1. Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, IA 52242, U.S.A.
2. Veterans Affairs Medical Center, Iowa City, IA 52246, U.S.A.
3. Department of Physiology and Biophysics, ICB-UFMG, Belo Horizonte, MG, Brazil
4. Universidade Federal de Itajubá, Itajubá, MG, Brazil
5. Department of Molecular Physiology & Biophysics, University of Iowa Carver College of Medicine, Iowa City, IA 52242, U.S.A.