EFFECT OF AMMODYTIN-L FROM VIPERA-AMMODYTES ON L-6 CELLS FROM RAT SKELETAL-MUSCLE

Ammodytin L (AMDL) is a myotoxic phospholipase-like protein from the v enom of Vipera ammodytes with a serine in position 49 instead of an as partate, therefore this toxin is devoid of phospholipase activity, and the membrane-damaging effect does not involve any step of phospholipa se activity. The aim of the present study was to analyze the effect of AMDL on L-6 cells from rat skeletal muscle to investigate its mechani sm of action and the role of calcium ions in its muscle-damaging activ ity. Our data indicate that the effect of ammodytin L is strongly depe ndent on the degree of cell differentiation. Low doses of myotoxin gav e rise to a marked release of creatine kinase in myotubes differentiat ed from L-6 myoblasts and the presence of calcium ions plays a role in the cytotoxic effect. The presence of EGTA in the incubation buffer r educed by 50% the release of creatine kinase. No membrane damage was o bserved in myoblasts, but there was a significant increase of intracel lular calcium concentration measured with Fura-2. A non-specific membr ane effect of AMDL was ruled out using platelets as reference cells: n o platelet aggregation pattern and no increase in intracellular calciu m were observed.