Figure 1.

Typical bioassays illustrating the effects of sulfonylureas and KCOs on stomatal movements in C. communis. (A) A 2.5-h application of sulfonylureas (solid lines) induced a dose-dependent increase in stomatal aperture either in the dark (closed symbols) or under light (open symbols), whereas application of KCOs inhibited stomatal opening under light (dashed lines). (B) KCOs induced stomatal closure under light. Stomata were first illuminated for 3 h and then KCOs were added for a further 2.5 h. Differences in stomatal apertures, observed in absence of KCOs, are not attributable to experimental design but rather to an independent factor such as the annual cycle reported for the pump current by Lohse and Hedrich (27). (C) Stimulation of stomatal opening under illumination by 10 μM glibenclamide (solid line) was prevented by a concomitant application of cromakalim in a dose-dependent manner (○). Conversely, stomatal closure induced by 20 μM cromakalim under illumination (dashed line) was reversed by a concomitant addition of glibenclamide in a dose-dependent manner.