The influence of small applied electrical currents on Na, K, and Cl fluxes in Nitella translucens

Abstract

The changes of influx and efflux of Na, K, and Cl were studied in Nitella in artificial pond water (APW) under varying current densities below 1.3 μamp cm−2. The electric current seemed to act only on the passive ion influx and K efflux. Cl influx was insensitive to applied current. Na influx normally carried about 1/5 of the current, K much less unless the K concentration of the APW was increased. The relative percentage of each ion carrying the current at the positive end of the cell was readily altered by changes in K concentration or pH. It is presumed that H ion is also involved. In our experiments, low current densities below 0.7 μamp cm−2 gave no detectable effect on K, Na, or Cl effluxes at either end of the cell. Thus in electroosmotic experiments, Na influx at the positive end of the cell is an important flux, while K efflux is important at the negative end.Microinjection of tracer into the vacuole of Nitella is a feasible technique. Once isotopes have penetrated the cell membrane, they seem to move to some extent independently of each other.