Extravascular distribution of albumin and IgG during high-permeability edema in skin.

The effects of local intra-arterial infusions of bradykinin on the interstitial distribution of albumin and gamma-immunoglobulin G (IgG) was studied in hind paw skin of anesthetized rabbits. After 4 h of a continuous bradykinin infusion, lymph flow in a prenodal popliteal lymphatic was five times base line. The lymph-to-plasma concentration ratio for total protein was increased by 34%. Samples of heel skin were taken at the end of the experiment. The extracellular and plasma spaces in the tissue samples were measured using 51Cr-labeled ethylenediaminetetraacetic acid and 125I-labeled human serum albumin, respectively. The protein spaces were calculated from measurements of endogenous albumin and IgG concentrations using rocket electroimmunoassay. After bradykinin, the interstitial volume was 28% greater than control, whereas the extravascular masses of albumin and IgG were twice as great as the control values. Based on lymph concentration, both proteins distributed in 50% of the interstitial volume during control. Following bradykinin, both proteins distributed in a greater fraction of the interstitium. However, the excluded volume, equal to 0.9 ml/g dry wt, was not altered after bradykinin. This may indicate an increase in free-fluid channels with no hydration of the interstitial gel matrix.