1 Divisions of Clinical Pharmacology, Department of Medicine (K.E., A.W., S.P., M.S., S.K., A.D., C.A.S., I.B.), Vanderbilt University Medical Center, Nashville, TN.
2 Autonomic Dysfunction Center (K.E., A.W., S.Y.P., A.D., C.A.S., I.B.), Vanderbilt University Medical Center, Nashville, TN.
3 and Vanderbilt Eye Institute (K.M.J.), Vanderbilt University Medical Center, Nashville, TN.