1. From the Cardiovascular Research Center and Department of Physiology (H.O., H.S., H.N., S.D., S.E.), Temple University School of Medicine, Philadelphia, Pa; Department of Biochemistry (G.D.F.), Vanderbilt University School of Medicine, Nashville, Tenn; and the Department of Biomedical Sciences (E.D.M.), Division of Cardiovascular Biology, Meharry Medical College, Nashville, Tenn.