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Contraction of guinea pig lung parenchyma by pancreatic type phospholipase A 2 via its specific binding site
Author(s) -
Toshiyuki Kanemasa,
Akinori Arimura,
Junji Kishino,
Masahiro Ohtani,
Hitoshi Arita
Publication year - 1992
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(92)80523-j
Subject(s) - phospholipase a2 , guinea pig , thromboxane a2 , thromboxane , contraction (grammar) , medicine , leukotriene , receptor , antagonist , endocrinology , biology , parenchyma , cyclooxygenase , chemistry , biochemistry , enzyme , platelet , botany , asthma
Porcine pancreatic group I phospholipase A 2 (PLA 2 ‐I) induced contraction of guinea pig lung parenchyma in a concentration‐dependent manner. Its EC 50 value was similar to the K d value calculated from the specific binding of 125 I‐labeled porcine PLA 2 ‐I in the membrane fraction of guinea pig lung. Type‐specific action of PLA 2 's and homologous desensitization strongly implicated the involvement of PLA 2 ‐I‐specific sites in the activation process. Throm☐ane A 2 was found to be the main product from lung tissue by PLA 2 ‐I action and the contractile response by PLA 2 ‐I was specifically suppressed by throm☐ane A 2 receptor antagonists and cyclooxygenase inhibitor, but not by leukotriene receptor antagonist and H1 blocker. These findings indicate that PLA 2 ‐I‐induced contractile response may depend on the secondarily produced throm☐ane A 2 , thus providing a new aspect of PLA 2 ‐I from the pathophysiological standpoint.