Abstract
Summary
The purpose of this study was to determine whether acute hypoxia in vitro or chronic hypobaria alter the response of pulmonary artery smooth muscle to vasoactive substances proposed as mediators of hypoxic pulmonary vasoconstriction. Dose response curves to PGF2α, A-II, EPI, NE, and 5-HT were obtained on helical strips of pulmonary artery and thoracic aorta from normal and chronically hypobaric (one-half atmosphere for 2 weeks) rats, under the conditions of high and low oxygen tension in the tissue bath. Chronic hypobaria increased the reactivity of pulmonary artery to PGF2α and decreased it to A-II when compared to normal rats. Acute hypoxia did not change the reactivity of pulmonary artery to any of the agents tested. Similar changes were not observed in aorta.
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