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Longitudinal Assessment Of The Modulatory Effect Of Estrogen On Blood Pressure And Cardiac Autonomic Activity In Female Rats
Author(s) -
ElMas Mahmoud M,
AbdelRahman Abdel A
Publication year - 2009
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.23.1_supplement.577.8
Subject(s) - baroreflex , medicine , endocrinology , ovariectomized rat , blood pressure , heart rate , estrogen , hemodynamics , autonomic nervous system , heart rate variability
Reported findings on the effect of ovarian hormones on hemodynamic variability are contradictory. In this study we employed radiotelemetric hemodynamic monitoring to investigate the long‐term effect of estrogen depletion and repletion on cardiac autonomic control and baroreflex sensitivity (BRS). Blood pressure (BP), heart rate (HR), and +dP/dt max (index of myocardial contractility) were monitored in sham‐operated (SO), ovariectomized (OVX), and estrogen‐treated OVX (OVXE 2 ) rats for 16 weeks. Cardiovascular autonomic control was assessed by frequency analysis of interbeat intervals (IBI) and systolic BP (SBP). Compared with SO, OVX rats exhibited sustained reductions in dP/dt max despite similar BP and HR. High‐frequency (HF, 0.75‐3 Hz), but not low‐frequency (LF, 0.25‐0.75 Hz), bands of IBI were reduced in OVX rats, suggesting attenuated cardiac vagal activity. OVX increased IBI LF/HF ratio, indicating increased sympathetic dominance. Indexα, spectral index of BRS, was reduced in OVX rats. E 2 replacement decreased BP and HR and reversed the effects of OVX on dP/dt max and cardiac autonomic activity. LF oscillations of SBP were reduced in OVXE 2 rats, highlighting a reduction in vascular sympathetic tone. Conclusions long‐term estrogen therapy rectifies the detrimental cardiovascular and baroreflex influences caused by depletion of ovarian hormones. Supported by Grant R01 AA014441 from NIAAA.