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 increa sed the rate of spontaneous [H-3]-ACh release. In brain cortical slice s La3+ did not affect the spontaneous release of ACh. The release of A Ch induced by tityustoxin, ouabain or K+ 50 mM in brain cortex and mye nteric longtudinal muscles slices was inhibited by La3+ treatment. It is suggested that tityustoxin, ouabain and K+ release ACh from the sam e pool that is inhibited by La3+ pretreatment.