title: Effects of the ovarian cycle on sympathetic neural outflow during static exercise.
abstract: We compared reflex responses to static handgrip at 30% maximal voluntary contraction (MVC) in 10 women (mean age 24.1 +/- 1.7 yr) during two phases of their ovarian cycle: the menstrual phase (days 1-4) and the follicular phase (days 10-12). Changes in muscle sympathetic nerve activity (MSNA; microneurography) in response to static exercise were greater during the menstrual compared with follicular phase (phase effect P = 0.01). Levels of estrogen were less during the menstrual phase (75 +/- 5.5 vs. 116 +/- 9.6 pg/ml, days 1-4 vs. days 10-12; P = 0.002). Generated tension did not explain differences in MSNA responses (MVC: 29.3 +/- 1.3 vs. 28.2 +/- 1.5 kg, days 1-4 vs. days 10-12; P = 0.13). In a group of experiments with the use of 31P-NMR spectroscopy, no phase effect was observed for H+ and H2PO-4 concentrations (n = 5). During an ischemic rhythmic handgrip paradigm (20% MVC), a phase effect was not observed for MSNA or H+ or H2PO-4 concentrations, suggesting that blood flow was necessary for the expression of the cycle-related effect. The present studies suggest that, during static handgrip exercise, MSNA is increased during the menstrual compared with the follicular phase of the ovarian cycle.
authors.affiliation: Section of Cardiology, Department of Health Evaluation Sciences, The Pennsylvania State University, The Milton S. Hershey Medical Center, Hershey PA, 17033, USA. settinge@med.hmc.psghs.edu
authors.forename: S M
authors.initials: SM
authors.lastname: Ettinger
authors.forename: D H
authors.initials: DH
authors.lastname: Silber
authors.forename: K S
authors.initials: KS
authors.lastname: Gray
authors.forename: M B
authors.initials: MB
authors.lastname: Smith
authors.forename: Q X
authors.initials: QX
authors.lastname: Yang
authors.forename: A R
authors.initials: AR
authors.lastname: Kunselman
authors.forename: L I
authors.initials: LI
authors.lastname: Sinoway
mesh_terms: D000328:Adult; D004958:Estradiol / Q000097:blood; D004970:Estrone / Q000097:blood; D015444:Exercise / Q000502:physiology*; D005260:Female; D005498:Follicular Phase / Q000502:physiology; D018737:Hand Strength / Q000502:physiology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007511:Ischemia / Q000503:physiopathology; D009682:Magnetic Resonance Spectroscopy; D008597:Menstrual Cycle / Q000502:physiology*; D008598:Menstruation / Q000502:physiology; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000294:innervation / Q000502:physiology; D010756:Phosphoric Acids / Q000378:metabolism; D012018:Reflex / Q000502:physiology; D013564:Sympathetic Nervous System / Q000502:physiology*
chemical_list: D010756:Phosphoric Acids; D004970:Estrone; D004958:Estradiol