Aging, Serum Estradiol Levels, and Pregnancy Differentially Affect Vascular Reactivity of the Rat Uterine Artery:

Objectives:To investigate the effects of aging, ovarian ablation, and pregnancy on vascular reactivity of the rat uterine artery.Methods:Segments of uterine artery from 3-month-old pregnant and nonpregnant Wistar rats and from aged and ovariectomized animals, both 9 months of age, were exposed in vitro to vasoactive mediators. Absolute contractile force as well as endothelium-dependent and -independent vascular reactivity were determined. Isometric tension was recorded using a modified Mulvany myograph system. Results were compared with analysis of variance and Bonferroni-Dunn post hoc analysis and correlated with serum estradiol levels.Results:Aging up to 9 months decreased absolute tension of uterine arteries in vitro elicited by KCl (P < .0001), while not affecting receptor-operated responses to norepinephrine, endothelin-1, and angiotensin II. After ovarian ablation maximal contraction to norepinephrine was selectively reduced in the aged animal (P = .0053). Pregnancy increased absolute tension to KCl...