title: Pharmacological study on phospholipases A2 isolated from Naja mossambica mossambica venom.
abstract: The pharmacological properties of three phospholipases A2 (CM-I, CM-II and CM-III) purified from Naja mossambica mossambica venom were studied. The order of their catalytic and indirect hemolytic potencies was CM-I = CM-II greater than CM-III. Among them, only CM-III had a direct hemolytic action on the guinea-pig RBC, which was greatly inhibited by heparin. In the chick biventer cervicis nerve- muscle preparation, both CM-II and CM-III caused neuromuscular blockade with a gradual contracture and a decreased sensitivity to ACh and KCl, whereas no complete neuromuscular block was observed with CM-I up to 30 micrograms/ml. In the mouse phrenic nerve-diaphragm preparation, these three PLA2s abolished twitches evoked by indirect stimulation earlier than those by direct stimulation. Contracture was also produced by CM-II and CM-III. However only the latter was inhibited by pretreatment with heparin. These PLA2s caused myonecrosis in the hind-leg muscle of the mouse when injected intramuscularly. From these results, it is concluded that all of these PLA2s are both neurotoxic and myotoxic.
mesh_terms: D000818:Animals; D002645:Chickens; D004546:Elapid Venoms; D006461:Hemolysis; D007700:Kinetics; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D009119:Muscle Contraction / Q000187:drug effects; D009132:Muscles / Q000187:drug effects / Q000648:ultrastructure; D009469:Neuromuscular Junction / Q000187:drug effects; D010740:Phospholipases / Q000494:pharmacology*; D010741:Phospholipases A / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D004546:Elapid Venoms; D010740:Phospholipases; D010741:Phospholipases A