Calcium-channel subtypes in the somata and axon terminals of magnocellular neurosecretory cells.

To understand the specific functions of Ca(2+)-channel types it is necessary to know how they are distributed within neurons. The unique structure of the magnocellular neurosecretory cells of the rat supraoptic nucleus has made it possible to obtain whole-cell recordings from individual somata and axon terminals acutely isolated from adult rats. Characterization of elicited Ca2+ currents in these cells has demonstrated that certain types are segregated in somata or axon terminals, and that current types defined pharmacologically can display different kinetic properties in the two loci. Observed biophysical properties correlate with functional requirements in the two compartments and have implications for the roles of specific Ca(2+)-channel subtypes.