AIMTo observe the effects of hypercapnia on nuclear factor-kappaB and TNF-alpha in acute lung injury models.

METHODSSix of the twenty-two healthy New Zealand white rabbits were randomly allocated to control group (Group C), the other sixteen rabbits were injected with oleic acid (0.1 ml/kg) intravenously, then were randomized to normocapnic group (Group N, n = 8) versus hypercapnic group (Group H, n = 8). TNF-alpha of serum and bronchoalveolar lavage fluid (BALF) and the expression of nuclear factor-kappaB in the lung were analyzed after three hours' mechanical ventilation.

RESULTSTNF-alpha of serum and bronchoalveolar lavage fluid in Group N and H was significantly higher than that in Group C (P < 0.01), and that of Group N was higher than that of Group H (P < 0.05). The expression of nuclear factor-kappaB in Group H was less than that in Group N by both immunohistochemistry and Western-blot analysis. Peak airway pressure in Group H was significantly lower than that in Group N and the dynamic lung compliance was significantly higher than that in Group N (P < 0.05). PaO2 in Group H was significantly higher than that in Group N (P < 0.05). Histologic damage in Group N was significantly severer than that in Group H.

CONCLUSIONHypercapnia is protective in this in vivo model of ALl. The mechanisms might be associated with the prohibition of nuclear factor-kappaB and then the decreased expression of TNF-alpha by hypercapnia.