Selectivity and direction: plasma membranes in renal transport.

Studies using isolated renal plasma membranes are now considered to be essential methods for elucidating renal transport processes in health and disease. This review first describes the development of methods and concepts in working with isolated plasma membranes some 20 years ago, when few people believed that it was actually possible to isolate plasma membranes at all. The concepts we developed at that time are still applicable today, and I believe they are therefore worth reiterating. The description of the past leads to a presentation of current ideas about the interrelationship between selectivity of renal plasma membranes and direction of transepithelial transport. Finally, the future direction of kidney research is discussed in view of recent physiological, biochemical, and genetic studies.