title: Effect of prolonged alveolar hypoxia on pulmonary arterial pressure and segmental vascular resistance.
abstract: The time course of hypoxic pulmonary vasoconstriction and its segmental distribution were studied during prolonged (150 min) alveolar hypoxia in in vivo dog lungs at constant-flow perfusion. With the pulmonary and the systemic circulations separated by two extracorporeal circuits, adequate systemic oxygenation was achieved throughout the experiments. The pulmonary circulation exhibited a time-related biphasic hypoxic vasoconstrictor response: an initial rapid contraction [79 +/- 11% (SE) above control level] was followed by a partial relaxation when a second slow and sustained vasoconstriction (92 +/- 13% above control level) superseded. We partitioned the pulmonary circulation into two segments by arterial occlusion: an upstream arterial segment and a downstream segment consisting of a middle and a venous segment. Measurements were performed at baseline and during the late sustained vasoconstrictor response. Prolonged alveolar hypoxia increased pulmonary capillary pressure by 90 +/- 18%, the site of pulmonary vasomotion being the arterial upstream and downstream middle and venous segments.
authors.affiliation: Department of Cardiology, Gentofte Hospital, University of Copenhagen, Hellerup, Denmark.
authors.forename: K L
authors.initials: KL
authors.lastname: Welling
authors.forename: R
authors.initials: R
authors.lastname: Sanchez
authors.forename: J B
authors.initials: JB
authors.lastname: Ravn
authors.forename: B
authors.initials: B
authors.lastname: Larsen
authors.forename: O
authors.initials: O
authors.lastname: Amtorp
mesh_terms: D000818:Animals; D001794:Blood Pressure; D004285:Dogs; D005260:Female; D000860:Hypoxia / Q000503:physiopathology*; D008297:Male; D011650:Pulmonary Alveoli; D011651:Pulmonary Artery / Q000503:physiopathology*; D013997:Time Factors; D014655:Vascular Resistance