Amperometric analysis of exocytosis at chromaffin cells from genetically distinct mice

Amperometry is a very powerful technique for investigating the role(s) spec ific proteins play in exocytosis at the single-cell level. In this study, a mperometry has been used to investigate possible changes in exocytosis at c hromaffin cells isolated from coloboma and tottering mutant mice. Coloboma mice possess a deletion mutation that encompasses the gene for the presynap tic protein SNAP-25 and tottering mice carry a mutation of the alpha (1A) s ubunit gene, which encodes the pore-forming region of P/Q-type calcium chan nels. Although amperometric data measured from tottering and coloboma cells are not significantly different from that measured at wild-type control ce lls, significant differences are found when groups of wild-type chromaffin cells an analyzed at room temperature and at 37 degreesC. Due to the large variability inherent to amperometric data, it is possible that changes in r elease resulting from some genetic differences cannot be detected. To fully exploit the technical advantages of using mouse chromaffin cells, experime ntal guidelines are described which should maximize changes in release resu lting from genetic differences and increase the likelihood of detecting a c hange in amperometric data. (C) 2001 Elsevier Science B.V. All rights reser ved.