Ion Efflux from Pulvinar Cells during Slow Downward Movement of the Petiole of Mimosa pudica L. Induced by Photostimulation.

Change of extracellular ion concentration in the main pulvinus of Mimosa pudica L. during a slow downward movement induced by white light (0.24 mW cm(-2)) was investigated using K(+)- and Cl(-)-selective electrodes and a pH electrode. The photostimulation induced a transient and concurrent efflux of K(+) and Cl(-) from the motor cells and acidification of extracellular pH in the main pulvinus.