Fluid filtration coefficient of isolated goat lungs was unchanged by endotoxin

Abstract

The Starling fluid filtration coefficient (Kf) of blood-perfused excised goat lungs was examined before and after infusion of Escherichia coli endotoxin. Kf was calculated from rate of weight gain as described by Drake et al. [Am. J. Physiol. 234 (Heart Circ. Physiol. 3): H266-H274, 1978]. These calculations were made twice during base line and then at hourly intervals for 5 h after infusion of 5 mg (approximately 250 micrograms/kg) of E. coli endotoxin or after injection of oleic acid (47 microliter/kg). All lungs were perfused at constant arterial and venous pressure under zone 3 conditions. Base-line Kf averaged 27 +/- 10 and 20 +/- 4 (SD) microliter.min-1.cmH2O-1.g dry wt-1 for endotoxin and oleic acid groups, respectively. It was unchanged in the endotoxin group throughout the experiment but approximately doubled in the oleic acid lungs. Pulmonary arterial and venous pressures were not changed significantly during the course of these experiments in either group. Lung wet-to-dry weight ratios of these lungs were 5.6 +/- 0.6 and 6.1 +/- 0.5 ml/g for the endotoxin and oleic acid groups, respectively. This compares with 4.6 +/- 0.5 ml/g for normal, freshly excised but not perfused goat lungs. The small change in lung water and unchanged pulmonary pressures after both endotoxin and oleic acid suggest that lung injury was minimal. We conclude that 1) endotoxin does not cause a direct injury to the endothelium of isolated lungs during the first 5 h of perfusion, and 2) neutrophils are not sufficient to cause increased Kf after endotoxin infusion in this preparation.