The effects of dexmedetomidine preconditioning on aged rat heart of ischaemia reperfusion injury.

To assess the effect of dexmedetomidine on myocardial ischemia reperfusion injury in vivo aged rat heart. 40 healthy male, 20month aged, 350-400g Sprague-Dawley rats. Rats were divided into four groups randomly(n=10): group of ischemic preconditioning(IP group), group of Sham(CS group), group of dexmedetomidine(DP group), Ischemia-reperfusion injury group(IR group). The date of HR and ±dp/dtmax were detected before and after the occur of ischemia reperfusion. Superoxide dismutase (SOD) and malondialdehyde (MDA) activity were recorded; myocardial infarct size was calculated at the end of reperfusion. HR in each group decreased after thoracotomy. Compared with CS group, the HR in IR group reduced significantly (P<0.05). After given dexmedetomidine, HR in the DP group began to decrease significantly. Left heart function in IR group compared with the CS group showed that a statistically reduce of left ventricular function happened in IR group. ±dp/dtmax of the IR groups compared with the CS group were increased. SOD activity reduced and MDA in myocardial tissue homogenates increased in IR group (P<0.05); SOD activity in DP group compared with IR group deduced, MDA increased (P<0.05). Dexmedetomidine preconditioning can effectively reduce ischemia reperfusion injury of the aged rat in vivo, have a protective effect on aged rat heart.