Effect of inflation of the lung on different parts of pulmonary vascular bed

In excised lungs of dogs, the static pressure-volume characteristics of the vascular bed were determined with the vessels filled with dextran and again after replacement of the dextran with kerosene. Whereas the dextran was distributed throughout the entire vascular bed, the kerosene was distributed only in relatively large vessels due to interfacial tension. Volume-pressure curves obtained with kerosene were markedly different from those obtained with dextran. Utilizing both types of volume-pressure curves, it was possible to separate the vascular bed of the lung into two compartments that responded oppositely to inflation of the lung when vascular pressure was held constant: one compartment, consisting of relatively large vessels, always increased in volume; the other compartment, consisting of smaller vessels, always decreased in volume. Submitted on June 9, 1960