Fig 8.

Time courses of intracellular K⁺ concentration and net flux during exponential growth of Neurospora on limiting potassium. The experiment and measurements were the same as those described for Fig. 3. (A) Cell-associated potassium measured and [K⁺]_i calculated as described in Materials and Methods. Smoothed curves were drawn by hand. Different starting values of [K⁺]_i reflect net loss of cellular potassium during the lag phase (−4 to 0 h). Scatter of measured [K⁺]_i values (±1 SD) was ∼20% of the mean value. (B) Implied net fluxes were calculated from the increment of total cellular potassium over each successive 16-min interval along the appropriate smooth curve in panel A and then divided by the average cell mass during the same interval along the corresponding fitted curve in Fig. 3. Positive values represent net influx.