Objective: To investigate the effects of polysaccharides from Rehmanniae Radix(PRR) on oxidative stress and apoptosis of neonatal rat cardiomyocytes impaired by hypoxia-reoxygenation (H/R)

and its potential mechanism. Method: Cardiomyocytes of neonate rat were isolated

cultured for 72 hours

and then randomly divided into six groups:normal control group

model control group

PRR (10

20

40 mg·L-1) treatment groups and SXN (100 mg·L-1)treatment group (n=10). Six hours after the drugs were given

the survival rate was detected by MTT; the activities of aspartate aminotransferase(AST)

creatine kinase(CK) and lactic dehydrogenase(LDH) in culture medium were detected; the activities of superoxide dismutase(SOD) and catalase(CAT) and the content of malondialdehyde(MDA) in cardiomyocytes were determined; the apoptosis was observed by flow cytometry

and the apoptosis rate was calculated; the mRNA expressions of B cell lymphoma/leukemia-2(Bcl-2) and Bcl-2 associated X protein(Bax) were detected by Real-time PCR

and the ratio of Bcl-2/Bax was calculated; the protein expression of Caspase-3 was detected by Western blot. Result: Compared with the model control group

the survival rate of H/R model group was significantly decreased (P<0.01)

the activities of AST

CK

LDH in culture medium were significantly increased (P<0.01)

the activities of SOD and CAT were significantly decreased (P<0.01)

the apoptosis rate was significantly increased (P<0.01)

Bcl-2 and Bax mRNA expressions were significantly increased (P<0.05

P<0.01)

Bcl-2/Bax expression was significantly decreased (P<0.01)

and Caspase-3 protein expression was significantly increased (P<0.01). Compared with the H/R model group

the survival rate of PRR (20

40 mg·L-1) treatment group was significantly increased (P<0.05

P<0.01); the activities of CK

AST

LDH in culture medium were significantly decreased (P<0.05

P<0.01); the activities of SOD

CAT in cardiomyocytes were significantly increased

and the content of MDA was significantly decreased (P<0.05

P<0.01); the apoptosis rate was significantly decreased (P<0.01); the expression of Bcl-2 mRNA was significantly up-regulated

whereas the expression of Bax mRNA and caspase-3 protein were significantly down-regulated

and the ratio of Bcl-2/Bax was significantly increased (P<0.05

P<0.01). Conclusion: PRR had an inhibitive effect on oxidative stress and apoptosis of neonatal rat cardiomyocytes impaired by H/R

which may be related to PRR' capacities of improving the activity of antioxidase

raising the oxygen radical scavenging effect

up-regulating the expression of Bcl-2

down-regulating the expression of Bax

increasing the ratio of Bcl-2/Bax

and inhibiting the expression of Caspase-3 protein.