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Autonomic function and baroreflex sensitivity during a normal ovulatory cycle in humans.
L Guasti1, P Grimoldi, L T Mainardi
1Chair of Internal Medicine, University of Insubria, Varese, Italy.
Acta Cardiologica
|October 8, 1999
Summary
Autonomic function shows changes during the ovulatory cycle, with increased sympathetic activity in the luteal phase. However, baroreflex sensitivity remains largely unaffected by menstrual cycle phases.
Area of Science:
- Cardiovascular Physiology
- Autonomic Nervous System Function
- Reproductive Endocrinology
Background:
- Autonomic function variations during the ovulatory cycle are not well understood.
- The impact of menstrual cycle phases on baroreflex sensitivity is largely unknown.
Purpose of the Study:
- To investigate heart rate variability and baroreceptor sensitivity during different phases of the normal ovulatory cycle.
- To determine if baroreflex sensitivity changes across the menstrual cycle.
Main Methods:
- Evaluated heart rate variability using power spectrum analysis.
- Assessed baroreceptor sensitivity via the alpha-low frequency coefficient.
- Studied 13 young women with regular menses during two cycle phases (follicular and luteal).
Main Results:
- The low frequency/high frequency ratio, indicative of sympathovagal balance, was significantly higher in the luteal phase (p < 0.05).
- Normalized low frequency power increased, while normalized high frequency power decreased in the luteal phase (p < 0.05).
- No statistically significant difference was observed in baroreceptor sensitivity (alpha-low frequency coefficient) between the two cycle phases.
Conclusions:
- Power spectrum analysis suggests autonomic function is influenced by the ovulatory cycle, with increased sympathetic activation in the luteal phase.
- Baroreceptor function appears to be minimally affected by the different phases of the menstrual cycle.