The effect of tityustoxin and ruthenium red on the release of acetylcholine from slices of cortex of rat brain.

The effect of tityustoxin and ruthenium red on the release of acetylcholine from slices of cortex from the brain of the rat was studied. The results showed that ruthenium red stimulated the elicited release of acetylcholine (ACh) by tityustoxin. The effect was dependent on the incubation time and the concentration of ruthenium red. The stimulation was dependent on calcium and was blocked by the presence of tetrodotoxin and ethyleneglycol-bis(beta aminoethyl ether)N,N'-tetraacetic acid (EGTA). It is suggested that the inhibition of buffering by calcium in mitochondria, by ruthenium red increased the level of ionized calcium in the symaptoplasm, causing an increase in the release of acetylcholine.