抄録
Pleurisy was induced by intrapleural injection of compound 48/80 (5μg/0.5ml) to Sprague-Dawley rats (male 8-9 weeks old) . Plasma exudation was observed only in the first 20 min period. The residual levels of plasma prekallikrein (pre-K) and high molecular weight (HMW) kininogen (KGN) in the exudate of this period were found to be markedly reduced and that of low molecular weight (LMW) -KGN was reduced by 58%. The sinmilar results were obtained after in vitro incubation of plasma with pleural and peritoneal mast cells stimulated by compound 48/80 or purified mast cells degranulated by this histamine releaser. Amidase activity, cleaving Pro-Phe-Arg-MCA, appeared in peritoneal and pleural mast cells one minute after degranulation by compound 48/80. The activity was not attributable to plasma- or tissue- kallikrein, but to chymotrypsin-like and trypsin-like proteases, since the activity was not completely suppressed by soy bean trypsin inhibitor or aprotinin, but was inhibited to 6% by combination of chymostatin and leupeptin. As the residual levels of pre-K and HMW-KGN were reduced in the exudate, even if measured in the presence of chymostatin and leupeptin, it is supposed that these proteases may have inactivated not only factor XII but also pre-K, HMW-KGN and LMW-KGN.
