Mn(2+) ions reduce the enzymatic and pharmacological activities of bothropstoxin-I, a myotoxic Lys49 phospholipase A(2) homologue from Bothrops jararacussu snake venom.

Abstract

Bothropstoxin-I (BthTX-I), a myotoxic Lys49 phospholipase A(2) (PLA(2)) homologue isolated from Bothrops jararacussu snake venom, causes a range of biological effects, including myonecrosis, mouse paw edema, irreversible neuromuscular blockade and lysis of cell cultures. Among eight divalent cations assayed, Mn(2+) was the most effective in reducing mouse paw edema induced by BthTX-I (25 microg). Preincubating BthTX-I with Mn(2+) (1.0mM) reduced mouse paw edema by 70% and myotoxicity by 60% in mice injected i.m. with 50 microg toxin. Mn(2+) (50 microl of a 1mM solution) administered within 1min at the site of toxin injection was still but less effective in antagonising BthTX-I-induced myotoxicity. Mn(2+) (1.0mM) completely prevented BthTX-I (1.4 microM)-induced neuromuscular blockade in the mouse phrenic-nerve diaphragm preparation. Mn(2+) (0.25mM) protected about 85% of NB41A3 cells from lysis when coincubated with BthTX-I (1.0 microM) for 25h. Preincubation with 0.25mM Mn(2+) increased the sensitivity of the cells to subsequent lysis by BthTX-I in the absence of Mn(2+). BthTX-I (1 microM) caused extensive fatty acid release (from 0.8% of the total radiolabeled lipid in control cells to 56% with toxin) when incubated with the NB41A3 cell line for 25h. PLA(2) activity observed in cell cultures after addition of BthTX-I was considerably reduced by 0.25mM Mn(2+). Mn(2+) ions constitute a promising agent to assess the action mechanism and the effects of enzymatic inhibition on the pharmacological activity of Lys49 PLA(2) homologues.

• Authors: Andreimar M Soares, Yoko Oshima-Franco, Carlos A Vieira, Gildo B Leite, Jeffrey E Fletcher, M-S Jiang, Adelia C O Cintra, José R Giglio, Léa Rodrigues-Simioni
• Journal: The international journal of biochemistry & cell biology (Int J Biochem Cell Biol) Vol. 34 Issue 6 Pg. 668-77 (Jun 2002) ISSN: 1357-2725 [Print] Netherlands
• PMID: 11943597 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Cations, Divalent
• Crotalid Venoms
• Lipids
• bothropstoxin
• Manganese
• Phospholipases A

Topics

• Animals
• Bothrops
• Cations, Divalent (metabolism)
• Cell Survival (drug effects)
• Crotalid Venoms (enzymology, pharmacology)
• Diaphragm (drug effects, physiology)
• Dose-Response Relationship, Drug
• Edema (chemically induced)
• In Vitro Techniques
• Injections, Intramuscular
• Kinetics
• Lipids (analysis)
• Male
• Manganese (metabolism)
• Mice
• Muscle, Skeletal (drug effects, physiopathology)
• Necrosis
• Neuroblastoma (pathology)
• Neuromuscular Blockade
• Phospholipases A (chemistry, drug effects)
• Phrenic Nerve (drug effects, physiology)
• Sensitivity and Specificity
• Tumor Cells, Cultured