The Influence of Ca2+and K+on H14CO3−Influx in Internodal Cells of Chara corallina

Abstract

The influences of Ca²⁺-free solutions and increasing K⁺ concentrations on the H¹⁴CO⁻₃ influx capacity of Chara corallina were investigated. It was found that contact with Ca²⁻free solutions resulted in a gradual reduction in the H¹⁴CO⁻₃ influx capacity of these cells. Recovery of this influx capacity, following the return of Ca²⁺ to the experimental solution, followed a ‘mirror-image’ of the time course of decay. Potassium concentrations above a certain critical value (2 mM) induced a rapid reduction in H¹⁴CO⁻₃ influx capacity. Normal activity was recovered within 60–90 min following the return to 0.2 mMK⁺ solutions. It was also shown that 10 mM K⁺ can be used to determine the relative contribution of ¹⁴C supplied by diffusion of ¹⁴CO₂ and transport of H¹⁴CO⁻₃. The Ca²⁺ and K⁺ results are discussed in relation to the effects of these treatments on the electrical properties of the plasmalemma.