| Abstract | Previous studies demonstrated the protective effects of estrogen administration in models of cardiovascular disease. However, there is a discrepancy between these data and those from the recent clinical trials with hormone replacement therapy in menopausal women. One possible explanation for the divergent results is the addition of progestin to the hormone regimen in the Women's Health Initiative and the Heart and Estrogen/Progestin Replacement Study trials. The aim of the present study was to examine the effects of a combination of 17beta-estradiol (E(2), 20 microg) and medroxyprogesterone acetate (MPA, 80 microg) on infarct size in New Zealand White rabbits. Infarct size as a percentage of the area at risk was significantly reduced by administration of E(2) 30 min before induction of myocardial ischemia compared with vehicle (19.5 +/- 3.1 vs. 55.7 +/- 2.6%, P < 0.001). However, E(2) + MPA failed to elicit a reduction in infarct size (52.5 +/- 4.6%), and MPA had no effect (50.8 +/- 2.6%). E(2) also reduced serum levels of cardiac troponin I, immune complex deposition in myocardial tissue, activation of the complement system, and lipid peroxidation. All these effects were reversed by MPA. The results suggest that MPA antagonizes the infarct-sparing effects of E(2), possibly through modulation of the immune response after ischemia and reperfusion. |
| Authors | Erin A Booth, Benedict R Lucchesi
(Affiliation: Department of Pharmacology, University of Michigan Medical School, 1301C Medical Science Research Bldg. III, 1150 West Medical Center Dr., Ann Arbor, MI 48109-0632, USA.)
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| Journal | American journal of physiology. Heart and circulatory physiology
(Am J Physiol Heart Circ Physiol)
Vol. 293
Issue 3
Pg. H1408-15
(Sep 2007)
ISSN: 0363-6135 United States |
| PMID | 17434982
(Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
|
| Chemical References |
- Antineoplastic Agents, Hormonal
- Troponin I
- Estradiol
- Malondialdehyde
- Medroxyprogesterone 17-Acetate
|
| Topics |
- Animals
- Antineoplastic Agents, Hormonal
(pharmacology)
- Blood Pressure
(drug effects)
- Disease Models, Animal
- Drug Interactions
- Estradiol
(therapeutic use)
- Heart
(drug effects, physiopathology)
- Heart Rate
(drug effects)
- Male
- Malondialdehyde
(metabolism)
- Medroxyprogesterone 17-Acetate
(pharmacology)
- Myocardial Infarction
(pathology)
- Myocardial Reperfusion Injury
(physiopathology, prevention & control)
- Rabbits
- Reperfusion Injury
(physiopathology, prevention & control)
- Troponin I
(blood)
|
