Lysosomal activity of pulmonary alveolar macrophages in acute experimentalpancreatitis in rats with reference to positive PAF-antagonist (BN 52021) effect

The activation of pulmonary alveolar macrophages (PAM's), might play an imp ortant role in severe complications of acute pancreatitis. The aim of our s tudy was to assess the labilization of macrophage lysosomal membranes and r elease of lysosomal cathepsin B (CB) and N-acetyl-beta-D-hexosaminidase (NA H) into bronchoalveolar lavage fluid (BALF) during taurocholate acute pancr eatitis (AP) in rats treated with PAF-antagonist - BN 52021. Total activity of CB increased by 374 % after 6 h and by 237 % after 12 h of AP in lysoso mal enriched fraction of PAM's. Fractional free activity of CB increased to 40 % after 6 h and to 38 % after 12 h of AP. Free activity of CB was incre ased 5 fold in the supernatant of macrophage homogenate, and 10 fold in the supernatant of BALF after 6h of AP. The values of NAH activity roughly par alleled that of CB. Treatment with BN 52021 (5 mg . kg(-1) every 6 h i.v.) partially normalized the measured parameters. Our results indicate that the PAF-antagonist BN 52021 reduced the increase of total and free activity of lysosomal hydrolases of PAM's and partly prev ented the labilization of their lysosomal membranes. Therefore, an importan t mechanism of BN 52021 beneficial effect in pulmonary complications of acu te pancreatitis could be dependent on the stabilization of PAM's lysosomes.