[The anti-apoptotic effects of N-acetylcysteine in neonatal rat cardiomyocytes underwent hypoxia-reoxygenation injury].

OBJECTIVE

To evaluate the effects of N-acetylcysteine (NAC) on hypoxia-reoxygenation (H/R) injury induced apoptosis in neonatal rat cardiomyocytes.

METHODS

Neonatal rat cardiomyocytes were cultured for 48 h and then randomized into control group, H/R group and H/R + NAC group. Cardiomyocytes underwent hypoxia for 6 h, reoxygenation for 72 h in the absence (H/R group) or presence (H/R + NAC group) of NAC (100 micromol/L). Cell viability was assayed with trypan blue staining. Early stage of apoptosis was detected by flow cytometry with Annexin V, late stage of apoptosis was assessed by TUNEL staining. ROS in culture medium was assayed by Image-iT(TM) LIVE green reactive oxygen species detection kit.bcl2 and bax mRNA levels were determined by real-time quantitative PCR (RT-PCR). bcl2, bax, p38 and pp38 protein levels were measured by Western blot.

RESULTS

The percentage of viable cardiomyocytes (93.5%, 74.9%, 89.9%) was significantly reduced while percentage of early stage of apoptotic cardiomyocytes (6.5%, 25.2% and 11.1%) and late stage of apoptotic cardiomyocytes (3.5%, 33.5% and 13.5%) were significantly increased in H/R group compared to control group and these changes could be largely reversed by NAC (all P < 0.01). Significantly increased ROS generation in H/R group could also be attenuated by NAC (P < 0.01). The band density ratio of pp38 and p38 was significantly upregulated in H/R group (13.4 vs. 3.89), the mRNA and protein expressions of bcl2 were significantly lower and bax expressions were significantly higher in H/R group than those in control group and these changes could also be attenuated by NAC.

CONCLUSIONS

NAC significantly reduced apoptosis through inhibiting the phosphorylation of p38 signal pathway.