Effects Of Dexmedetomidine Pretreatment On Cardiac Toxicity Threshold Of Rats Induced By Ropivacaine

Objective：To investigate the effects of dexmedetomidinepretreatment oncardiac toxicity threshold of rats induced byropivacaine.Methods：Twenty eight Wistar rats, aged8-12weeks and weighing250-350g, were randomly allocated to four groups of increasing concentrationof dexmedetomidine infused via a femoral vein over10min and monitoredwith ECG and MAP. The groups were: R (0μg/kg); D1(5μg/kg); D2(10μg/kg)and D3(15μg/kg). The control group R was administered0.5ml of normalsaline. Ten minutes after infusing dexmedetomidine, ropivacaine1%wasinfused at1ml/h via the femoral vein in all four groups until an adverse cardiacevent occurred. The following statistics were then recorded: dose ofropivacaine, duration of infusing ropivacaine and plasma concentration ofropivacaine.Results：Compared with group R, experiment groups had higher dose ofropivacaine(P＜0.05), longer duration of infusing ropivacaine(P＜0.05) andhigher plasma concentration of ropivacaine(P＜0.05). However, there was nosignificant difference among experiment groups in above statistic parameters(P＞0.05).Conclusion：Dexmedetomidine pretreatment increases cardiac toxicitythreshold of rats induced by ropivacaine, which is not associated with the doseof dexmedetomidine pretreatment.