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Effects of gender and the menstrual cycle on sympathetic and vagal responses to a Valsalva maneuver in humans
Author(s) -
Fu Qi,
Shook Robin,
Okazaki Kazunobu,
Shibata Shigeki,
Hastings Jeff,
Conner Colin,
Palmer M. Dean,
Levine Benjamin D.
Publication year - 2006
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.20.4.a735
Subject(s) - baroreflex , valsalva maneuver , medicine , heart rate , blood pressure , microneurography , menstrual cycle , supine position , bradycardia , autonomic nervous system , sympathetic nervous system , anesthesia , cardiology , hormone
We tested the hypothesis that sympathetic and vagal responses to a Valsalva maneuver (VM) are different between the genders, and can be affected by the menstrual cycle in women. Ten healthy young males and seven pre‐menopausal females were studied. All females had regular menstrual cycles and were tested twice: once during the early follicular and once during the luteal phase with the order counterbalanced. The VM (40mmHg, 20sec) was performed supine, muscle sympathetic nerve activity (MSNA), blood pressure (BP), and heart rate were recorded. Sympathetic baroreflex sensitivity was assessed by relating all MSNA bursts occurring during the 20‐sec straining period to the maximum fall of systolic BP (SBP). Cardiovagal baroreflex sensitivity was assessed using the linear correlation between SBP and R‐R interval during the early phase II (decreasing BP, hypotensive stimulus) and phase IV (increasing BP, hypertensive stimulus). We found that sympathetic baroreflex sensitivity was similar between the genders and between the menstrual phases. Cardiovagal baroreflex sensitivity during decreasing BP was comparable between the genders or menstrual phase. Interestingly, cardiovagal baroreflex sensitivity during increasing BP was significantly greater in males than in females ( P =0.003), while the sensitivity was similar between the menstrual phases. These results suggest that gender but not the menstrual cycle can influence cardiovagal baroreflex‐mediated bradycardia during a hypertensive stimulus. However, sympathetic and cardiovagal baroreflex responses during hypotensive stimulus are similar between the genders and are not affected by the menstrual cycle.