This book draws together contributions from basic, pharmaceutical and clinical sciences aimed at a better understanding of the structure and function of hERG and the molecular basis for compound binding. It features regulatory authority perspectives on preferred preclinical test systems and includes topics on hERG channel gating, regulation of functional expression, pharmacological properties of hERG/IKr channels, drug-induced long QT syndrome and preclinical evaluation and regulatory recommendations for assessing QT prolongation risks. Better understanding of the role of the hERG channe