The Protective Effect Of Estrogen For Myocardial Ischemia And Injury Of Homocystein In Rats

Object: The dramatic impact of estrogen on cardiovascular health is apparent from population-based studies, which indicate that premenopausal women have little coronary artery disease compared with men, the ratio is 3:1-10:1, that the incidence of the disease rises markedly after menopausal, and the hormone replacement therapy (HRE) under certain conditions reduces the risk to premenopausal levels. In addition, women who undergo surgical menopausal without estrogen replacement have two times the risk of coronary artery disease than other premenopausal women. Suggesting that estrogen play a significant role in the development of cardiovascular disease. However, only approximately one third of the clinical advantages of estrogen can be attributed to effects on lipid balance. Recent evidence indicates that estrogen acts directly on the blood vessel wall to provide a major atheroprotective effect. The result of heart and estrogen/progestin replacement study (HERs) indicates endpoint events increase at the end of one year. So, we interested in estrogen has advantage effect or not? This study made model of ischimia/reperfusion on isolated heart in rat and concentrated on the acute vascular effects of estrogen.Methods: The model of ischimia/reperfusion on isolated heart was produced by ligation the left anterior descending coronary artery in Wistar rats, and reperfusion after 10-15 minutes. Rats were randomized to control group (Krebs-Henseleit solution , n=12),estrogen group(in perfused hearts treated with 10^-6 mol/L 17beta-estradiol water soluble, n=8), homocysteine group(in perfused hearts treated with 10^-4 mol/L homocysteine, n=10) and estrogen+ homocysteine group(in perfused hearts treated with 10^-6 mol/L 17 beta- estradiol water soluble and 10^-4 mol/L homocysteine, n=10). We observed and recorded the rhythm, rate and coronary flow of the isolated heart. The gene expression of endothelial isoform of NO synthase , angiotensionll type 2 receptor(AT2) were measured by reverse transcription-polymerase chain reaction (RT-PCR) method. The activities of cardiac muscle angiotensionll and endothelin were examined by the method of radioimmunoassay test.