The role of extracellular calcium in the effect of a snake venom Lys49-phospholipase A2 on water transport across epithelial membranes

ACLMT is a Lys49-phospholipase A2 myotoxin isolated from the venom of the Agkistrodon contortrix laticinctus snake. This study investigated the mechanisms involved in effect of ACLMT on membrane water permeability by examining the role of extracellular calcium and strontium in this effect. Water flow across the membrane was gravimetrically measured in bladder sac preparations. The decrease in extracellular calcium promoted a higher response of epithelium to ACLMT, suggesting that the extracellular calcium protects the membrane from the action of the toxin. No alteration in the effect of the toxin on water transport was observed when calcium was replaced by strontium, indicating that this effect is independent of its enzymatic activity. These findings may bring an important contribution towards the comprehension of the mechanisms involved in the effect of Lys49-phospholipase A2 myotoxins on water permeability of epithelial membranes, with implications for the understanding of renal toxicity.