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Cardiac sympathetic activity during rat pregnancy
W R Cohen1, L H Galen, M Vega-Rich
1Department of Obstetrics and Gynecology, Albert Einstein College of Medicine, Bronx, NY.
Metabolism: Clinical and Experimental
|August 1, 1988
Summary
Cardiac sympathetic nervous system activity significantly increases during late rat pregnancy, particularly in the heart. However, this heightened activity is not observed in brown adipose tissue, suggesting localized changes during gestation.
Area of Science:
- Physiology
- Neuroendocrinology
- Reproductive Biology
Background:
- Pregnancy involves significant physiological adaptations, including alterations in the autonomic nervous system.
- Understanding changes in sympathetic nervous system (SNS) activity during gestation is crucial for maternal and fetal health.
- Previous research has not fully elucidated the specific impact of pregnancy on cardiac and brown adipose tissue SNS activity.
Purpose of the Study:
- To investigate the turnover of norepinephrine (NE) in the heart and interscapular brown adipose tissue (BAT) of pregnant rats.
- To assess 24-hour urinary excretion of catecholamines (NE, epinephrine, dopamine) during pregnancy.
- To determine if cardiac and BAT SNS activity changes progressively during gestation and if adrenal medullary function is affected.
Main Methods:
- Injected tracer [3H]norepinephrine ([3H]NE) to measure fractional NE turnover in heart and interscapular BAT of virgin, 10-day, and 20-day pregnant rats.
- Collected 24-hour urine samples serially from six pregnant rats and virgin controls.
- Quantified urinary excretion of norepinephrine (NE), epinephrine (E), and dopamine (D) using established methods.
Main Results:
- Fractional [3H]NE turnover in the heart was significantly higher (87-92%) in 20-day pregnant rats compared to virgin controls.
- No significant difference in NE turnover was observed in the heart at 10 days of pregnancy or in interscapular BAT at any gestational stage.
- Urinary NE excretion progressively increased during late pregnancy, reaching 2.6-fold higher than controls at term; E and D excretion remained unchanged.
Conclusions:
- Cardiac sympathetic nervous system activity is significantly increased during the later stages of rat pregnancy.
- The observed increase in sympathetic activity during pregnancy appears to be localized to the heart, not global, as indicated by unchanged NE turnover in BAT.
- Urinary catecholamine excretion patterns support increased cardiac sympathetic activity in late gestation, with no evidence of altered adrenal medullary function.