HCO3 Influx Across the Plasmalemma of Chara corallina

Abstract
An absolute requirement for divalent cations is reported for H14CO3 influx in Chara corallina. Effective substitution of eluted Ca2+ by Mg2+ and Sr2+ was observed, but Mn2+ was completely ineffective in restoring H14CO3 transport activity. Similarly, La3+ could not substitute for Ca2+ in this system. Low concentrations of ethylenediaminetetraacetate (0.01 to 0.06 mm) significantly enhanced the rate at which H14CO3 transport capacity was lost.