[Role of changes in the hemodynamics of the pulmonary circulation in pulmonary gas exchange].

High pressure in the lung artery was maintained with the aid of i. v. serotonin administration (0.5 mg/ml) in dogs during 10 min. The simultaneous increase of the intravascular pressure in minor circulation and of the lung volume circulation was followed by an increasing blood volume in lungs, diffusion capacity of lungs, oxygen tension in the arterial blood, and satiation of the latter with oxygen. The combined action of the above two hemodynamic factors aids to opening of latent vascular areas, to a more regular distribution of perfusion over the lung areas according to the ventilation level. This mechanism seems to be one of the first compensatory responses to disturbances in the lung gas exchange.