patients with autonomic failure and supine hypertension from all races, who are in the hospital participating in the study "the evaluation and treatment of autonomic failure" (irb# 000814).

supine hypertension, defined as a systolic blood pressure >150 mm hg or diastolic blood pressure > 90 mm hg.

males and females, between 18-85yr.

provide written informed consent to participate in the study and understand that they may withdraw their consent at any time without prejudice to their future medical care.

pregnant women.

high-risk patients (e.g. heart failure, symptomatic coronary artery disease, liver impairment, history of stroke or myocardial infarction).

history of serious allergies or asthma.

in the investigator's opinion, have clinically significant abnormalities on clinical, mental examination or laboratory testing.

all medical students.