Neurochemistry international
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Ouabain is a cardiotonic glycoside that inhibits the sodium potassium ATPase pump leading to sodium accumulation in nerve terminals. At the frog neuromuscular junction, ouabain induces acetylcholine release and a rapid depletion of synaptic vesicles. In the present work, we used FM1-43 vital labeling to dissect the effect of ouabain on synaptic vesicles recycling. ⋯ We observed that muscles incubated with FM1-43 in the presence of ouabain did not present significant staining. In conclusion, our data demonstrate that exocytosis evoked by ouabain is independent on extracellular calcium but dependent on calcium release from endoplasmic reticulum and mitochondrial stores. In addition, we suggest that ouabain can be used as a pharmacological tool to uncouple synaptic vesicles exocytosis from endocytosis at the neuromuscular junction.