Abstract: Objective To study the expression changes of apelin and its receptor APJ at kidney tissue of rats chronically exposed to hypoxia. Methods Twenty male Sprague-Dawley rats were randomly divided into control group and 4-week hypoxia group. The levels of blood urea nitrogen (BUN), serum creatinine (Scr) and renal tissue hydroxyproline were measured. The protein level of apelin in the kidney was measured by radioimmunoassay. The mRNA expressions of apelin and APJ in kidney tissue were determined by reverse transcription polymerase chain reaction. Results ① The content of hydroxyproline in hypoxia group was 37.31%(P＜0.01) higher than that in control group ,while there were no significant differences of Scr and BUN between the two groups.② The expressions of apelin and APJ mRNA in kidney tissue of hypoxia group were higher than those of control group (P＜0.0).③ The protein level of apelin in kidney of hypoxia rats also was obviously higher than that of control ones. Conclusion The increased protein and gene expressions of apelin and APJ in kidney tissue of rats chronically exposed to hypoxia might be an important factor in the development of renal interstitial fibrosis.

Key words: Apelin, Receptor, Hypoxia, Fibrosis, Renal interstitium, Rat