Abstract: AIM:To investigate the role of APPL1 on the protective effect of adiponectin on neonatal cardiomyocytes subjected to hypoxia-reoxygenation (H/R). METHODS: Primary neonatal cardiomyocytes were isolated from the ventricles of 2- to 3-day-old Sprague Dawley (SD) rats by enzymatic digestion and were exposed to hypoxia (940 ml/L N2, 50 ml/L CO2, 10 ml/L O2) for 6 h followed by 12 h reoxygenation (950 ml/L air, 50 ml/L CO2). Cell viability of neonatal cardiomyocytes was measured by MTT assay. Apoptosis of neonatal cardiomyocytes was detected by TUNEL and expression of APPL1 protein was analyzed by Western blot. RESULTS: Cardiomyocyte viability was reduced after H/R (P<0.01 vs. control) and the apoptosis index increased compared with the control group (P<0.01). Administration of adiponectin during reperfusion dramatically attenuated the viability and apoptosis of neonatal cardiomyocytes and upregulated APPL1 expression. To further ascertain the role of APPL1 in adiponectin-induced cardioprotective effect, neonatal cardiomyocytes were transfected with siRNA targeting APPL1, which significantly blunted the anti-apoptotic effect of adiponectin. CONCLUSION: Adiponectin exerts a protective effect on neonatal cardiomyocytes against H/R injury through upregulating APPL1 expression.