Muscle sympathetic nerve activity and hemodynamic responses to venous distension: does sex play a role?

Abstract

Peripheral venous distension mechanically stimulates type III/IV sensory fibers in veins and evokes pressor and sympathoexcitatory reflex responses in humans. As young females have reduced venous compliance, smaller increases in arterial pressure to type III/IV sensory fibers activation and impaired sympathetic transduction, we tested the hypothesis that pressor and sympathoexcitatory responses to venous distension may be attenuated in women compared to men. Mean arterial pressure (MAP, photoplethysmography), heart rate (HR), stroke volume (SV, Modelflow), cardiac output (CO = HR x SV), muscle sympathetic nerve activity (MSNA), femoral artery blood flow and conductance (FABF and FACT, Doppler ultrasound) were quantified in 8 males (27 ± 4 yrs.) and 9 females (28 ± 4 yrs.) before (CON) during (INF) and after (Post‐INF) a local infusion of normal saline (5% of the forearm volume) through a retrograde catheter inserted into an antecubital vein of the forearm, to which venous drainage and arterial supply had been occluded. MAP increased during and after infusion in both groups (vs. CON, p ≤ 0.05) but women showed a smaller pressor response in the Post‐INF period (Δ+7.2 ± 2.0 vs. men Δ+18.3 ± 3.9 mmHg, p = 0.019). MSNA increased and FACT decreased similarly in both groups (vs. CON, p ≤ 0.05) at Post‐INF. While HR changes were similar, increases in SV (Δ+20.4 ± 8.6 vs. Δ+2.6 ± 2.7 mL, p = 0.05) and CO (Δ+0.84 ± 0.17 vs. Δ+0.34 ± 0.10 L/min, p = 0.024) were greater in men than women. Therefore, these findings indicate that venous distension evokes a smaller pressor response in young women due to attenuated cardiac adjustments rather than to reduced venous compliance or sympathetic transduction. Support or Funding Information Support: CNPq, CAPES, FAPERJ This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Trajectory Analysis of Orthostatic Hypotension in Parkinson’s Disease: Results From Parkinson’s Progression Markers Initiative Cohort

“…We also found that male sex was one of the predictors of increasing ΔSBP. This finding in patients with PD is distinct relative to the general population, where it is reported that the incidence of OH is higher in women than men ( Fedorowski et al, 2009 ), due to higher estrogen levels, a more active parasympathetic system, lower sympathetic activity, and an attenuated venous distension reflex in women ( Cheng et al, 2011 ; Mansur et al, 2019 ). Estrogen decreases BP by lowering the plasma renin activity, whereas testosterone decreases BP by increasing the plasma renin activity ( Reckelhoff et al, 1998 ).…”

Impact of whole body passive heat stress and arterial shear rate modification on radial artery function in young men

“…We assume that forearm metabolic rate was not different between trials and as such do not expect differences in downstream tissue oxygen to have occurred and contributed to the vascular responses observed. We cannot discount the possibility that wrist cuff inflation may have evoked venous distension and a reflex increase in vasoconstrictor sympathetic nerve activity (23,30).…”

GABAA receptors modulate sympathetic vasomotor outflow and the pressor response to skeletal muscle metaboreflex activation in humans

“…; Mansur et al . ). Briefly, a unipolar tungsten microelectrode was inserted percutaneously through the intact skin and positioned into muscle nerve fascicles of the peroneal nerve of the right leg at the fibular head, and a reference electrode was placed s.c. 2–3 cm distal.…”

“…Multiunit recordings of postganglionic MSNA were obtained as described previously (Fisher et al 2015a;Fernandes et al 2018;Vianna et al 2018;Mansur et al 2019). Briefly, a unipolar tungsten microelectrode was inserted percutaneously through the intact skin and positioned into muscle nerve fascicles of the peroneal nerve of the right leg at the fibular head, and a reference electrode was placed s.c. 2-3 cm distal.…”