Figure 2.

Effect of PAO on the rate of loss of ⁸⁶Rb⁺ from isolated guard cells; rate of loss of tracer against time of washout. White and black symbols refer to the absence and presence of 25 μM PAO. Each curve shows the means of four replicate strips (SEM of 10–20%). PAO was added at 24 or 42 min of washout in its absence (when tracer is predominantly vacuolar) or was added to the last 30 min of loading and from the start of the washout (when both cytoplasm and vacuole are labeled). Tracer content Q* (pmol·mm⁻²) for the first 24–47 min of efflux was fitted to two exponentials, and the efflux at the plasma membrane was calculated.