Single calcium channels and their inactivation.

Inactivation of single Ca channels in snail neurons was examined to test the idea that entering Ca ions react directly with the channel to produce this effect. Simulations of specific models were used for comparison with the experimental data. The Ca-dependent model predicts time-dependent changes in the single-channel events which were not found experimentally. It is possible that Ca-dependent inactivation is mediated by a Ca-binding protein that is associated with but not part of the channel itself.