Activation of high affinity Cl⁻ transport following shift from 40 mM Cl⁻ to low Cl⁻ medium. (A) Cells (sul1) were grown overnight in LCAPG with no added Cl⁻ (∼0.005 mM; •) or 40 mM added NaCl (▴), and then washed twice in cold LCAPG, resuspended in LCAPG, pH 4.5, 30°C, with 8 μM Na³⁶Cl, and the accumulation of ³⁶Cl⁻ measured over the next 50 min. (B) Cells (sul1) were grown in APG + 40 mM NaCl, washed twice in cold LCAPG, and suspended at t = 0 in LCAPG, pH 4.5, 30°C. At the indicated times, 8 μM Na³⁶Cl was added and the tracer influx measured for 1 min. Data are from two separate cell preparations.