Extracellular calcium affects the membrane currents of cultured human keratinocytes.
Electrophysiologic properties of cultured human keratinocytes were studied using the patch voltage-clamp technique. Undifferentiated, proliferative keratinocytes grown in low Ca2+ medium had an average resting membrane potential of -24 mV. Voltage-clamp experiments showed that these cells had two membrane ionic currents: a large voltage-independent leak conductance, and a smaller voltage-dependent Cl- current that activated with depolarization. Increasing the extracellular Ca2+ concentration from 0.15 to 2 mM resulted in a doubling of the magnitude of the voltage-gated current and a shift in current activation to more negative potentials. Since levels of extracellular Ca2+ can alter the morphology and differentiation state of keratinocytes, the finding of a Ca2(+)-activated Cl- current in these cells suggests a role for this conductance in the initiation of differentiation.
Department of Dermatology School of Medicine, University of California, Davis 95616.
T M
TM
Mauro
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Pappone
R R
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Isseroff
D002118:Calcium / Q000502:physiology*; D002712:Chlorides / Q000502:physiology; D004553:Electric Conductivity; D004594:Electrophysiology; D005110:Extracellular Space / Q000502:physiology; D006801:Humans; D066298:In Vitro Techniques; D007231:Infant, Newborn; D007473:Ion Channels / Q000502:physiology*; D015603:Keratinocytes / Q000502:physiology*; D008297:Male; D008564:Membrane Potentials
D002712:Chlorides; D007473:Ion Channels; D002118:Calcium