Bradykinin levels in inflammatory exudates

An enzyme immunoassay was used to measure the levels of bradykinin (BK)-like immunoreactivity in inflammatory exudates provoked by calcium pyrophosphate (CaPP) or carrageenin. BK-like immunoreactivity increased from 4 to 18 ng/ml in exudates provoked by CaPP and collected from 30 min to 3 h after induction of pleurisy. BK levels decreased progressively (from 16 to 3 ng/ml) in the samples collected at 4 and 6 h. BK levels did not increase in exudates provoked by carrageenin. Control samples of exudates provoked by CaPP but not treated with peptidase inhibitors [orthophenanthroline (OPH) or a mixture of EDTA-captopril-thioglycolic acid (ECT)] as well as samples containing one or the other peptidase inhibitors dissolved in saline, were also negative. The present results indicate that an increased production of kinins is detectable only in exudates induced by CaPP and not in those provoked by carrageenin. Our data also suggest that the kinins are rapidly metabolized, both in vitro (in the exudate sample) and in vivo (in the rat pleural cavity).