Characterization of Large-Conductance Ca ²⁺-Dependent and -Independent K ⁺ Channels in HaCaT Keratinocytes

Abstract

To characterize ion channels expressed in cell membrane of human keratinocytes, patch-clamp recordings were carried out in HaCaT cells. Two types of large-conductance K⁺ channels (about 250 pS) were measured. One type was activated by micromolar concentrations of intracellular Ca²⁺ ions ([Ca²⁺]_i) and membrane depolarization, the other was [Ca²⁺]_i independent. The channels were neither dependent on intracellular ATP nor Mg²⁺ nor on membrane stretch. We conclude that HaCaT keratinocytes express Ca²⁺-dependent maxi K⁺ channels and still unknown large Ca²⁺-independent K⁺ channels. These K⁺ channels may affect the proliferation and differentiation of human keratinocytes by the influence on the resting potential, which may control the Ca²⁺ influx across the cell membrane.