Basolateral Potassium Channel Noise: Signals from the Dark Side

This chapter reviews the applications and contributions of current fluctuation analysis to the study of K channels in the basolateral membranes of epithelial cells. It has become increasingly apparent that the basolateral membrane plays a pivotal role in the regulation of transepithelial ion transport. For both absorptive and secretory epithelia, there is now abundant evidence that alterations in salt transport can be accompanied by changes in the conductance of the basolateral membrane to potassium. The chapter discusses experimental difficulties that arise from two sources: the relative inaccessibility of the basolateral side of epithelial cells and the existence of multiple K channel types. These difficulties make noise analysis a particularly appropriate device for “listening” to basolateral K channels. The chapter considers some of the experimental strategies that have been employed to gain access to the basolateral membrane, and compares estimates of K channel blocker kinetics gained from noise analysis with those obtained from single channel recordings.