Effect of Chronic Administration of Estradiol on Responsiveness of Isolated Systemic and Pulmonary Blood Vessels from Ovariectomized Wistar Rats with Hypoxic Pulmonary Hypertension

The long-term (4 weeks) administration of estradiol (15 mu g/kg/day) to ovariectomized female Wistar rats induced hypoxic pulmonary hypertension and significantly (p < 0.05) diminished relaxation of perfused serotonin-preconstricted isolated vascular segments of the pulmonary artery in response to estradiol (10(-6) M). At the same time, the isolated segments of systemic popliteal artery demonstrated a diminished response to serotonin and increased relaxation induced by acetylcholine (10(-5) M) or estradiol (10(-5) M) in comparison with preconstricted control vessels. Moderation of responsiveness to estradiol in pulmonary circulation can be one of the factors underlying the pro-hypertensive action of estradiol in female rats with hypoxic pulmonary hypertension.