Cells maintain uneven distribution of Na, K and Ca ions across the cell membrane and membranes of intracellular organellae. Cells exert their functions by allowing for some ion to cross the membrane through ion channels which either produces an electrical effect across the membrane or switches on a series of chemical or physicochemical reactions. This is a comprehensive book about these vitally important ion channels with detailed description of the molecular structure and function and especially of activators and inhibitors. All chapters are written by renowned specialists in their field.