The sustained increase in permeability produced by bradykinin is dose related

The purpose of this experiment was to determine in skin microvasculature the dose response to bradykinin (BRADY). Over a range 0, 0.2, 0.4, and 0.8 microgram/kg/min BRADY was infused into the femoral artery of anesthetized dogs while lymph was collected from the hind paw. After 4 hours of continuous BRADY, venous pressure was increased 20 to 30 mm Hg by tightening a tourniquet around the thigh to further increase lymph flow and achieve a filtration-independent lymph-plasma ratio, for albumin (R Alb), immunoglobulin G (R IgG), and immunoglobulin M (R IgM). These proteins were measured with immunoelectrophoresis and immunodiffusion. MEAN +/- SD, * p less than 0.05, ANOVA, DIFFERENT FROM LOWER DOSE. [Formula: see text] BRADY caused a dose-related increase in microvascular permeability up to 0.4 microgram/kg/min. The increase in the lymph-plasma ratio for the large plasma proteins (IgM, molecular radius 110 A) is of the same magnitude as for albumin, (molecular radius 36 A), and this suggests BRADY increased the number but not the size of "large pores" in the microvascular membrane.