Objective： To investigate the morphological changes of the cultured SAN cells in ischemia model and the protective effects of captopril on the SAN cells with ischemic injury. Methods: One hundred and fifty SD rats of 4 d old were used to develop primary cell culture of SAN cells. Then, living cells which included the cells in normal growing condition and in ischemic model were observed. In addition, living cells of SAN were fixed and stained with HE, and observed by light microscopy and transmission electromicroscopy(TEM). Results: The vitality, the morphologic characteristic and architecture of cultured SAN cells were slightly injured at 60 min,obviously injured at 90 min and seriously injured at 120 min following ischemia, whereas in the group treated with captopril the injuries were found to be significantly relieved. Conclusion：The ischemic injuries of cultured SAN cells in ischemia model were intensively developed with prolonged ischemia and the obvious protective effects of captopril on cultured SAN cells in ischemic model were observed.