Influence of hypertonic bolus injection on capillary transport of water, urea and albumin in dog lung.

The influence of hypertonic bolus on dog lung capillary permeability was determine by the in vivo osmotic transient method associated with the multiple indicator dilution method. Three instantaneous injections were made (into the pulmonary artery) at 20 min intervals. The first was an isotonic bolus of 14C-Urea and 125I-Albumin tracers. The second was a hypertonic bolus of urea also with 14C-Urea and 125I-Albumin tracers. The third was identical to the first. Simultaneously, blood samples were withdrawn from the aorta and radioactive concentration of the tracers was measured. No difference between extraction of the test tracer (14C-Urea) was found between any of the three injections (=E1 = 0.108; -E2 = 0.096; -E3 = 0.096). Comparison of the permeability surface-area product values confirmed this absence of modification. It was concluded that the hypertonic bolus did not change capillary permeability to a small hydrophilic molecule and that the solvent drag induced by hyperosmotic transient was negligible.