Investigating Ion Channel Distribution Using a Combination of Spatially Limited Photolysis, Ca²⁺ Imaging, and Patch Clamp Recording

Abstract

The production of saliva by parotid acinar cells is stimulated by Ca²⁺ activation of Cl⁻ and K⁺ channels located in the apical plasma membrane of these polarized cells. Here, we utilize a combination of spatially limited flash photolysis, Ca²⁺ imaging, and electrophysiological recording to investigate the distinct distribution of Ca²⁺-dependent ion channels in the plasma membrane (PM) of enzymatically isolated murine parotid acinar cells. In these experiments, the aim of photolysis is to selectively target and modify the activity of ion channels, thereby revealing membrane-domain-specific differences in distribution. Specifically, the relative distribution of channels to either apical or basal PM can be investigated. Since there is substantial evidence that Ca²⁺-dependent Cl⁻ channels are exclusively localized to the apical membrane of acinar cells, this provides an important electrophysiological verification that a particular membrane has been specifically targeted.