1. From the Department of Anesthesiology (P.R.P., H.-J.W., A.M.S.), University of Nebraska Medical Center, Omaha.
2. Department of Cellular and Integrative Physiology (I.H.Z., A.M.S., H-J.W.), University of Nebraska Medical Center, Omaha.
3. Division of Cardiovascular Medicine (Y.S.C.), University of Nebraska Medical Center, Omaha.