Blood Volume and Extravascular Water Content in the Rat Lung during Acute Alveolar Hypoxia

Abstract

Values for pulmonary blood volume and extravascular lung water (estimated as wet weight of lung tissue) were arrived at in intact, anesthetized rats by labeling of blood constituents with isotopes and rapidly freezing the whole animals in liqud N2. On ventilating the animals with 10% O2 in N2/N2O, a reduction in lung blood content was demonstrated. The degree of reduction depended on the type of anesthesia and ventilation used. In some animals the volume reduction was so marked that both arterial, venous and capillary blood compartments were most probably involved. The water content of the lung tissue was also rapidly and markedly reduced during hypoxia. Increased plasma osmolarity in mixed venous blood could partly be responsible for this tissue water reduction.