Effects of sevoflurane postconditioning on myocardial ischemia-reperfusion-induced oncosis of cardiomyocytes in rats: relationship with mitochondrial permeability transition pore

Objective To investigate the effects of sevoflurane postconditioning on myocardial ischemiareperfusion (I/R)-induced oncosis of cardiomyocytes and the role of mitochondrial permeability transition pore (MPTP) in it.Methods Sixty male Sprague-Dawley rats,aged 3 months,weighing 280-360 g,were randomly divided into 5 groups (n =12 each):sham operation group (group S),group I/R,sevoflurane postconditioning group (group SP),sevoflurane postconditioning + atractyloside group (group SP + ATR) and atractyloside group (group ATR).Myocardial ischemia was induced by 30 min occlusion of left anterior descending branch (LAD) of coronary artery followed by 2 h reperfusion.2.5 ％ sevoflurane was inhaled for 5 min starting from 27 min of ischemia until 2 min after beginning of reperfusion in SP and SP + ATR groups,while 33 ％ oxygen was inhaled in the other groups.In SP + ATR and ATR groups,atractyloside 5 mg/kg was injected via the internal jugular vein at 15 min before ischemia.HR and systolic pressure were monitored and recorded and rate-pressure product (RPP) was calculated.At the end of reperfusion,the rats were sacrificed and the hearts removed for determination of myocardial infarct size.The myocardial ultrastrncture was observed by electron microscopy.The expression of Porimin (Pro-oncosis receptor inducing membrane injury) was measured by Western blot.Myocardial nicotinamide adenine dinucleotide (NAD+) content was determined by spectrophotometry.Results Compared with group S,the myocardial infarct size was significantly enlarged,the expression of Porimin was up-regulated,and NAD+ content and RPP were decreased in the other four groups (P ＜ 0.05).Compared with groups I/R and SP + ATR,the infarct size was significantly decreased,the expression of Porimin was down-regulated,and NAD+ content was increased in group SP (P ＜ 0.05),and no significant change was found in the indices mentioned above in group ATR (P ＞0.05).Conclusion Sevoflurane postconditioning can mitigate myocardial I/R injury by inhibiting MPTP opening and reducing oncosis of cardiomyocytes. Key words: Anesthetics, inhalation ;  Myocardial reperfusion injury ;  Cell death