A ouabain resistant epithelial cell that protects the wild type in co-cultures.

MDCK cells (epithelioid of renal origin) can be cultured as monolayers that resemble natural epithelia. A mutant of these cells (R-MDCK) can grow in cultures exposed to high doses of ouabain (e.g. 100 microM) because one half of its population of pumps has a negligible affinity for this drug. It can also protect the wild type for at least 86 h in co-cultures exposed to ouabain. This article reviews several possible mechanisms of protection, and suggests that it is due to exchange of Na+ and K+ taking place through gap junctions. These connections though, do not seem to be continuous features, but the cells couple intermittently so that, in a given moment, only 28% of them communicate.