Rat Paw Oedema and Mast Cell Degranulation Caused by Two Phospholipase A2 Enzymes Isolated From Trimeresurus mucrosquamatus Venom

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Abstract
Two phospholipase A2 (PLA2) enzymes, TMVPLA2 I and TMVPLA2 II, isolated from Trimeresurus mucrosquamatus venom (TMV) induce rat hind-paw oedema in a dose-dependent manner. This response is suppressed by pretreatment with diphenhydramine, methysergide or compound 48/80, which reduces tissue histamine content. In isolated mast cells, TMVPLA2 I and TMVPLA2 II cause concentration-, time-and calcium-dependent release of histamine and β-glucuronidase. This effect is inhibited by disodium cromoglycate, mepacrine, nordihydroguaiaretic acid, piriprost and BW 755C, but not by aspirin or indomethacin. These observations indicate that the mast cell plays a predominant role in TMVPLA2 I-and TMVPLA2 II-induced paw oedema, and that venom PLA2 enzyme needs an intact lipoxygenase pathway to induce mast cell degranulation.