1. From the Institut National de la Santé et de la Recherche Médicale (INSERM), Unit 541, Hôpital Lariboisière, Paris, France. Present address for R.H.P.H. is the Department of Pharmacology, Cardiovascular Research Institute Maastricht (CARIM), Maastricht, the Netherlands; for P.M., M.B.-F., F.A.-G. is INSERM Unit 367, Paris, France; and for T.I. is the Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tenn.