ABSTRACT
This chapter discusses the considered that in nonepithelial cells — specifically, red cells — the responses of various transporters to volume perturbation are in some way coordinated. Lithium-loaded dog red cells showed an increase in the set point volume for Na/H exchange. Replacement of chloride by anions of the lyotropic series, nitrate and thiocyanate, caused a downward shift of the set point volume in dog red cells. A stimulatory effect of hypoxia on monovalent cation permeability of avian red cells was described by Tosteson and Robertson in 1956. The cytosol of red cells contains millimolar concentrations of ATP, plus 2,3-diphosphoglycerate or inositol pentaphosphate. The field of transport regulation was greatly stimulated by the discovery of okadaic acid and its congeners, compounds that freely enter intact cells and inhibit certain serine and threonine protein phosphatases. The Na/H exchanger of dog red cells could be irreversibly activated if, while the cells were shrunken, they were exposed to a low concentration of glutaraldehyde.
