Plasma-lymph albumin kinetics, total lymph flow, and tissue hematocrit in normally hydrated dog lungs.

Lung lymph flow was normalized for lung weight and total lung lymph flows were calculated in five mongrel dogs using a kinetic analysis of albumin distribution between the pulmonary capillaries, interstitial fluid, and pulmonary lymph. Using prenodal tracheobronchial lymph an intravenous bolus of 125I-labeled albumin equilibrated between plasma and lymph with mean T1/2 of 2 hr 22 min. The mean volume of interstitial fluid drained by the cannulated lymphatics was 9.9 ml which corresponded to the extravascular albumin distribution volume of 31% of the total lung weight. Lung tissue hematocrit was determined using 51Cr-labeled red cells and 125I-albumin and averaged 92% of the simultaneous mixed venous hematocrit. The extravascular albumin and 99mTc-DTPA (diethylenetriamine pentacetic acid) spaces in lung were corrected for differences between tissue and mixed venous hematocrit and were 18.5 and 33.0 ml/100 g, respectively. This indicated that albumin distributed in 57% of the interstitial volume at 4 hr after injection. Lung lymph flow normalized to postmortem lung mass during baseline conditions was 0.060 ml/min/100 g after correction for tissue hematocrit differences. Normalized lymph flows are used for quantitative comparisons of lung lymph protein flux data between different types of experiments.