BACKGROUND: The clinical observation that coronary artery disease is more common
in men and postmenopausal women than in premenopausal women has suggested
cardioprotective effects of female sex hormones. Estrogen therapy in postmenopausal
women has been found to be associated with a decreased risk of heart disease. The
mechanisms that mediate this apparent benefit are still unclear. Suggested cardioprotective
effects of estrogen include coronary vasodilation. This study was designed to evaluate
the concentration dependent vasodilator effects of 17β-estradiol in rat aorta.
METHODS: The experimental protocol was divided into two groups. In group I tissue
was subjected to serial dilutions of norepinephrine and a standard concentration was
selected, producing approximately 75% of maximum vasoconstriction. In group II, tissue
was challenged with serial dilutions of 17β-estradiol in the presence of vasoconstriction
induced by standard concentration of norepinephrine. All the responses were recorded
as rate per 30 seconds on Kymograph machine.
RESULTS: In our study 17β-estradiol produced vasodilator effects against the
vasoconstrictor effects of norepinephrine. The difference of mean rate increased with
increasing concentration of the drug, maximum observed mean rate at the highest
concentration was 18.13±0.3 against the lowest mean rate 12.5±0.33. The difference in
mean rate in both groups was found to be highly significant (P<0.001) at all the
concentration levels except at 10-8 and 10-7 g/ml concentrations.
CONCLUSION: These results demonstrate the vasodilator effects of 17b-estradiol, in a
KEYWORDS: Estrogen, Vasodilation, Postmenopausal syndrome, Coronary artery Disease.
Coronary artery disease is one of the most common and costly diseases. Coronary vasospasm
and subsequent occlusion are frequently associated with increased cardiovascular risk
and may lead to myocardial infarction and death1. Cardiovascular disease is the leading
killer of postmenopausal wom