Objective: Our purpose was to study the direct vascular effects of estradiol-17 beta and progesterone on isolated omental artery from premenopausal nonpregnant women and from normotensive and preeclamptic pregnant women.
Study design: Omental artery rings from normotensive premenopausal nonpregnant women and from normal and preeclamptic pregnant women were mounted in Krebs-bicarbonate solution in organ baths for isometric tension recording. The endothelium was removed from some of the rings, and all were contracted with potassium chloride (60 mmol/L) and then exposed to cumulative concentrations of estradiol-17 beta and progesterone. Concentration response curves were constructed and relaxation was expressed as percent change from the reference 60 mmol/L potassium chloride contraction. Data analysis was by repeated-measures analysis of variance, Newman-Keuls test, and the unpaired Student t test as appropriate. A two-tailed p < 0.05 was considered statistically significant.
Results: Both hormones studied caused vasorelaxation in omental arteries from all three groups of patients. Of the two, estradiol-17 beta was more effective, regardless of the presence or absence of endothelium. Removal of the endothelium shifted the estradiol-17 beta concentration-response curve to the right in the normal pregnant artery but not in nonpregnant or preeclamptic vessels. Removal of the endothelium shifted the progesterone concentration-response curve to the left in arteries from preeclamptic patients.
Conclusions: Estradiol-17 beta and progesterone have direct in vitro vasodilator activity that appears to be linked, in part, to the endothelium in human omental artery from normal and hypertensive women in different hormonal states.