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Muscle Sympathetic Nerve Activity and Hemodynamic Responses to Venous Distension: Does Sex Play a Role?
Author(s) -
Mansur Daniel,
Campos Monique O,
Mattos João D,
Paiva Adrielle CS,
Videira Rogério,
Macefield Vaughan,
Nóbrega Antonio CL,
Fernandes Igor Alexandre
Publication year - 2019
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2019.33.1_supplement.561.1
Subject(s) - medicine , distension , heart rate , anesthesia , blood pressure , hemodynamics , mean arterial pressure , baroreflex , reflex , sympathetic nervous system , plethysmograph , femoral artery , forearm , cardiology , anatomy
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 .