Convulxin (Cx), a component of the venom of the snake Crotalus durissus cascavella, induced the concentration-dependent aggregation of @entity840 platelets when used at and above 50 +/- 5 ng/ml, accompanied by the release of @entity855 and by the formation of @entity37814 (Tx). Platelet activation by Cx was not due to potential contaminants found in the crude snake venom, such as phospholipase A2 and clotting enzymes. @entity117 (50-100 microM) failed to interfere with the platelet effects of Cx, demonstrating independence from cyclo-oxygenase. In contrast, @entity3352 (50 microM) displayed a distinct inhibitory activity on the effects of Cx, as compared to @entity117 , and thus exerts cyclo-oxygenase-independent effects on platelet activation. The @entity857 scavenger @entity1734 / @entity908 phosphokinase (CP/CPK) inhibited aggregation by Cx used at concentrations below 6-8 times the threshold, but failed to interfere with higher amounts. Platelet aggregation by Cx was inhibited and reversed once established by @entity1098 (5mM) and by @entity4770 (0.1-1 microM). Cx-induced activation of platelets is thus @entity141 -dependent and liable to control by the adenylate cyclase- @entity1919 system. @entity32782 induced @entity551 , bronchoconstriction and @entity882 when injected i.v. to the anesthetised @entity840 at 0.3-3 microgram/kg. @entity117 and @entity3352 (20 and 5 mg/kg respectively) @entity8765 and @entity3858 (02. mg/kg) failed to interfere with these effects, but the combination of either @entity117 or @entity3352 with @entity3858 and @entity8765 , suppressed the bronchial effects of Cx, leaving the @entity551 and @entity14628 effects unchanged. This synergism remains unexplained. Bronchoconstriction was platelet-dependent, being suppressed by platelet depletion with antiplatelet serum or by i.v. @entity4770 (1-10 microgram/kg).

Activation of XXXX platelets induced by convulxin, a substance extracted from the venom of Crotalus durissus cascavella.

@entity32782 :: ('MESH:C028890', 'Chemical') :: ['Convulxin'] @entity1734 :: ('CHEBI:17287', 'Chemical') :: ['creatine phosphate'] @entity3858 :: ('MESH:D008784', 'Chemical') :: ['methysergide'] @entity882 :: ('MESH:D013921', 'Disease') :: ['thrombocytopenia'] @entity857 :: ('MESH:D000244', 'Chemical') :: ['ADP'] @entity908 :: ('MESH:D003401', 'Chemical') :: ['creatine'] @entity117 :: ('MESH:D001241', 'Chemical') :: ['Aspirin', 'aspirin'] @entity840 :: ('10141', 'Species') :: ['guinea-pig', 'guinea pig'] @entity4770 :: ('MESH:D011464', 'Chemical') :: ['prostacyclin'] @entity8765 :: ('MESH:D011738', 'Chemical') :: ['mepyramine'] @entity1919 :: ('MESH:D000242', 'Chemical') :: ['cyclic AMP'] @entity141 :: ('CHEBI:29108', 'Chemical') :: ['Ca2+'] @entity3352 :: ('MESH:D007213', 'Chemical') :: ['indomethacin'] @entity37814 :: ('MESH:D013931', 'Chemical') :: ['thromboxanes'] @entity551 :: ('MESH:D007022', 'Disease') :: ['hypotensive', 'hypotension'] @entity14628 :: ('MESH:D011696', 'Disease') :: ['thrombopenic'] @entity1098 :: ('MESH:D004492', 'Chemical') :: ['EDTA'] @entity855 :: ('MESH:D000255', 'Chemical') :: ['ATP']
@entity840 :: (10141,Species) :: ['guinea-pig']
