1. From the Departments of Cardiovascular Biology (G.B., T.W., R.L., D.A., L.B., S.N., H.G., J.B., C.K., L.M., M.P., C.D.), Medicinal Chemistry (M.M., A.S., C.L., P.P.), and Laboratory Animal Resources (B.O.), Rhone-Poulenc Rorer, Collegeville, Pa, and Drug Metabolism (K.P.), Rhone-Poulenc Rorer, Dagenham, Essex, UK.