Abstract: Objective:To observe the protective effects of apelin-13 on on the expression of APJ (putative receptor protein related to the angiotensin receptor AT1)and Akt1/2 in ischemia/reperfusion injury rat heart in virtro Methods Langendorff device was used to perfuse isolated rat heart with constant flow. The ischemia/reperfusion models of rat heart in vitro were made through stopping and reperfusion of the KH fluid to the heart；observing the change of maximal rate of the pressure increase(+dp/dtmax) and maximal rate of the pressure decrease(-dp/dtmax) of left ventricle in rat heart . RT-PCR were used to assay the expression of APJmRNA in rat heart, Western blotting were used to assay Akt1/2 protein in rat heart. Results The groups given apelin-13 had higher ±LVdp /dtmax（p<0.01）; and resulted in hyper-expression of Akt1/2 protein (p<0.05), while the expression of APJmRNA were up regulated in IR group(p<0.05). Conclusion: Apelin-13 can resist the functional impairment in rat heart caused by ischemia/reperfusion injury, and the protecting effects of apelin-13 may involved in up regulated expression of APJ in rat heart, and the APJ might cause up regulated expression of Akt1/2 which would do good to I/R injury heart.

Key words: ischemia/reperfusion injury, Myocardium, apelin