title: Neutralization of the pharmacological effects of bothropstoxin-I from Bothrops jararacussu (jararacuçu) venom by crotoxin antiserum and heparin.
abstract: Bothropstoxin-I (BthTX-I), the principal myotoxin of Bothrops jararacussu venom, is devoid of phospholipase A(2) (PLA(2)) activity but capable of blocking neuromuscular transmission in mouse nerve-muscle preparations. In this study, the ability of crotoxin antiserum and heparin in preventing the neurotoxic and myotoxic effects of BthTX-I was investigated. Phrenic nerve-diaphragm preparations (PND) stimulated indirectly with supramaximal stimuli (0.2 ms, 0.1 Hz) were incubated with BthTX-I (20 microg/ml) alone or with BthTX-I preincubated with antiserum or heparin for 30 min at 37 degrees C prior to testing. Control preparations were incubated with Tyrode solution, antiserum or heparin alone. BthTX-I (20 microg/ml) produced 50% neuromuscular blockade in the PND preparations in 31+/-4min, with complete blockade occurring in 120 min. The antiserum and heparin significantly prevented the neuromuscular blockade caused by BthTX-I (84 +/- 4% and 100% protection, respectively). Light microscopy examination of the muscles at the end of the 120 min incubation showed that BthTX-I damaged 48 +/- 6% of the fibers. Preincubating the toxin with antivenom significantly reduced the extent of this damage (only 15 +/- 4% of fibers affected, corresponding to 69% protection, P<0.01) whereas heparin offered no protection (34 +/- 7% of fibers affected, not significantly different from that seen with toxin alone). These results show that the antivenom was more effective in neutralizing the myotoxic effects of BthTX-I than was heparin.
authors.affiliation: Department of Pharmacology, State University of Campinas (UNICAMP), 13083-970, SP, Brazil.
authors.forename: Y
authors.initials: Y
authors.lastname: Oshima-Franco
authors.forename: G B
authors.initials: GB
authors.lastname: Leite
authors.forename: G H
authors.initials: GH
authors.lastname: Silva
authors.forename: D F
authors.initials: DF
authors.lastname: Cardoso
authors.forename: S
authors.initials: S
authors.lastname: Hyslop
authors.forename: J R
authors.initials: JR
authors.lastname: Giglio
authors.forename: M A
authors.initials: MA
authors.lastname: da Cruz-Höfling
authors.forename: L
authors.initials: L
authors.lastname: Rodrigues-Simioni
mesh_terms: D000818:Animals; D000997:Antivenins / Q000276:immunology / Q000494:pharmacology* / Q000627:therapeutic use; D017837:Bothrops; D003435:Crotalid Venoms / Q000037:antagonists & inhibitors* / Q000276:immunology / Q000633:toxicity; D003439:Crotoxin / Q000037:antagonists & inhibitors* / Q000276:immunology / Q000633:toxicity; D004558:Electric Stimulation; D004591:Electrophoresis, Polyacrylamide Gel; D006493:Heparin / Q000627:therapeutic use; D007074:Immunoglobulin G / Q000032:analysis* / Q000097:blood / Q000302:isolation & purification; D066298:In Vitro Techniques; D007279:Injections, Subcutaneous; D008297:Male; D051379:Mice; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000473:pathology / Q000502:physiology; D019148:Neuromuscular Blockade; D009469:Neuromuscular Junction / Q000187:drug effects / Q000473:pathology / Q000502:physiology; D009500:Neutralization Tests; D010791:Phrenic Nerve / Q000187:drug effects* / Q000502:physiology; D011817:Rabbits; D013997:Time Factors
chemical_list: D000997:Antivenins; D003435:Crotalid Venoms; D007074:Immunoglobulin G; C078097:bothropstoxin; D006493:Heparin; D003439:Crotoxin