Effects Of Dexmedetomidine On Neutrophil Apoptosis In Peripheral Blood In Patients With Coronary Artery Bypass Grafting Under Cardiopulmonary Bypass

Objective:To investigate effects of dexmedetomidine on neutrophil apoptosis in peripheral blood in patients with coronary artery bypass grafting under cardiopulmonary bypass.Methods:Forty American Society of Anesthesiologists physical statusⅡorⅢpatients of both sexes,of New York Heart AssociationⅡorⅢ,aged52～68 yr,scheduled for elective coronary artery bypass grafting under cardiopulmonary bypass,were randomly divided into 2 groups（n=20 each）using a random number table:control group（group C）and dexmedetomidine group（group D）,after anesthesia induced intubation,dexmedetomidine1.0μg/kg（initial dose）was given over more than 10 min,followed by continuous infusion at 0.5μg·kg^-1·h^-1until the end of operation.The equal volume of normal saline was given instead of dexmedetomidine in group C.Before CPB（T1）,30min after begainning of CPB（T2）,immediately after the end of CPB（T3）and 24 h after the end of CPB（T4）blood samples were collected for determination of plasma IL-6 concentrations using flow cytometry,the neutrophil apoptosis rate and the expression of Bcl-2 and p-stat3 in neutrophils.Results:Compared with the baseline value at T1,the PMN apoptosis rate were decreased at T2-4 than that of at T1 in two groups,and reached its lowest value at T3.The plasma IL-6 levels and the percentage of Bcl-2 and p-stat3positive expression in PMN were increased at T2-4 than that of at T1 in two groups,and reached its highest value at T3（P<0.05）.Compared with group C,the PMN apoptosis rate in group D were increased at T2-4,the plasma IL-6levels and the percentage of Bcl-2 and p-stat3 positive expression in PMN in group D at T2-4 were decreased（P<0.05）.In group C and D,the PMN apoptosis rate was negatively correlated with CPB duration;in group C and D,the plasma IL-6 levels and the percentage of Bcl-2 and p-stat3 positive expression in PMN were negatively correlated with the PMN apoptosis rate at T3（P<0.05）;in group C and D,the percentage of Bcl-2 positive expression in PMN were positive correlated with the percentage of p-stat3 positive expression in PMN at T3（P<0.05）.Conclusion:Dexmedetomidine attenuated the inhibition of neutrophil apoptosis in patients with coronary artery bypass grafting under cardiopulmonary bypass,which might be related to inhibition of JAK/STAT pathway activation and down-regulation of Bcl-2 expression.