Aquaporins in health and disease

The molecular basis of membrane water-permeability remained elusive until t he recent discovery of the aquaporin water-channel proteins. The fundamenta l importance of these proteins is suggested by their conservation from bact eria through plants to mammals, Ten mammalian aquaporins have thus far been identified, each with a distinct distribution. In the kidney, lung, eye an d brain, multiple water-channel homologs are expressed, providing a network for water transport in those locations. It is increasingly clear that alte rations in aquaporin expression or function can be rate-limiting for water transport across certain membranes, Aquaporins are likely to prove central to the pathophysiology of a variety of clinical conditions from diabetes in sipidus to various forms of edema and, ultimately, they could be a target f or therapy in diseases of altered water homeostasis.