Ferret red cells: Na/Ca exchange and Na-K-Cl cotransport.

The primary pathway for K influx in ferret red cells is the Na-K-Cl cotransporter and the primary pathway for Ca influx is the Na/Ca exchanger. This makes ferret red cells favorable models for the study of these two transport systems. The evidence that Na/Ca exchange is of primary importance for steady state cell volume regulation and the Na-K-Cl cotransport has a minor role is presented. The approaches to, and results of, the determination of the stoichiometry, of the mechanism, and of the regulation by ATP and Mg, for Na/Ca exchange is contrasted with that taken for Na-K-Cl cotransport.