THE NATURE OF TRANSCAPILLARY EXCHANGE IN THE LIVER.

The nature of transcapillary exchange in the liver was explored by applying the single-injection multiple-indicator dilution technique to the liver. Labelled red cells and a group of passively distributed substances were introduced into the portal vein in the dog. The diffusible substances were delayed during their passage through the liver and the outflow pattern produced by the delay was found, in each case, to correspond to that situation in which the diffusion of these substances across the sinusoidal wall was so rapid in relation to flow that it could be considered complete at every point along the length, a situation which may be termed flow-limited. The calculated volume of distribution for water corresponded to the actual water volume in the excised liver. The volume of distribution for the extracellular diffusible substances was shown to decrease with increase in molecular weight.