[The changes of the thymocyte mitochondria mediated by nitric oxide in thymocyte apoptosis]

To study the changes of mitochondrial potential (delta psi m) and cardiolipin (CL) content during thymocyte apoptosis mediated by nitric oxide (NO).

SNAP was used as NO's donor to induce thymocyte apoptosis in mice and dexamethasone (DEX) was used as positive control drug. Three experiment groups were set, which were blank control group, SNAP group and DEX group. The ectropion of cell phosphatidylserine (PS) was detected by flow cytometry after stained with FITC-anti-annexin V mAb/PI. The changes of delta psi m and CL content during cell apoptosis were detected by DiOC6(3)/PE-anti-annexin V mAb and NAO/PE-anti-annexin V mAb, respectively.

6 hours after SNAP treatment, the thymocytes exhibited typical cell apoptotic characteristics and crenation appeared in most annexin V-positive cells. In DEX group, the delta psi m decreased and the rate of non-apoptotic cells was significantly higher than that in blank control group, but there was no significant difference between SNAP and control groups. 40%-50% of DiOC6(3)-negative cells in each group had the same size as normal cells. The percentage of the cells with reduced CL content in SNAP group was significantly higher than that in blank control group (P<0.01). Non-apoptotic cells with reduced CL content were not found. In blank control group and SNAP group, percentage of normal-sized cells with reduced CL was (48.32+/-3.96)% and (43.64+/-4.90)%, respectively.

The process of thymocyte apoptosis mediated by NO in mice includes successively PS ectropion, mitochondrial depolarization, CL oxidation and cell crenation. As compared with DEX group, the mitochondrial change mediated by NO is a later event in cell apoptosis.