Whole-cell K+ currents across the plasma membrane of tobacco protoplasts from cell-suspension cultures

• Published in: Plant physiology (Bethesda) Vol. 101; no. 1; pp. 81 - 88
• Main Authors: Duijn, B. van (Leiden University, Leiden, The Netherlands), Ypey, D.L, Libbenga, K.R
• Format: Journal Article
• Language: English
• Published: Rockville, MD American Society of Plant Physiologists 01-01-1993
• Subjects: Agronomy. Soil science and plant productions; Bioenergetics; Biological and medical sciences; Biotechnology; Cell membranes; Cell physiology; CULTIVO DE CELULAS; CULTURE DE CELLULE; Electric current; Electric potential; ESTRUCTURA CELULAR; Fundamental and applied biological sciences. Psychology; Guard cells; ION; Ion channels; IONES; NICOTIANA TABACUM; Pipettes; Plant cells; Plant physiology and development; Plants; Plasma currents; Plasma membrane and permeation; POTASIO; POTASSIUM; PROTOPLASTE; PROTOPLASTOS; Protoplasts; STRUCTURE CELLULAIRE; Cell culture; Stimulant plant; Patch clamp method; Ionic current; Nicotiana tabacum; Depolarization; Suspension culture; Investigation method; Dicotyledones; Protoplast; Angiospermae; Plasma membrane; Spermatophyta; Solanaceae; Membrane potential; Potassium
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.101.1.81

The whole-cell configuration of the patch clamp technique was used to study both outward and inward ion currents across the plasma membrane of tobacco (Nicotiana tabacum) protoplasts from cell-suspension cultures. The ion currents across the plasma membrane were analyzed by the application of stepwise potential changes from a holding potential or voltage ramps. In all protoplasts, a voltage- and time-dependent outward rectifying current was present. The conductance increased upon depolarization of the membrane potential (to 0 mV) with a sigmoidal time course. The reversal potential of the outward current shifted in the direction of the K+ equilibrium potential upon changing the external K+ concentration. The outward current did not show inactivation. In addition to the outward rectifying current, in about 30% of the protoplasts, a time- and voltage-dependent inward rectifying current was present as well. The inward rectifying current activated upon hyperpolarization of the membrane potential (-1OO mV) with an exponential time course. The reversal potential of the inward conductance under different ionic conditions was close to the K+ equilibrium potential