1. From the Department of Physiology and Pharmacology (J.Z., A.G., J.F.R.P.), Bristol Heart Institute, School of Medical Sciences, University of Bristol, Bristol, United Kingdom; Department of Physiology and Functional Genomics (C.D.-F., M.K.R.), University of Florida, Gainesville; and the Department of Physiology (H.W.), University of Wakayama, Wakayama, Japan. Current address (J.Z.): Department of Integrative Physiology, Health Science Center, University of North Texas, Ft Worth.