Journal of Applied Physiology, Vol 46, Issue 1 100-110, Copyright © 1979 by American Physiological Society
DLO2 in excised lungs perfused with blood containing sodium dithionite (Na2S2O4)
B. Burns and R. H. Shepard
If the excised lung is perfused with blood containing the chemical sodium
dithionite (DDT), the PO2 of pulmonary capillary blood is everywhere zero
and the membrane diffusing capacity for O2 (DmO2) can be measured by a
standard rebreathing technique. The reaction rate of DDT with O2 is not
rate limiting in the DmO2. In 15--25 kg dogs anesthetized with
pentobarbital sodium (30 mg/kg, iv), left lower lobe was excised, suspended
horizontally and perfused with autologous blood at 25--27 degrees C. DDT
was added to the blood and the rebreathing alveolar disappearance curves
for O2 were measured. The DmO2 ranged from 6 to 43 (ml/min.Torr, STPD) at
lung volumes of 240--780 ml (FRC at 6 cmH2O end-expiratory pressure). Lung
weight, pulmonary artery pressure, and the DmO2 were stable in the presence
of DDT. Histopathology indicates that dithionite in the concentrations used
does not harm the lung. Effects of inequalities in the distributions of
ventilation, volume, and diffusing capacity were examined in a
two-compartment model and compared with the experimental findings.
