Characterization of phospholipase A2 activity in rat RPAR-induced pleurisy

At 10 min, 2 h and 4 h after induction of a reverse passive Arthus reaction (RPAR) in the pleural cavity of rats, pleural exudate was collected and analyzed in vitro for phospholipase A2 (PLA2) acyl hydrolytic activity. Inasmuch as exudate PLA2 was inhibited by addition of EDTA, the acyl hydrolytic...

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Bibliographic Details
Published in:Agents and Actions 1991-09, Vol.34 (1-2), p.97-99
Main Authors: Marinari, L R, Berkenkopf, J W, Weichman, B M
Format: Article
Language:English
Subjects:
Acetophenones - pharmacology
Animals
Arthus Reaction - complications
Arthus Reaction - enzymology
Calcium - physiology
Exudates and Transudates - enzymology
Phospholipases A - antagonists & inhibitors
Phospholipases A - metabolism
Phospholipases A2
Pleurisy - enzymology
Pleurisy - etiology
Proteins - metabolism
Rats
Serum Albumin, Bovine - immunology
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Summary:At 10 min, 2 h and 4 h after induction of a reverse passive Arthus reaction (RPAR) in the pleural cavity of rats, pleural exudate was collected and analyzed in vitro for phospholipase A2 (PLA2) acyl hydrolytic activity. Inasmuch as exudate PLA2 was inhibited by addition of EDTA, the acyl hydrolytic activity appeared calcium-dependent. However, addition of exogenous calcium to the exudate had only a minor effect on the activity. Maximum hydrolysis in all exudates was observed over a pH range of 6-9 with a neutral optimum. The 4 h exudate PLA2 activity was almost fully inhibited by para-bromophenacyl bromide (pBPB), whereas the acyl hydrolytic activity in the 10 min and 2 h exudates was reduced by 44% and 46%, respectively, by 200 microM pBPB. Although the PLA2 in the 4 h exudate displayed an increased sensitivity to high exogenous calcium concentrations and to pBPB inactivation, the basic properties of the exudate PLA2 at the three time points appeared similar.
ISSN:0065-4299
1420-908X
DOI:10.1007/BF01993248