Enhanced net K+ uptake capacity of NaCl-adapted cells

Abstract

Maintenance of intracellular K+ concentrations that are not growth-limiting, in an environment of high Na+, is characteristic of NaCl-adapted cells of the glycophyte, tobacco (Nicotiana tabacum/gossii). These cells exhibited a substantially greater uptake of 86Rb+ (i.e. an indicator of K+) relative to unadapted cells. Potassium uptake into NaCl-adapted cells was 1.5-fold greater than unadapted cells at 0 NaCl and 3.5-fold greater when cells were exposed to 160 millimolar NaCl. The difference in net K+ uptake between unadapted and NaCl-adapted cells was due primarily to higher rates of entry rather than to reduced K+ leakage. Presumably, enhanced K+ uptake into adapted cells is a result of electrophoretic flux, and a component of uptake may be linked to vanadate-sensitive H+ extrusion.