ABSTRACT
Ion channels form pores through cell membranes which are permeable to the small physiological ions Na+, K+, Ca2+, and Cl−. The channels can open and close and thereby turn the ux of the charged ions through the cell membrane on and off. By this mechanism, the ion channels govern the fast electrical activity of cells. Additionally, ion channels control Ca2+ inux and regulate responses as diverse as muscle contraction, neuronal signaling, hormone secretion, cell division, and gene expression. Moreover, ion channels are also found in organelles (endoplasmatic reticulum, nucleus, lysosomes, and mitochondria) where they control ion homeostasis and regulate organelle function. The opening of the channels is subject to regulation by physiological stimuli such as changes in membrane
13.1 Introduction .......................................................................................................................... 213 13.1.1 Ion Channels Are Pores through the Cell Membrane .............................................. 214 13.1.2 Ion Currents Change the Electrical Membrane Potential ......................................... 214 13.1.3 Gating of Ion Channels ............................................................................................. 215 13.1.4 Molecular Structures of Ion Channels ...................................................................... 216 13.1.5 Ion Channels and Disease ......................................................................................... 217 13.1.6 Physiological and Pharmacological Modulation of Ion Channels ............................ 217 13.1.7 Drug Screening on Ion Channels.............................................................................. 218 13.1.8 Structure of Voltage-Gated Ion Channels ................................................................ 218
13.2 Physiology and Pharmacology of Voltage-Gated Ion Channels: Potassium Channels ........ 219 13.3 Voltage-Gated Calcium Channels ........................................................................................ 222
13.3.1 Structure and Molecular Biology ............................................................................. 222 13.3.2 Physiological Roles of Voltage-Gated Calcium Channels ........................................ 223 13.3.3 Pharmacology of Voltage-Gated Calcium Channels ................................................224
