Neurohumoral and endothelial responses to heated water-based exercise in resistant hypertensive patients

Background: The neurohumoral and endothelial responses to the blood pressure (BP) lowering effects of heated water-based exercise (HEx) in resistant hypertension (HT) patients remain undefined. Methods and Results: We investigated these in 44 true resistant HT patients (age 53.3±0.9 years, mean ± SEM). They were randomized and allocated to 2 groups, 28 to a HEx training protocol, which consisted of callisthenic exercises and walking in a heated pool for 1 h, three times weekly for 12 weeks and 16 patients to a control group maintaining their habitual activities. Measurements made before and after 12 weeks of HEx included clinic and 24-h BP, plasma levels of nitric oxide, endothelin-1, aldosterone, renin, norepinephrine and epinephrine, as well as peak VO₂, and endothelial function (reactive hyperemia). After 12 weeks of HEx patients showed a significant decrease in clinic and 24-h systolic and diastolic BPs. Concomitantly, nitric oxide increased significantly (from 25±8 to 75±24 μmol/L, P<0.01), while endothelin-1 (from 41±5 to 26±3 pg/mL), renin (from 35±4 to 3.4±1 ng/mL/h), and norepinephrine (from 720±54 to 306±35 pg/mL) decreased significantly (P<0.01). Plasma aldosterone also tended to decrease, although not significantly (from 101±9 to 76±4 pg/mL, P=NS). Peak VO₂ increased significantly after HEx (P<0.01), while endothelial function was unchanged. No significant change was detected in the control group. Conclusions: The BP-lowering effects of HEx in resistant HT patients were accompanied by a significant reduction in the marked neurohumoral activation characterizing this clinical condition.