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Pregnancy attenuates activity of the baroreceptor reflex
V L Brooks1, R R Quesnell, S R Cumbee
1Department of Physiology, Oregon Health Sciences University, Portland 97201-3098, USA.
Clinical and Experimental Pharmacology & Physiology
|February 1, 1995
Summary
Pregnant animals show impaired blood pressure regulation during hemorrhage due to a weakened baroreceptor reflex. Estrogen alone does not appear to cause this blunted reflex response in pregnancy.
Area of Science:
- Physiology
- Reproductive Biology
- Cardiovascular Regulation
Background:
- Acute blood pressure regulation undergoes significant changes during pregnancy.
- Pregnant animals exhibit diminished capacity to maintain arterial pressure when subjected to hemorrhage compared to non-pregnant counterparts.
Purpose of the Study:
- To investigate the mechanisms underlying impaired acute blood pressure regulation during pregnancy.
- To evaluate the role of the baroreceptor reflex and estrogen in pregnancy-induced cardiovascular adaptations.
Main Methods:
- Review of existing literature on pregnancy-induced cardiovascular changes.
- Comparative analysis of baroreceptor reflex function in pregnant and non-pregnant animals.
- Experimental assessment of estrogen's effect on baroreflex control in non-pregnant rabbits.
Main Results:
- Pregnant animals demonstrate reduced increases in heart rate, renal sympathetic activity, vasopressin, ACTH, and cortisol during hemorrhage.
- The baroreceptor reflex appears less effective in pregnant animals, contributing to their inability to maintain arterial pressure.
- Elevated estrogen levels in non-pregnant rabbits did not attenuate the baroreflex control of renal sympathetic activity.
Conclusions:
- The blunted baroreceptor reflex activity observed during pregnancy is a key factor in the compromised ability to regulate arterial pressure during hemorrhage.
- Estrogen, while altered during pregnancy, does not solely mediate the observed reduction in baroreflex sensitivity.