1. From the Cardiovascular Research Institute/Medstar Research Institute (M.T.C., P.O., J.-I.K., A.M., N.G., E.C., E.S., A.E.A., W.O.S., K.M.K., L.F.S., A.D.P., N.J.W.), Washington Hospital Center, Washington, DC, and Cardiovascular Research Foundation (G.S.M.), New York, NY. Dr Castagna is currently at the Departmento de Fisiologia e Farmacologia, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil.