1. From the the Water and Salt Research Center, Institute of Physiology and Biophysics (V.V.M., A.R., D.M.B.B., S.G., A.K.H., E.V.B., H.A.P., C.A., H.N.), University of Aarhus, Denmark; Department of Physiology (H.G.), University of Göteborg, Sweden; and the Laboratoire de Biologie Moléculaire et Cellulaire du Développement (S.G.), Université Pierre et Marie Curie, Paris, France.