OBJECTIVETo investigate extracellular splitting pattern of mitochondria and the depressant effects of CsA on the process and explore the mechanism of post-traumatic SIRS and its therapeutic strategy.

METHODSTen male SD rats with 60 to 70 days age and 240 to 280 g weight were used for mitochondrial isolation. Freshly isolated mitochondria were randomly divided into two groups, which were cultured in blood plasma with or without CsA respectively for 8 h. COX and MDH were assayed by ELISA every 30 min. Meanwhile, Rat macrophage cell line NR8383 were treated as follows, control (group A): cultivation with normal medium; NR8383+CsA co-culture group (group B): culture medium was supplemented with CsA of 10 mmol/L; NR8383+intact mitochondria co-culture group (group C): culture medium was supplemented with intact mitochondria (mtDNA=5 g/ml); NR8383+intact mitochondria+CsA co-culture group (group D): culture medium was supplemented with intact mitochondria (mtDNA=5 μg/ml)and CsA of 10 mmol/L; NR8383+disrupted mitochondria co-culture group (group E): culture medium was supplemented with disrupted mitochondria (mtDNA=5 μg/ml); NR8383+disrupted mitochondria+CsA co-culture group (group F): culture medium was supplemented with disrupted mitochondria (mtDNA=5 μg/ml)and CsA of 10 mmol/L. TNF-α and IL-6 concentrations in supernatant were assessed at 1, 3, 5 h after culture.

RESULTSIn the mitochondria plasma cultures, MDH and COX levels were increased with the time and peaked at about 3 h and 3.5 h; CsA can delay the appearance of peak to 4.5 h. Among different treated groups,there was no significant difference in TNF-α and IL-6 between group A and group B; there was significant difference in TNF-α and IL-6 other groups. After 1 h culture, compared with group C, no significant difference of TNF-α and IL-6 was observed in group D, while TNF-α and IL-6 were significant higher in group E; after 3 h culture, compared with group C, TNF-α and IL-6 were significantly lower in group D, while TNF-α and IL-6 were significantly higher in group E; after 5 h culture, compared with group C, TNF-α and IL-6 were significantly lower in group D, while no significant difference of TNF-α and IL-6 were observed in group E. At each time point, there was no significant difference in TNF-α and IL-6 between group F and group E.

CONCLUSIONMitochondria can split in serum with time, which will further activate macrophages. CsA has depressant effect to mitochondrial splitting on the process and will therefore inhibit the activation of macrophages.