1. Department of Special Medicine, Medical College, Qingdao University, Qingdao, Shandong 266071, P.R. China
2. Department of Nephrology, Medical College, Qingdao University, Qingdao, Shandong 266071, P.R. China
3. Department of Nephrology, Affiliated Hospital of Qingdao University, Qingdao, Shandong 266003, P.R. China
4. Department of Physiology, Medical College, Qingdao University, Qingdao, Shandong 266071, P.R. China