Effects of therapeutic hypercapnia on acute pulmonary allograft rejection induced by macrophages in rats / 中华麻醉学杂志

ABSTRACT

Objective To investigate the effects of therapeutic hypercapnia on acute pulmonary allograft rejection induced by macrophages in rats.Methods Twenty-four adult male Wistar rats and 12 adult male Sprague-Dawley rats,weighing 250-280 g,were used in this study.The recipient rats were randomly divided into 3 groups using a random number table (n =6 each)syngraft group (group S),allograft group (group A) and therapeutic hypercapnia group (group H).In group S,Wistar rats served as donors and recipients,while in A and H groups,Sprague-Dawley rats served as donors and Wistar rats served as recipients.Orthotopic left lung transplantation was performed using the cuff technique.After transplantation,the rats inhaled 50％ N2-50％ O2 for 90 min during reperfusion in S and A groups,while in group H the rats inhaled N2-O2-CO2 for 90 min during reperfusion and PaCO2 was maintained at 80-100 mm Hg and O2 concentration in inspired air at 48％-50％ by adjusting the concentrations of the three gases.At 7 days after operation,the arterial blood sample was collected for blood gas analysis and for determination of serum concentrations of tumor necrosis factor α (TNF-α) and interferon γ (IFN-γ)by ELISA.The oxygenation index was calculated.Then the rats were sacrificed,and the transplanted lungs were removed for microscopic examination and for detection of infiltration of macrophages (by immunohistochemistry)and cell apoptosis (by using TUNEL) in lung tissues.The rejection was scored and apoptotic index was calculated.Results Compared with group S,PaCO2,serum concentrations of TNF-α and IFN-γ,rejection score,the number of macrophages and apoptotic index were significantly increased,and oxygenation index was decreased in group A (P ＜ 0.05).Compared with group A,pH value and oxygenation index were significantly increased,and serum concentrations of TNF-α and IFN-γ,rejection score,the number of macrophages and apoptotic index were decreased in group H (P ＜ 0.05).Conclusion Therapeutic hypercapnia can reduce macrophage-induced acute pulmonary allograft rejection possibly through inhibiting the inflammatory responses and cell apoptosis.