rylated p53 ( p-p53 ) , cleaved-caspase-3, Bcl-2 and Bax were detected by Western blot. The γH2AX foci was detected by immunofluorescence. Results Com-pared to control group, the protein expression of γH2AX, p-ATM, cleaved-caspase-3, p-p53 in OGD cardiomyocytes significantly increased, and Bcl-2/Bax ratio proportionally decreased. Particularly, the ex-pression of γH2AX, p-ATM was highest at OGD 6 h, and then gradually declined after OGD 12 h. After SAG1.3 pretreatment, the expression of γH2AX, p-ATM, cleaved-caspase-3 and p-p53 dramatically de-creased and the Bcl2/Bax ratio increased in OGD 6 h or OGD 12 h cardiomyocytes. On the contrary, in GANT61 pretreatment group, the expression of γH2AX, p-ATM, cleaved-caspase-3 and p-p53 signifi-cantly increased and the Bcl-2/Bax ratio decreased compared to the OGD 6 h or OGD 12 h cardiomyo-cytes. Conclusion The activation of Shh pathway protects cardiomyocytes against hypoxia-induced apop-tosis through inhibition of DNA damage.

Reactive oxygen species mediate cultured neonatal rat cardiac myocyte hypertrophy induced by endothelin-1 / 生理学报

The effects of endothelin-1 (ET-1) and other drugs on the reactive oxygen species (ROS) generation and cardiomyocyte hypertrophy were examined in experiments on the cultured neonatal rat cardiomyocytes. The role of ROS on neonatal rat cardiomyocyte hypertrophy induced by ET-1 was studied and the relationship of PKC activation and ROS generation was investigated. The level of intracellular ROS was measured by the ROS-specific probe 2',7'-dichlorofluorescin diacetate (DCF-DA). Cardiomyocyte hypertrophy was determined by the RNA content, the total protein of cells and the cell surface area. The results are as follows. The fluorescence intensity of intracellular DCF-DA increased by 77% in cultured neonatal rat cardiac myocytes treated with ET-1 (10 nmol/L) vs control group. Compared with control group, the fluorescence intensity of intracellular PI, protein content and cell surface area increased by 128%, 87% and 151% respectively (all P<0.01) in cardiac myocytes treated with ET-1 (10 nmol/L). ABT-627, CC, or CAT inhibited the ET-1-induced increase in fluorescence intensity of intracellular DCF-DA by 62%,60% and 51% respectively (all P<0.01), and also attenuated the cardiac hypertrophy. The fluorescence intensity of intracellular DCF-DA increased by 74% (P<0.01) in myocytes treated with PMA (1 micromol/L) vs control group. Therefore, in the course of cardiomyocyte hypertrophy, ET-1 increases intracellular ROS in the cultured neonatal rat cardiac myocytes and inhibits cardiomyocyte hypertrophy induced by ROS. The ET(A) and PKC activation mediate the ROS production and cardiomyocyte hypertrophy induced by ET-1. ROS is necessary in the ET-1-induced cardiomyocyte hypertrophy.