Effects of naloxone on pneumocyte apoptosis during pulmonary ischemia reperfusion injury

Objective To investigate the effects of naloxone (Na) on pneumocyte apoptosis and expression of heme oxygenase-1 (HO-1) during ischemia reperfusion injury of lung in rats. Method Forty-two male Sprague-Dawley rats were made models of ischemia reperfusion injury of unilateral lung, and were randomly( random number) divided into three groups: sham operation group (Sh group), ischemia reperfusion group (IR group) and naloxone group (Na group). The hilus of lung was clamped for 45 minutes and the clamp was taken off to build the I/R model. After 3-6 hours reperfusion, naloxone in dose of 1 mg/kg was injected intra-peritoneally in rats of Na group. The rate of cell apoptosis in lung tissue was detected with the way of Annexin-V-PI in flow cy-tometer. The wet to dry weight ratio (W/D) of lung tissue was measured. The expression of HO-1 in lung was measured by using RT-PCR and the ultra-structure change of lung tissue was observed under electron microscope. Results The rate of pneumocyte apoptosis and W/D ratio of lung tissue were significantly higher in IR group than in Sh group (P < 0.01), and the rate of pneumocyte apoptosis and W/D ratio of lung tissue were negatively correlated with the expression of HO-1 mRNA in lung tissue. Compared with IR group, the rate of cell apoptosis and W/D ratio were lower and the expression of HO-1 mRNA was higher in Na group (P < 0.01). The ultra- structure changes of lung tissue were lessened in Na group than in IR group. Conclusions During early period of lung IR injury, HO-1 induced by naloxone can inhibit the cellular apoptosis and protect the lung tissue. Key words: Rat;  Lung;  Reperfusion injury;  Naloxone;  HO-1;  Apoptosis;  RT-PCR;  Annexin-V-PI