Posted in Volume 15 - Number 3
NAZIR AHMED SHAH, KAUSAR AAMIR, SALAHUDDIN QURESHI, BARKAT ALI SHAIKH, SHAMAMA BASHIR
ABSTRACT | Full Text PDF
BACKGROUND: The clinical observation that coronary artery disease is more commonin 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 concentration-dependent manner.
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