Biophysical and pharmacological properties of the voltage-gated potassium current of human pancreatic beta-cells

J Physiol. 2005 Aug 15;567(Pt 1):159-75. doi: 10.1113/jphysiol.2005.089375. Epub 2005 Jun 2.


Voltage-gated potassium (Kv) currents of human pancreatic islet cells were studied by whole-cell patch clamp recording. On average, 75% of the cells tested were identified as beta-cells by single cell, post-recording RT-PCR for insulin mRNA. In most cells, the dominant Kv current was a delayed rectifier. The delayed rectifier activated at potentials above -20 mV and had a V(1/2) for activation of -5.3 mV. Onset of inactivation was slow for a major component (tau = 3.2 s at +20 mV) observed in all cells; a smaller component (tau = 0.30 s) with an amplitude of approximately 25% was seen in some cells. Recovery from inactivation had a tau of 2.5 s at -80 mV and steady-state inactivation had a V(1/2) of -39 mV. In 12% of cells (21/182) a low-threshold, transient Kv current (A-current) was present. The A-current activated at membrane potentials above -40 mV, inactivated with a time constant of 18.5 ms at -20 mV, and had a V(1/2) for steady-state inactivation of -52 mV. TEA inhibited total Kv current with an IC50 = 0.54 mm and PAC, a disubstituted cyclohexyl Kv channel inhibitor, inhibited with an IC50 = 0.57 microm. The total Kv current was insensitive to margatoxin (100 nm), agitoxin-2 (50 nm), kaliotoxin (50 nm) and ShK (50 nm). Hanatoxin (100 nm) inhibited total Kv current by 65% at +20 mV. Taken together, these data provide evidence of at least two distinct types of Kv channels in human pancreatic beta-cells and suggest that more than one type of Kv channel may be involved in the regulation of glucose-dependent insulin secretion.

MeSH terms

  • Biophysical Phenomena
  • Biophysics
  • Cells, Cultured
  • Cyclohexanones / pharmacology
  • Delayed Rectifier Potassium Channels
  • Humans
  • Islets of Langerhans / cytology
  • Islets of Langerhans / physiology*
  • Membrane Potentials / drug effects
  • Membrane Potentials / physiology
  • Neurotoxins / pharmacology
  • Patch-Clamp Techniques
  • Peptides / pharmacology
  • Potassium Channel Blockers / pharmacology*
  • Potassium Channels, Voltage-Gated / physiology*
  • Scorpion Venoms
  • Tetraethylammonium / pharmacology*


  • 4-phenyl-4-(3-(2-methoxyphenyl)-3-oxo-2-azaprop-1-yl)cyclohexanone
  • Cyclohexanones
  • Delayed Rectifier Potassium Channels
  • Neurotoxins
  • Peptides
  • Potassium Channel Blockers
  • Potassium Channels, Voltage-Gated
  • Scorpion Venoms
  • hanatoxin
  • margatoxin
  • Tetraethylammonium