The role of estradiol- 17β, progesterone and prostaglandin F₂α (PGF₂α) in altering contractility of uterine vascular smooth muscle was investigated. A segment of uterine artery (3. 5 cm) supplying each uterine horn of ewes and heifers were removed at necropsy and perfused with oxygenated Krebs Henseleit Solution prior to initiating...