Heat stress due to high environmental temperatures lowers blood pressure in autonomic failure patients. The mechanisms underlying this phenomenon are not fully understood but it could be associated with 2 factors: First, heart stress is more likely to increase core temperature in this patient population because heat dissipation is impaired due to inability to sweat. Second, autonomic failure patients lack the compensatory sympathetic splanchnic vasoconstriction and tachycardia that normally maintain blood pressure in response to heat stress in healthy subjects. We hypothesize, therefore, that even moderate levels of local heat stress will lower blood pressure in patients with autonomic failure and supine hypertension. We propose a pilot study to evaluate the effect of local (abdominal) heat stress on blood pressure in autonomic failure patients, something that has not been previously done, and to assess its potential use in the treatment of supine hypertension