Effect of acute isooxic hypercapnia on oxidative activity of systemic neutrophils in endotoxemic rabbits

INTRODUCTION: Whether carbon dioxide (CO(2)) affects systemic oxidative phenomena under conditions of endotoxemia is not sufficiently clarified. The study aimed to assess the impact of moderate acute hypercapnia on the respiratory burst of circulating neutrophils in mechanically ventilated endotoxemic rabbits. MATERIAL AND METHODS: Twenty-four endotoxemic rabbits were mechanically ventilated with standard or CO(2)-enriched gas mixture in order to obtain isooxic hypercapnia. At a baseline point and following 180 min of hypercapnic ventilation, luminol-dependent chemiluminescence (CL) of circulating neutrophils and serum 2-thiobarbituric acid reactive substance (TBARS) concentrations were measured. Throughout the study, leukocyte and neutrophil counts, pH status, circulatory parameters and body temperature were also assessed. RESULTS: Following 180 min of hypercapnic ventilation, opsonized zymosan (OZ)-stimulated neutrophils showed lower CL vs. the control group (p = 0.004). Other parameters studied were not affected. CONCLUSIONS: Short-term isooxic hypercapnia in endotoxemic rabbits preserves circulating neutrophil count pattern and reactive oxygen species (ROS) generation, but it may reduce phagocytosis.