Unchanged pulmonary capillary filtration coefficients after Escherichia coli endotoxin infusion

The pulmonary capillary filtration coefficient (K_f,c) was measured in intact, anesthetized dogs before and after the intravenous administration of alloxan and E. coli endotoxin. The method used to measure K_f,c was that of determining the capillary filtration rate by analyzing the weight transient following a change in capillary pressure (ΔP_c) and dividing the initial filtration rate by ΔP_c. In four dogs given 75 mg/kg of alloxan, the K_f,c increased 10-fold. This indicated that the capillary membranes were damaged by the alloxan and that, by using this method of measuring K_f,c, changes in K_f,c were easily detected. The K_f,c, measured after a 3-hr continuous infusion of a total of 4 mg/kg of E. coli endotoxin [0.35 ± 0.21 (SD) ml/min/mm Hg/100g], was not different from the value found in the same animals before the endotoxin (0.33 ± 0.29). Since the K_f,c is a sensitive indicator of capillary membrane pore size, these results strongly suggest that E. coli infusion did not damage the pulmonary capillary membrane.