Guinea pig plasma kallikrein as a vascular permeability enhancement factor. Its dependence on kinin generation and regulation mechanisms in vivo.

Plasma kallikrein (mol wt 80,000) was purified from guinea pig plasma, and it caused vascular permeability enhancement when injected into guinea pig skin. The activity had a linear relationship to the logarithm of kallikrein concentrations from 5 X 10(-9) M to 5 X 10(-6) M and was blocked by immunopurified anti-prekallikrein F(ab')2 rabbit antibody and soybean trypsin inhibitor. Carboxypeptidase B(1.7 units), a kinin-destructive enzyme, decreased the permeability activity to 1/20, while SQ 20,881 (10(-6) M), an inhibitor to a kinin-destructive enzyme, augmented the activity 5.4-fold. These results suggested that the permeability activity of kallikrein was performed finally through kinin generation in the skin. The permeability activity was short-lasting, and was completely blocked by a kallikrein inhibitor purified from guinea pig plasma, suggesting the presence of a down-regulation system for the permeability activity in vivo. Prostaglandin E2 (25 ng), a hyperemia inducer in microcirculation, augmented the permeability activity 12-fold, suggesting the presence of an up-regulation system in vivo. Accordingly, it was assumed that kallikrein-kinin system might play a role as a vascular permeability enhancement system in guinea pig skin.