Pancuronium bromide, a non-depolarizing muscle relaxant which promotes apoptosis of blood lymphocytes in vitro

Background: Several compounds used in anesthesia practice have demonstrated to impair immune function and to influence the process of apoptotic death in T cell population following surgical trauma. We designed this study to test in vitro the impact of neuromuscular blocker, such as pancuronium, at clinically relevant concentration on lymphocyte apoptosis, death factor expression and mitochondrial function. Methods: Following isolation, lymphocytes were incubated with pancuronium bromide at a clinically relevant concentration (0.136 mumol l(-1)) for 3 h at 37C in a 5% carbon-dioxide-humidified atmosphere and the frequency of apoptotic lymphocytes was then measured. We also investigated crucial steps in the apoptotic process, including Fas/Fas ligand ( FasL) phenotype, intracellular expression of the interleukin-1beta-converting enzyme ( ICE) p20, mitochondrial membrane potential (DeltaPsim), generation of mitochondrial reactive oxygen species, and glutathione (GSH) levels. Control experiments were performed incubating cells in the complete culture medium added with the dilution medium of the drug without addition of the drug. Results: Expression of Fas, FasL and ICEp20 was six-fold, fourfold, and five-fold increased, respectively, among pancuronium-treated lymphocytes with respect to control cultures ( P = 0.0001). The percentage of cells exhibiting either dissipation of mitochondrial membrane potential or increased production of reactive oxygen species was seven-fold increased following exposure to pancuronium compared with untreated lymphocytes ( P = 0.0001). These findings were associated with a decrease in GSH level. In addition, the frequency of apoptotic cells was 10-fold greater among lymphocytes cultured in the presence of the drug with respect to control cultures. ( P = 0.0001). Conclusion: Our data suggest an apoptogenic effect of pancuronium in vitro at clinically relevant concentration on peripheral blood lymphocytes. This could be implicated in the transient immune suppression following a surgical operation.