This third edition seeks to reflect developments in receptor pharmacology, particularly the use of human recombinant receptor systems in drug design and development. Whereas prior editions focused on the correspondence of animal to human receptor systems, this edition examines drug effects on human receptors obtained by recombinant technology, as well as on physiological natural receptor systems in animals. Two new chapters explain how to produce and use human recombinant receptor systems and discuss the interpretation of data from human recombinant receptor studies. Other chapters describe the use of receptor studies to measure and characterize the biological actions of drugs.