Effects of transpulmonary and vascular pressures on pulmonary blood volume in isolated lung.

Efects of transpulmonary and vascular pressures on pulmonary blood volume in isolated lung. J. Appl. Physiol. 28(5) : 553-560. 1970.-By re-peatedly weighing the isolated perfused greyhound lung, we studied changes in pulmonary blood volume resulting from varia-tions in vascular and transpulmonary pressures. Lung weight increased linearly when arterial pressure was raised over the O-25 cm Hz0 range, but the rate of change was greatest at moderate inflation corresponding to 5-l 0 cm Hz0 transpulmonary pressure (Ptp). The response to changing venous pressure was similar. At constant vascular pressures, changes in Ptp produced different weight changes according to the relation between vascular and alveolar pressure. When vascular pressures exceeded alveolar pressure, the greatest weight change occurred at low Ptp, but when vascular pressures were less than alveolar pressure, greater weight gain occurred at high Ptp. We attempted to separate these changes