[Protective effect of endogenous carbon monoxide on organs during septic shock in rat and its mechanisms].

Objective: To study the protective effect of endogenous carbon monoxide (CO) on lung and liver during septic shock in rat and its mechanism.

Methods: Septic shock model was replicated by cecal ligation and puncture (CLP). Ninety-six rats were randomly divided into sham operation group, CLP group, CLP+ hemin (Hm) group and CLP+zinc protoporphyrin (ZnPP) group. The carboxyhemoglobin (COHb) levels of in-flowing pulmonary blood (IPB) and out-going pulmonary blood (OPB) were determined at 2, 4 and 6 hours after treatments. Malondialdehyde (MDA) contents and superoxide dismutase (SOD) activities in the lung, liver and blood were also determined. Pathological changes in lung and liver were examined with light microscope, and immunohistochemical technique was used for analysis of heme oxygenase-1 (HO-1) protein expression and distribution in lung and liver.

Results: Compared with sham operation group, the COHb level in OPB and IPB as well as MDA contents of lung, liver and blood significantly increased in CLP group, while the SOD activities significantly decreased at different time points (P<0.05 or P<0.01), and the pathological changes and expressions of HO-1 in two tissues were more marked. However, in CLP+Hm group the results of MDA, SOD activities and pathological changes were reversed. The content of COHb increased compared to those of CLP group. Immunohistochemical studies showed that there were more HO-1 positive deposits in CLP+Hm group than those in CLP group.

Conclusion: Increase in endogenous CO may play a protective role in lung and liver during septic shock.