1. From the Division of Nephrology, Department of Medicine (W.-Z.Y., K.A., P.-X.W., P.W.S.), Nephrology Research and Training Center (W.-Z.Y., K.A., P.-X.W., P.W.S.), and Department of Physiology and Biophysics (P.W.S.), University of Alabama at Birmingham, Birmingham, Ala; Department of Veterans Affairs Medical Center (P.W.S.), Birmingham, Ala.