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Do Oral Contraceptives Change the Ventilatory Response to Group III/IV Skeletal Muscle Afferent Activation?
Author(s) -
Vera Kathryn,
Chantigian Daniel,
Larson Mia,
KellerRoss Manda
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.735.8
Subject(s) - medicine , estrogen , skeletal muscle , menstrual cycle , endocrinology , placebo , respiratory minute volume , hormone , anesthesia , respiratory system , alternative medicine , pathology
Background Group III/IV skeletal muscle afferents increase ventilation (V E ) during exercise. Estrogen has been show to attenuate group III/IV afferent activity. Further, oral contraceptives (OC) lower endogenous estrogen and have been shown to increase V E at rest, although the effect of OCs on V E when group III/IV afferents are activated remains unclear. Objective Determine the influence of OC use on V E in response to activation of group III/IV skeletal muscle afferents during steady state cycling in healthy, young women. Methods Fifteen women (24±2 years, mean ± SD, 8 OC‐users) completed two exercise sessions; once during the low estrogen/low hormone phase (LH, days 1–4 of the menstrual cycle for n‐OC; placebo pill for OC) and once during the high estrogen/high hormone phase (HH, days 10–14 of the menstrual cycle; active hormone pill for OC). Exercise sessions included 25 minutes of steady‐state cycling at a workload of 60W and speed of 65–70rpm. To activate group III/IV afferents, randomized sub‐systolic occlusion at three pressures (20mmHg, 60mmHg and 100 mmHg) were applied bilaterally to the proximal thigh via Hokanson cuffs (DE Hokanson, Inc., Bellevue, WA). After 3 minutes of control (CTL) exercise, cuffs were inflated for two minutes and deflated for five minutes intermittently during exercise. V E , respiratory rate (R R ) and tidal volume (V T ) were continuously monitored (Ultima CardiO 2 , MGC Diagnostics, St. Paul, MN). Results Sub‐systolic circulatory occlusion increased V E from baseline exercise to 100 mmHg (CTL: 27.5±3.5L/min; 100 mmHg: 33.0±3.0 L/min, p<0.001). There were no differences in relative V E (%baseline exercise) following group III/IV afferent activation among OC versus n‐OC users at pressures of 20mmHg (5.9±4.9% vs. 10.2±10.3%, respectively), 60mmHg (15.4±7.5% vs. 12.2±5.4%, respectively) and 100mmHg (22.6±8.2% vs. 19.0±7.8%; respectively, p=0.08). Relative changes in R R and V T (%baseline exercise) also did not differ among OC versus n‐OC users at with increasing cuff occlusion pressures (R R : p=0.39; V T : p=0.37). Conclusions Although OCs lower serum levels of sex hormones, the reduction in endogenous estrogen does not seem to influence the ventilatory response to group III/IV afferent activation in healthy, young women. This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .