Lanthanum Ions abolish the “Calcium Response” of Nerve Terminals

Abstract

IT is well established that, in order to release transmitter, nerve impulses arriving at the terminals require the presence of calcium ions in the external medium¹. In the search for other ions which might replace calcium in the process of transmitter release at the neuromuscular junction, it has been found^2,3 that lanthanum not only failed to substitute for calcium, but blocked transmission when added to a solution containing the normal amount of calcium. In these conditions, impulses still invade the nerve terminals but fail to release transmitter. It was thought that lanthanum might prevent calcium from crossing the nerve membrane and partaking in the subsequent reactions which lead to transmitter release.