Isolation of pulmonary interstitial fluid in rabbits by a modified wick technique

Interstitial fluid protein concentration (C-protein) values in perivascular and peribronchial lung tissues were never simultaneously measured in mamma ls; in this study, perivascular and peribronchial interstitial fluids were collected from rabbits under control conditions and rabbits with hydraulic edema or lesional edema. Postmortem dry wicks were implanted in the perivas cular and peribronchial tissues; after 20 min, the wicks were withdrawn and the interstitial fluid was collected to measure C-protein and colloid osmo tic pressure. Plasma, perivascular, and peribronchial C-protein values aver aged 6.4 +/- 0.7 (SD), 3.7 +/- 0.5, and 2.4 +/- 0.7 g/dl, respectively, in control rabbits; 4.8 +/- 0.7, 2.5 +/- 0.6, and 2.4 +/- 0.4 g/dl, respective ly, in rabbits with hydraulic edema; and 5.1 +/- 0.3, 4.3 +/- 0.4 and 3.3 /- 0.6 g/dl, respectively, in rabbits with lesional edema. Contamination of plasma proteins from microvascular lesions during wick insertion was 14% o f plasma C-protein. In control animals, pulmonary interstitial C-protein wa s lower than previous estimates from pre- and postnodal pulmonary lymph; fu rthermore, although the interstitium constitutes a continuum within the lun g parenchyma, regional differences in tissue content seem to exist in the r abbit lung.