Abstract: Objective To investigate the effect of adipokine Apelin on vascular calcification of rats with chronic kidney disease. Methods The rats were randomly divided into Control group (given normal diet), Model group (given 0.75% adenine diet to induce chronic kidney disease and aortic calcification) , Apelin-treated group ( given 0.75% adenine diet and subcutaneous infusion of Apelin-13 20μg/kg daily) and Apelin-treated normal group (given normal diet and subcutaneous infusion of Apelin-13 20μg/kg daily) , n=10 separately. The rats were sacrificed at six weeks and the serum levels of Ca, P, urea nitrogen and creatinine were analyzed using an autoanalyzer. ELISA was used to evaluate the plasma level of Apelin. RT-qPCR was used to detect the mRNA expression of APJ and Pit-1 in aorta. Immunohistochemistry was used to visualize the distribution of Runx2 and osteoprotegerin in aorta. Von Kossa staining was performed to evaluate aortic calcification. Results At week 6, compared with Control group, serum urea nitrogen and creatinine concentrations increased significantly（P<0.01）, serum Ca decreased, serum P increased（P<0.01）, with decrease of serum Apelin （P<0.01）and mRNA expression of APJ in aorta（P<0.05）, increased expression of Runx2, osteoprotegerin , obvious calcification and increased mRNA expression of Pit-1 in aorta in Model group（P<0.05）. Compared with Model group, Apelin-treated group improved hyperphosphatemia（P<0.05）, normalized the plasma level of Apelin and APJ mRNA expression（P<0.05）, attenuated the expression of Runx2, osteoprotegerin, calcification lesion and Pit-1 mRNA expression（P<0.05）. Conclusion Apelin/APJ is able to ameliorate vascular calcification of CKD rats.

Key words: Apelin, Pit-1, Hyperphosphatemia, Vascular calcification, Chronic kidney disease