Peripheral venous distension mechanically stimulates type III/IV sensory fibers in veins and evokes pressor and sympathoexcitatory reflex responses in humans. As young women have reduced venous compliance and impaired sympathetic transduc-tion, we tested the hypothesis that pressor and sympathoexcitatory responses to venous distension may be attenuated in women compared with men. Mean arterial pressure (photoplethysmography), heart rate (HR), stroke volume (SV; Modelflow), cardiac output (CO = HR X SV), muscle sympathetic nerve activity (MSNA), femoral artery blood flow, and femoral artery conductance (Doppler ultrasound) were quantified in eight men (27 ± 4 yr) and nine women (28 ± 4 yr) before control (CON), during (INF), and immediately after (post-INF) a local infusion of saline 5 of the total forearm volume (30 ml/min); the infusion time was 2 ± I and 1 ± 1 min (P = 0.0001) for men and women, respectively through a retrograde catheter inserted into an antecubital vein, to which venous drainage and arterial supply had been occluded. Mean arterial pressure increased during and after infusion in both groups (vs. the CON group, P < 0.05), but women showed a smaller pressor response in the post-INF period (A + 7.2 ± 2.0 vs. A+ 18.3 ± 3.9 mmHg in men, P = 0.019).
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