A Comparison of Potassium and Chloride Uptake by Tradescantia albiflora Leaf Cells at Different KCI Concentrations

Abstract

Light stimulates K+ and Cl- uptake into T. albiflora leaf slices from solutions through which N*2 is bubbled, and not from aerated solutions, at KCl concentrations of 0.5, 5 and 20 mM. The metabolic inhibitors CCCP, DCMU and oligomycin affect K+ and Cl- uptake similarly at each of these KCl concentrations. The results suggest that both K+ and Cl- uptake under all conditions studied are driven by energy derived from a cytoplasmic pool of ATP. In aerobic solutions in the light ATP can be supplied by either oxidative phosphorylation or photophosphorylation while in N*2-bubbled solutions in the light non-cyclic photophosphorylation and possibly oxidative phosphorylation, utilizing photosynthetically evolved O*2, provide ATP. As Cl- uptake appears to be independent of K+ uptake, it is suggested that ion uptake by T. albiflora leaf cells may occur according to a mechanism which has been proposed for other green cells, where K+ and CI- are thought to exchange for H+ and OH- respectively.