The mechanisms and physiological functions of urea transport across biological membranes are subjects of long-standing interest. Recent advances in the molecular biology and physiology of urea transport have yielded new insights into how and why urea moves across cell membranes. In the last two decades, seven facilitated urea transporters (UT-A1-6 and UT-B) have been cloned, and their gene organization, protein crystal structure, expression localization and physiological functions in the tissues have been described. In recent years, the studies in urea transporter knockout mouse models suggest that urea transporters may be useful targets for drug discovery of selective inhibitors. The modulation of urea transport activity by pharmacological agents may provide novel treatments for hypertension, congestive heart failure and other fluid-retaining states. However, although urea represents about 40% of all urinary solutes in normal human urine, the handling of this solute in the tissues has been largely neglected in the past, and few clinical or experimental studies now report data about urea. Most recent physiological textbooks include chapters on water and electrolyte physiology but not a single chapter on urea. Our aim in writing this book is to stimulate further research in new directions by providing novel and provocative insights into further mechanisms and the physiological significance of urea metabolism and transport in mammals. The book provides a state-of-the-art report on the latest findings on urea transport and where the field is going. Although some older work is cited, the main focus is on advances made over the past 20 years with regard to the biophysics, genetics, protein structure, molecular biology, physiology, pathophysiology and pharmacology of urea transport in mammalian cell membranes. These aspects are especially valid, as advances in our understanding of urea transporting mechanisms and physiology promise to yield new insights intobiology and medicine.

Autorentext

Baoxue Yang is a professor and vice chairman of Department of Pharmacology, Peking University. He is also an adjunct professor of Jilin University and a visiting professor of Northeast Normal University. Prof. Yang has been studying on urea transporter for nearly 20 years and published more than 70 original research articles in this field.

Jeff M. Sands is the Juha P. Kokko Professor of Medicine and Physiology, Director of the Renal Division, and Executive Vice-Chair of the Department of Medicine at Emory Universtiy School of Medicine. Dr. Sands' research focuses on urea transport proteins and the urine concentrating mechanisms.

Zusammenfassung
The mechanisms and physiological functions of urea transporters across biological membranes are subjects of long-standing interests. Although urea represents roughly 40% of all urinary solutes in normal human urine, the handling of urea in the tissues has been largely neglected in the past and few clinical or experimental studies now report data on urea. Most recent physiological text books include chapters on water and electrolyte physiology but no chapter on urea. Our aim in writing this book is to stimulate further research in new directions by providing novel and provocative insights into the further mechanisms and physiological significance of urea metabolism and transport in mammals. This book offers a state-of-the-art report on recent discoveries concerning urea transport and where the field is going. It mainly focuses on advances made over the past 20 years on the biophysics, genetics, protein structure, molecular biology, physiology, pathophysiology and pharmacology of urea transport in mammalian cell membranes. It will help graduate students and researchers to get an overall picture of mammalian urea transporters and may also yield benefits for pharmaceutical companies with regard to drug discovery based on the urea transporter. Baoxue Yang is a professor and vice chairman of the Department of Pharmacology, Peking University. He is also an adjunct professor of Jilin University and a visiting professor of Northeast Normal University. Prof. Yang has been researching urea transporters for nearly 20 years and has published more than 70 original research articles in this field.

Inhalt
Overview and Historical Perspective.- Urea.- Mathematical Modeling of Urea Transport in the Kidney.- Genes and Proteins of Urea Transporters.- Structure of urea transporters.- Expression of Urea transporters and Their Regulation.- Biochemical Properties of Urea Transporters.- Transport Characteristics of Urea Transporter-B.- Urea Transporter Knockout Mice and Their Renal Phenotypes.- Extrarenal phenotypes of UT-B knockout mouse.- Small Molecule Inhibitors of Urea Transporters.- Clinical Aspect of Urea Transporters.- Active Urea Transport in Lower Vertebrates and Mammals.- Urea transport Mediated by Aquaporin Water Channel Proteins