Effect of isoflurane preconditioning on cell apoptosis during renal ischemia-reperfusion in rats

Objective To evaluate the effect of isoflurane preconditioning on cell apoptosis during renal ischemia-reperfusion (I/R) in rats. Methods Thirty male Sprague-Dawley rats, aged 12-14 weeks, weighing 300-320 g, were randomly divided into 3 groups (n = 10 each) using a random number table: sham operation group (group S); I/R group; isoflurane preconditioning plus I/R group (group Iso+ I/R). The rats were anesthetized with intraperitoneal pentobarbital sodium 30 mg/kg.To establish the model of renal I/R injury, the right kidney was removed, and the left renal pedicle was occluded for 30 min with atraumatic mini-clamp for 30 min, followed by 2 h reperfusion.In Iso+ I/R group, 1.5% isoflurane was inhaled for 1 h, followed by 30 min of washout before I/R.In S and I/R groups only oxygen 2 L/min was inhaled for 1 h. Arterial blood samples were taken at 2 h of reperfusion to determine the concentrations of serum creatinine (Cr), blood urea nitrogen (BUN) and cystatin C (CysC). The animals were then sacrificed, and left kidneys were sampled for determination of the cell apoptosis (by TUNEL), expression of p53, Bax and Bcl-2 mRNA (using real-time fluorescent quantitative PCR), and expression of Bax, Bcl-2, and caspase-3 (by Western blot analysis). The Bcl-2/Bax ratio was calculated. Results Compared with group S, the serum Cr, BUN, and CysC concentrations were significantly increased, the Bcl-2/Bax ratio was decreased, Bcl-2 mRNA, Bax mRNA, Bcl-2, Bax and caspase-3 expression was up-regulated, and AI was increased in group I/R.Compared with group I/R, the serum Cr, BUN, and CysC concentrations were significantly decreased, the Bcl-2/Bax ratio was increased, Bcl-2 mRNA, Bax mRNA, Bax and caspase-3 expression was down-regulated, and AI was decreased in group Iso+ I/R.There was no significant difference in p53 mRNA expression among the three groups. Conclusion Regulating the balance between Bcl-2 and Bax and inhibiting apoptosis in kidney cells are involved in the mechanism by which isoflurane preconditioning reduces renal I/R injury in rats. Key words: Isoflurane; Ischemic preconditioning; Apoptosis; Kidney; Reperfusion injury