• K+;
  • malate;
  • Phaseolus coccineus;
  • pulvinus


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.