Objective:This study evaluated myocardium damage under the irradiation of ultrasound combined with homemade nitric oxide (NO) microbubbles. Furthermore,we intended to investigate the stromal cell-derived factor-1(SDF-1) expression in rat myocardium after the intervention of ultrasound combined with NO microbubbles. Methods:Thirty-two rats were divided into four groups randomly. Ultrasound (1MHz,1W/cm2) was applied to the anterior chest for ten minutes in group one (US+NOMB),group two (US+MB) and group three (US+PBS),group four was set for contrast. Four rats were sacrificed in each group four hours later and myocardium was harvested for HE staining. Serum was also collected for myocardial enzyme testing. One week later,all rats were sacrificed,and RT-PCR and western blotting were performed for testing SDF-1 expression. Results:HE staining showed that there were no significant differences in pairwise comparison. Creatine kinase and lactic dehydrogenase were higher in the group one and the group two than those in the group three and group four (P < 0.05),but there was no significant difference between the group one and the group two (P > 0.05). Troponin I was lower in the group one than that in group two,but higher than those in the group three and group four (P < 0.05). RT-PCR and Western blotting demonstrated that the expression of SDF-1 was higher in the group one than that in the group two,group three and group four,and all the P values were less than 0.05. Conclusion:NO microbubble,as a novel microbubble,is safe for rat myocardium. Moreover,it can induce a higher SDF-1 expression than common lipidic microbubbles,which shows great potential for stem cells homing.