Coronary Artery Occlusion Up-regulates The Expressions Of TNF-α In Lungs Of Rats

Objective:The purpose of this study was to investigate changes of TNF-αin lungs and the mechanisms of the changes following acute myocardial ischemia evoked by coronary artery occlusion(CAO) in rats.The intervention effects of pre-treatment with morphine were studied.Methods:The experiments were carried out on male SD rats in two steps.In step one,the rats were randomly devided into two groups:Sham group(group S),with the same scheme of surgery without CAO;Coronary artery occlusion group(group CAO),with the left anterior descending branch of coronary artery occluded under general anaesthesia.Then group S and group CAO were further devided into four subgroups:group 0.5h,group 1h,group 3h and group 6h.Then rats were killed as scheduled,and the samples were collected for IHC,ELISA, In situ hybridization and Real Time RT-PCR.The expressions of TNF-αin lung of the rats were examined.In step two,the timing of highest expression of TNF-αfollowing CAO was chosen for interventional study according to the results of step one experiment.The rats were randomly devided into four groups:Group S(Sham group),Group CAO(Coronary artery occlusion group),Group E-M(epidural mrphine group) and Group E-R(epidural ropivacaine group).Rats were pre-treated with 60μg/kg of Morphine and 1%Ropivacaine 15μl epidurally 15 minutes before CAO.Then rats were killed as scheduled,and the samples were collected for IHC,ELISA,and Real Time RT-PCR.Results:(1) The expressions of TNF-αin lungs were significantly increased after CAO compared with the controls(P＜0.05).The expressions of TNF-αin lungs peaked at 3h of CAO. (2) The expressions of TNF-αdecreased significantly in Group E-M and E-R compared with the CAO Group.Conclusions:(1) Coronary artery occlusion could cause significant increase of TNF-αin lungs of rats.It may demonstrate that acute myocardial ischemia,as a nociceptive stimulus, activated the neural reactions.(2) Rats pre-treated with morphine and ropivacaine epidurally could significantly reduce the expressions of TNF-αin lungs,it may indicate that neural mechanism was involved in the reaction of acute myocardial ischemia,which could be modulated by opioid mechanism.