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Full-Text Articles in Social and Behavioral Sciences

Effects Of Gender And Hypovolemia On Sympathetic Neural Responses To Orthostatic Stress, Qi Fu, Sarah Witkowski, Kazunobu Okazaki, Benjamin D. Levine Jul 2005

Effects Of Gender And Hypovolemia On Sympathetic Neural Responses To Orthostatic Stress, Qi Fu, Sarah Witkowski, Kazunobu Okazaki, Benjamin D. Levine

Exercise and Sport Studies: Faculty Publications

We tested the hypothesis that women have blunted sympathetic neural responses to orthostatic stress compared with men, which may be elicited under hypovolemic conditions. Muscle sympathetic nerve activity (MSNA) and hemodynamics were measured in eight healthy young women and seven men in supine position and during 6 min of 60° head-up tilt (HUT) under normovolemic and hypovolemic conditions (randomly), with ∼4-wk interval. Acute hypovolemia was produced by diuretic (furosemide) administration ∼2 h before testing. Orthostatic tolerance was determined by progressive lower body negative pressure to presyncope. We found that furosemide produced an ∼13% reduction in plasma volume, causing a similar …


Persistent Sympathetic Activation During Chronic Antihypertensive Therapy, Qi Fu, Rong Zhang, Sarah Witkowski, Armin Arbab-Zadeh, Anand Prasad, Kazunobu Okazaki, Benjamin D. Levine Jan 2005

Persistent Sympathetic Activation During Chronic Antihypertensive Therapy, Qi Fu, Rong Zhang, Sarah Witkowski, Armin Arbab-Zadeh, Anand Prasad, Kazunobu Okazaki, Benjamin D. Levine

Exercise and Sport Studies: Faculty Publications

Previous studies have demonstrated that antihypertensive treatment resets baroreflex control of heart rate (HR) and increases cardiac vagal baroreflex sensitivity. However, it is uncertain whether baroreflex control of muscle sympathetic nerve activity (MSNA) also resets after treatment. We tested the hypothesis that chronic antihypertensive therapy alters baroreflex regulation of MSNA in patients with untreated moderate hypertension. Seven newly diagnosed patients with systolic blood pressure (BP) of 159 5 mm Hg (mean SE) and diastolic BP of 103 4 mm Hg were studied before and after 1 to 2 weeks ´ and 3 months (chronic) of antihypertensive treatment with losartan– hydrochlorothiazide …