Objective To observe the sensitivity of myocardium to ischemia/reperfusion (I/R) injury in mechanical trauma rats.Methods The mechanical trauma was established by Noble-Collip drum in the rats that were completely randomized into five groups:sham trauma group,trauma group,sham trauma and sham surgery group,sham trauma and I/R group,trauma and I/R group.The rats were subjected to 30 minutes of ischemia and one hour of reperfusion one week after trauma.The left ventricular systolic pressure (LVSP) and the left ventricular maximum rate of pressure rise and fall ( ± dp/dtmax ) were recorded with BL-410 biological signal recording and analysis system.The levels of serum creatine kinase isoenzyme MB (CK-MB) and cardiac troponinⅠ (cTnI) were detected by double antibody sandwich ABC-ELISA technique.At the end of reperfusion,the heart was excised and stained with Evan' s blue dye and triphenyltetrazolium chloride (TTC) to measure the infarct region with Image-Pro Plus 6.0 image analysis software.Results Compared with the sham traumatic I/R group,the cardiac function in vivo was significantly decreased in the traumatic I/R group ( P ＜ 0.01 ).While the serum CK-MB [ (4 960 ± 588 ) ng/ml:(2 925 ± 426) ng/ml,P ＜ 0.01 ],cTnI [ ( 18.10 ± 3.06 ) ng/ml:( 6.67 ±1.57 ) ng/ml,P ＜ 0.01 ] levels and myocardial infarct size [ ( 36.70 ± 7.42 ) ％:( 22.27 ± 4.54 ) ％,P＜0.01] were obviously higher in the traumatic I/R group compared with the sham traumatic I/R group.Conclusion Mechanical trauma increases the sensitivity of myocardium to I/R injury in rats.