This is the first book to summarize experimental results from the new, rapidly expanding field of research into the calcium channel in cell membrane. Calcium is an ubiquitous messenger of various cellular functions. Its fundamental role in the regulation of cardiac contractions has long been recognized. Drugs counteracting some actions of calcium ions, namely calcium antagonists, have since become essential to research. In the last decade it has been established that calcium ions reach their target intracellular system by passing through specialized calcium channels in the membrane. Recently improved experimental techniques combined with the discovery of highly specific Ca channel ligands have dramatically enlarged our knowledge of the molecular structure and function of such channels. The contributions by leading world specialists shed new light on both basic science and possible clinical implications for cardiovascular pharmacology, endocrinology and neuropharmacology.