EFFECTS OF LIGATION AND EMBOLIZATION ON KF AND MULTIPLE TRACER MEASUREMENTS IN DOG LUNGS

In isolated blood-perfused dog lungs, the capillary filtration coefficient (K(f)) and the permeability-surface area product of urea (PS) were measured to determine their responses to two different methods of altering filtration area: lobe ligation (LL, n = 5) and glass bead embolization (GBE, n = 4) during constant perfusion rates (700 ± 45 ml/min). When two of three lobes were ligated, K(f) decreased (1.36 ± 0.13 to 0.58 ± 0.23 g·min-1·cmH2O-1; P < 0.05), but PS did not change (2.02 ± 0.4 to 1.71 ± 0.3 ml/s). K(f) per gram of perfused blood-free dry lung weight was unchanged by LL (0.051 ± 0.17 to 0.052 ± 0.18 g·min-1·cmH2O-1), indicating that surface area per gram measured by K(f) remained the same. However, PS per gram dry lung doubled (0.07 ± 0.016 to 0.146 ± 0.06 ml/s; P < 0.05) after LL, suggesting that recruitment occurred in the remaining lobe. When three lobes were embolized with 200-μm glass beads (0.48 ± 0.01 g beads/kg body wt), PS decreased (2.1 ± 0.22 to 0.94 ± 0.09 ml/s; P < 0.05), but K(f) was not altered (1.01 ± 0.17 to 1.04 ± 0.18 g·min-1·cmH2O-1). The constancy of K(f) after GBE implies that the vascular pressure increase during the K(f) measurement was transmitted to both blocked and flowing vessels and thereby measured the same filtration area before and after GBE. PS decreased significantly after GBE because of a loss of perfused surface area by the beads blocking flow in small arterial vessels. These results suggest that K(f) represents the filtration area of the fully recruited bed and that PS measurements are indicative of the surface area of perfused vessels.