On the kinin factors in rat pleural exudate.

Abstract

Methods have been described to obtain a kininase free substrate from a turpentine-induced rat pleural exudate (24 h post-turpentine) and for the determination of kininase activity and total kininogen in such exudates. With the methods used, a mean of 7.4 min was necessary for 0.25 ml of exudate to inactivate 50% of a given amount (1 µg) of added brady-kinin. Total kininogen in exudate with leukocytes and without leukocytes were 1.97 µg/ml and 1.80 µg/ml, respectively, calculated as bradykinin. It was concluded that most of the kininogen in pleural exudate is present in the cell-free supernatant. Evidence was put forward that the rat uterus-stimulating agents that develop in the exudate upon activation with acetone are kinins not significantly contaminated with other smooth muscle-stimulating agents such as, for instance, histamine and serotonin. The conclusion was drawn that pleural exudate obtained 24 h post-turpentine in the rat is a transudate of rat plasma and that the kinin system could play a role, locally, in bringing about formation of the exudate.