Contraction of guinea pig lung parenchyma by pancreatic type phospholipase A2 via its specific binding site

FEBS Lett. 1992 Jun 1;303(2-3):217-20. doi: 10.1016/0014-5793(92)80523-j.


Porcine pancreatic group I phospholipase A2 (PLA2-I) induced contraction of guinea pig parenchyma in a concentration-dependent manner. Its EC50 value was similar to the Kd value calculated from the specific binding of 125I-labeled porcine PLA2-I in the membrane fraction of guinea pig lung. Type-specific action of PLA2's and homologous desensitization strongly implicated the involvement of PLA2-I-specific sites in the activation process. Thromboxane A2 was found to be the main product from lung tissue by PLA2-I action and the contractile response by PLA2-I was specifically suppressed by thromboxane A2 receptor antagonists and cyclooxygenase inhibitor, but not by leukotriene receptor antagonist and H1 blocker. These findings indicate that PLA2-I-induced contractile response may depend on the secondarily produced thromboxane A2, thus providing a new aspect of PLA2-I from the pathophysiological standpoint.

MeSH terms

  • Animals
  • Binding Sites
  • Contracture / metabolism*
  • Guinea Pigs
  • In Vitro Techniques
  • Lung / metabolism*
  • Lung / physiology
  • Male
  • Pancreas / enzymology*
  • Phospholipases A / metabolism*
  • Phospholipases A2
  • Thromboxane A2 / metabolism


  • Thromboxane A2
  • Phospholipases A
  • Phospholipases A2