Delayed rectifier potassium channels were expressed in the membrane of Xenopus oocytes by injection of rat brain DRK1 (Kv2.1) cRNA, and currents were measured in cell-attached and inside-out patch configurations. In intact cells the current-voltage relationship displayed inward going rectification at potentials > +100 mV. Rectification was abolished by excision of membrane patches into solutions containing no Mg2+ or Na+ ions, but was restored by introducing Mg2+ or Na+ ions into the bath solution. At +50 mV, half-maximum blocking concentrations for Mg2+ and Na+ were 4.8 +/- 2.5 mM (n = 6) and 26 +/- 4 mM (n = 3) respectively. Increasing extracellular potassium concentration reduced the degree of rectification of intact cells. It is concluded that inward going rectification resulting from voltage-dependent block by internal cations can be observed with normally outwardly rectifying DRK1 channels.
Internal Na+ and Mg2+ blockade of DRK1 (Kv2.1) potassium channels expressed in Xenopus oocytes. Inward rectification of a delayed rectifier.
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A N Lopatin, C G Nichols; Internal Na+ and Mg2+ blockade of DRK1 (Kv2.1) potassium channels expressed in Xenopus oocytes. Inward rectification of a delayed rectifier.. J Gen Physiol 1 February 1994; 103 (2): 203–216. doi: https://doi.org/10.1085/jgp.103.2.203
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