Effect of lanthanum ions on the release of acetylcholine induced by tityustoxin, K+ and ouabain from myenteric plexus and brain cortical slices.

Exposure of myenteric plexus longitudinal muscles to 2 mM LaCl3 increased the rate of spontaneous [3H]-ACh release. In brain cortical slices La3+ did not affect the spontaneous release of ACh. The release of ACh induced by tityustoxin, ouabain or K+ 50 mM in brain cortex and myenteric longitudinal muscles slices was inhibited by La3+ treatment. It is suggested that tityustoxin, ouabain and K+ release ACh from the same pool that is inhibited by La3+ pretreatment.