@article{a5ee3606062546fbb14aac7297f5d451,
title = "Heart period variability during estrogen exposure and withdrawal in female rats",
abstract = "Heart period, heart period variability, and an estimate of vagal tone were evaluated during estrogen exposure and withdrawal in ovariectomized, freely moving female rats. Spectral analysis was used to quantify the respiratory component of heart period variability ({\^V}), which has been found to be sensitive to alterations of vagal tone to the heart. During estrogen withdrawal, {\^V} decreased significantly and was accompanied by a decrease in heart period. There were no significant differences in heart period or {\^V} between the experimental (estrogen) group and the control (no estrogen) group during estrogen exposure. Total heart period variability did not differ significantly from controls during estrogen withdrawal but it did exhibit an increase during estrogen exposure. In this experiment {\^V} appeared to be more sensitive to changes in estrogen levels than total heart period variability. These data suggest that decreases in cardiac vagal tone and heart rate occur during estrogen withdrawal.",
keywords = "Estrogen exposure and withdrawal, Freely moving rats, Heart period, Heart period variability, Menopause, Respiratory sinus arrhythmia, Spectral analysis, Vagal tone estimate",
author = "McCabe, {Philip M.} and Porges, {Stephen W.} and Carter, {Carol Sue}",
note = "Funding Information: It is possible to non-invasively estimate the vagal tone to the heart by quantifying a component of heart rate variability, respiratory sinus arrhythmia (RSA). Physiologically, RSA is a naturally occurring arrhythmia of the sinoatrial node which exhibits a periodicity similar to respiration. An increase in heart rate is observed during inspiration and upon expiration heart rate decreases. Regardless of the mechanism through which respiration exerts its influence on heart rate, RSA is mediated mainly through the vagus \[2,8\]. In anesthetized dogs, it has been demonstrated that the ampli, tude of RSA is highly correlated with parasympathetic control of the heart \[8\]. However, in unanesthetized preparations this measure would be confounded by movement and other non-respirational influences on heart rate. Porges \[16\]h as proposed that spectral analysis may provide an accurate method of assessing vagal tone even when the heart rate pattern is also influenced through non-vagal athways. The spectral component of heart rate variability, , has been found to parallel shifts in vagal tone \[13,16\]. The purpose of the present study was to examine in an animal model a possible role for the ovarian hormone, estrogen, in the regulation of the heart. Specifically, in the rat, heart rate patterns were evaluated with spectral analysis. By inspecting the respiratory component of heart period varia- 1Send reprint requests to Stephen W. Porges, Department of Psychology, University of Illinois, Champaign, IL 61820. We would like to thank Lathrop Taylor for her valuable assistance during this study. This research was supported by Biomedical Research Support Grant BRSG, RR-07030, Research Scientist Development Award K02-MH-00054 awarded to Stephen W. Porges, and RIAS Training Grant NSF SER 76-18255 and NIMH Training Grant MH 15128.",
year = "1981",
month = mar,
doi = "10.1016/0031-9384(81)90184-0",
language = "English (US)",
volume = "26",
pages = "535--538",
journal = "Physiology and Behavior",
issn = "0031-9384",
publisher = "Elsevier Inc.",
number = "3",
}