Influence of a potassium‐channel blocker and metabolic and ATPase inhibitors on potassium and malate content of Phaseolus coccineus L. pulvini

Abstract

The effect of the K+ channel blocker tetraethylammonium chloride (TEA‐C1), of non‐specific ATPase inhibitors (dicyclohexylcarbodiimide and diethylstilbestrol) and of the uncoupler, carbonyl cyanide‐m‐chloro‐phenyl‐hydrazone (CCCP) on the contents of K+ and malate was investigated in the intact motor system of Phaseolus coccineus pulvini. The results suggest that in these conditions the activity of K+‐channels in motor cells of extensor and flexor parts is limited. Treatment of detached leaves with 20 mol m−3 TEA‐C1 completely blocked K+ and malate movement and also limited the K+ flux between the opposite parts of the pulvinus. In these conditions K+ and malate contents in the two parts of the pulvinus was reduced in both phases of the diurnal cycle as compared with the control (plants treated with potassium iminodiacetate). A similar effect was found when the activity of the proton pump was decreased by H+‐ATPase inhibitors or CCCP. The transport of potassium and the effect of its content on the level of malate in motor cells of Phaseolus coccineus pulvinus were also investigated. Copyright © 1990, Wiley Blackwell. All rights reserved