Objective: To study the effect of Rhodobryum giganteum water extract on cardiocytes injured by hypoxia and explore its mechanism from the perspective of oxidative stress. Method: The injured cardiocyte model induced by hypoxia was established as follows: 3×105-5×105/mL primary cultured neonatal rat cardiomyocytes seeded in 96-well plates were cultured for 48 h in serum-free DMEM/F12

and then placed in hypoxia (37 ℃

94%N2

1%O2

5%CO2) to incubate for another 24 h. 1

2

3

4

5 g·L-1 water extract of R. giganteum was added to cultivated injuried cardiocytes

and after 24 h

the activity of the cells was carefully determined by A value with MTT method. Activity of super oxide dismutase (SOD)

malonaldehyde (MDA)

lactate dehydrogenase (LDH) and creatine kinase (CK) in medium was assayed by automatic biochemistry anaIyzer. Result: The A values indicated that 3

4 g·L-1 R. giganteum water extract groups increased activity of the cells significantly compared with the model group (0.498±0.012) (P<0.05

P<0.01). And it could reduce LDH

CK activity and MDA levels and increase SOD activity in medium

and 3 g·L-1 group was much better than other dose groups. Conclusion: Water extract of R.giganteum has protective effect on cardiocytes injured by hypoxia

the mechanism may be related to inhibiting oxidative stress.