The Efflux of Chloride from Cells of Nitella and Chara

The efflux of chloride across the plasmalemma of internodal cells of Nitella translucens and of Clwra australis has been measured under various conditions. It is large in the dark, and is reduced by light and by removal of the chloride ions from the external solution. Typical values for a chloride concentration of 1· 3 mM in the external solution are: light, 0·6 pmole cm-2 sec-t, rising in the dark to about 4·0 pmole cm-2 sec-1 for several hours, and finally steady in the dark at about 2· 5 pmole cm-2 sec-i. It is concluded that these changes are produced by changes in the permeability of the membrane to chloride ions. The two species give very similar results