Quantitation of the beta-bungarotoxin-induced release of lactate dehydrogenase from cerebrocortical synaptosomes.

Treatment with beta-bungarotoxin for 1 h induces lactate dehydrogenase release from cerebrocortical synaptosomes. The effect is Ca2+-dependent as suggested by the inhibition observed with EGTA. An inhibition of the effect can be also obtained by addition of Sr2+ ions, suggesting that the phospholipase A2 activity associated to the toxin is involved in the efflux of the enzyme. The beta-bungarotoxin-induced release of synaptoplasmic lactate dehydrogenase is a saturable effect, showing a half-maximal effect concentration of 32 nM and a maximal efflux of 25% of the total synaptosomal enzyme as calculated by double-reciprocal plot.