Effects of cardiopulmonary bypass on lung nuclear factor-kappa B activity, cytokine release, and pulmonary function in dogs

Abstract

<em>Objective(s):</em> To study the effect of cardiopulmonary bypass (CPB) on nuclear factor-kappa B (NF-кB) and cytokine expression and pulmonary function in dogs. <br/><em>Materials and Methods:</em> Twelve male mongrel dogs were divided into a methylprednisolone group (group M) and a control group (group C). All animals underwent aortic and right atrial catheterization under general anesthesia. Changes in pulmonary function and hemodynamics were monitored and the injured site was histologically evaluated. <br/><em>Results:</em> The activity of NF-кB and myeloperoxidase (MPO), levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, and IL-8, and the wet/dry (W/D) weight ratio were significantly higher after CPB than before CPB in both groups (P<0.01), with the lower values in group M than in group C, at different time points (P<0.01). Histological evaluation revealed neutrophilic infiltration and thickening of the alveolar interstitium in both groups; however, the degree of pathological changes was significantly lower in group M than in group C. The alveolar–arterial O2 tension difference (PA-aDO2) was significantly higher after CPB than before CBP (P<0.01), and lower in group M than in group C (P<0.01). The pulmonary compliance after removal of the aortic clamp obviously decreased in group C (P<0.05), with no significant change in group M. <br/><em>Conclusion:</em> CPB can significantly enhance the activation of NF-кB in lung tissues and increase the expression of inflammatory cytokines, thus inducing lung injury. Methylprednisolone can inhibit the NF-кB activation, thus inhibiting the release of cytokines and protecting the lung function.