| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 2066273 | Toxicon | 2006 | 7 Pages |
The whole venom of Lachesis muta muta is preponderantly neurotoxic but moderately myotoxic on the chick biventer cervicis preparation (BCp). We have now examined these toxic activities of a basic phospholipase A2, LmTX-I, isolated from the whole venom. LmTX-I caused a significant concentration–dependent neuromuscular blockade in the BCp. The time to produce 50% neuromuscular blockade was 14.7±0.75 min (30 μg/ml), 23.6±0.9 min (10 μg/ml), 34±1.7 min (2.5 μg/ml) and 39.2±3.6 min (1 μg/ml), (n=5/concentration; p<0.05). Complete blockade with all tested concentrations was not accompanied by inhibition of the response to ACh. At the highest concentration, LmTX-I (30 μg/ml) significantly reduced contractures elicited by exogenous KCl (20 mM), increased the release of creatine kinase (1542.5±183.9 IU/L vs 442.7±39.8 IU/L for controls after 120 min, p<0.05), and induced the appearance of degenerating muscle fibers (∼15%). Quantification of myonecrosis indicated 14.8±0.8 and 2.0±0.4%, with 30 and 10 μg/ml venom concentration, respectively, against 1.07±0.4% for control preparations. The findings indicate that the basic PLA2 present on venom from L. m. muta (LmTX-I) possesses a dominant neurotoxic action on isolated chick nerve-muscle preparations, whereas myotoxicity was mainly observed at the highest concentration used (30 μg/ml). These effects of LmTX-I closely reproduce the effects of the whole venom of L. m. muta in chick neuromuscular preparations.
