AIM: To explore the mechanism underlying inducible nitric oxide (NO) caused injury of endothelial cells during inflammation. METHODS: The activity of iso-enzymes of NO synthase (NOS), NO level and iNOS expression were examined using NADPH method, Griess reaction and RT-PCR, respectively. Furthermore, the lactate dehydrogenase (LDH) release rate, malondialdehyde (MDA) content were also measured. RESULTS:Co-administration of cytokines (TNF-? 5?10 5 U/L, IL-1? 2?10 5 U/L, INF-? 2?10 5 U/L) and LPS (10 mg/L) caused an obvious increase in NOS activity, NO levels (about two-fold) and a significant injury of the cells. At the same time, a significant increase in iNOS mRNA was also detected. Wheareas, treatment of the cells separately with cytokines or LPS for 24 h had no significant effect on NOS activity and NO level in cell lysates, however, it caused a significant increase in LDH release and MDA content. Also, the effect of cytokines and LPS on cell viability was concentration-and time-dependent. L-NMMA, a inhibitor of NOS, can suppress inducible NO production and protect cells against NO induced injury. CONCLUSION:Co-administration of cytokines (TNF-?, IL-1? and INF-?) and LPS significant activated iNOS and NO production which, in turn, induced oxidative reaction in endothelial cells.

AIM: To explore the effect of aspirin on inducible nitric oxide synthesis and gene expression under inflammation in endothelial cells. METHODS: Using NADPH, Griess methods and RT-PCR, the activity of isozymes of NO synthase (NOS), nitric oxide (NO) level, and iNOS mRNA expression were examined respectively. Also, the lactate dehydrogenase (LDH) release rate, malondialdehyde (MDA) content and cell viability were measured. RESULTS: Aspirin (3 mmol/L) reduced inducible NO production and NOS activity(P

AIM: To explore the regulatory effects of ferritin expression and intracellular iron change on aspirin resistance to oxidative damage in endothelial cells. METHODS: Using ELISA to measure the levels of ferritin expression under different aspirin concentrations, in the presence of iron cheltor desferioxamine and add to FeCl 3. Then using RNA-protein bandshift assay and RT-PCR to examine the activation of IRP and the expression of IRP 2 mRNA onaspirin induced ferritin formation. RESULTS: Aspirin at low concentration (0.1mmol/L) induced significant increase in ferritin expression in a concentration-dependent fashion up to 25% over basal levels. Aspirin induced cytoprotection from H 2O 2 damage increased significantly following ferritin formation in endothelial cells.However, in the presence of iron chelator desferrioxamine, aspirin enhanced ferritin synthesis was abrogated with a 3 fold increase in the activity of IRP and significant increase in IRP 2 mRNA level. In contrast, FeCl 3 and aspirin both increased the level of induced ferritin synthesis with significant decrease in IRP activity and IRP 2 mRNA level. CONCLUSION: The effect of aspirin induced ferritin synthesis on resistance to oxidative damage in endothelium was operated through down-regulating IRP activation and IRP 2 mRNA level.