1. From the Department of Medical Physiology (C.Z., T.W.H., W.W., L.K.), College of Medicine, Texas A&M University System Health Science Center, College Station, Tex; the Michael E. DeBakey Institute (M.W.M., T.W.F., M.M.M.), Department of Small Animal Medicine and Surgery, College of Veterinary Medicine, Texas A&M University, College Station, Tex; and the Department of Biomedical Engineering (J.D.H.), Dwight Look College of Engineering, Texas A&M University, College Station, Tex.