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. 1989 Apr;89(4):1184–1192. doi: 10.1104/pp.89.4.1184

Characterization of Potassium-Dependent Currents in Protoplasts of Corn Suspension Cells 1

Karen A Ketchum 1,2, Alvin Shrier 1,2, Ronald J Poole 1,2
PMCID: PMC1055994  PMID: 16666682

Abstract

Protoplasts obtained from corn (Zea mays) suspension cells were studied using the whole cell patch-clamp technique. One time-independent current, as well as two time-dependent currents were identified. All three currents were reduced by tetraethylammonium (9 millimolar), a K+ channel blocker. The time-independent current had a nearly linear current-voltage relationship and its reversal potential, defined as the voltage at which there is zero current, was highly dependent on the extracellular potassium concentration. One of the two time-dependent currents was activated, with rapid kinetics, by membrane hyperpolarization to potentials more negative than −100 millivolts. The second time-dependent current was activated with a sigmoidal time course by membrane depolarization to potentials more positive than −60 millivolts. It exhibited no inactivation and was carried primarily by potassium ions. These characteristics suggest that this latter current is caused by the voltage-dependent opening of delayed-rectifier K+ channels. These three currents, which are not generated by the plasmalemma H+-ATPase, are likely to assist in the regulation of the cellular K+ fluxes and membrane potential.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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