1. From the Department of Physiology (N.P.R., H.L., J.R.C.P., B.T.E., J.W.P., H.J.J., A.M.G., D.L.M.), and Human and Molecular Genetics Center (B.T.E., J.W.P., H.J.J., A.M.G.), Medical College of Wisconsin, Milwaukee; and Department of Medicine, Medical College of Wisconsin, Zablocki Veterans Affairs Medical Center, Milwaukee (E.P.C.).