Plasmalemmal,voltage-dependent ionic currents from excitable pulvinar motor cells ofMimosa pudica |
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Authors: | Herrade Stoeckel Kenneth Takeda |
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Institution: | (1) Institut de Biologie Moléculaire des Plantes-CNRS UPR406, 67084 Strasbourg, France;(2) Laboratoire de Pharmacologie Cellulaire et Moléculaire-CNRS URA600, Université Louis Pasteur de Strasbourg, B.P. 24, 67401 Illkirch, France |
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Abstract: | Summary Plasmalemmal ionic currents from excitable motor cells of the primary pulvinus ofMimosa pudica were investigated by patch-clamp techniques. In almost all of the enzymatically isolated protoplasts, a delayed rectifier potassium current was activated by depolarization, while no currents were detected upon hyperpolarization. This sustained outward current was reversibly blocked by Ba and TEA and serves to repolarize the membrane potential. Outward single channel currents that very likely underly the macroscopic outward potassium current had an elementary conductance of 20 pS. In addition, in a few protoplasts held at hyperpolarized potentials, depolarization-activated transient inward currents were observed, and under current clamp, action potential-like responses were triggered by depolarizing current injections or by mechanical perturbations. The activation characteristics of both inward currents and spikes showed striking similarities compared to those of action potentialsin situ. |
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Keywords: | delayed rectifier potassium current action potential Mimosa pulvinar motor cells plasmalemma patch clamp |
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