Two components of potassium outward current in smooth muscle cells from the circular layer of human jejunum.
Two components of the outward K+ currents (Ik) of cells isolated from the circular layer of human jejunum were investigated using the conventional whole-cell voltage clamp method. A fast transient Ik component could only be elicited by depolarization in cells dialysed with pipette solution of pCa < 7.4. This Ik component was strongly voltage dependent, and could be selectively abolished by 30 mumol/l quinidine. Its amplitudes decreased in the absence of Ca entry, the decrease depending on the duration of cell exposure to media containing calcium-blockers, and disappeared after depletion of intracellular Ca2+ stores. The steady-state component of Ik was sensitive to tetraethylammonium. This component had comparable amplitudes at pCa = 8.4 or pCa = 7.4 of the pipette solution, and was present during a long-lasting exposure of cells to solutions containing Ca(2+)-blocking drugs.
Duridanova
D B
DB
Institute of Biophysics, Bulgarian Academy of Sciences, Sofia, Bulgaria. dessybd@iph.bio.acad.bg
Gagov
H S
HS
Damyanov
D
D
Boev
K K
KK
D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D004594:Electrophysiology; D006801:Humans; D007583:Jejunum / Q000166:cytology / Q000378:metabolism*; D009130:Muscle, Smooth / Q000166:cytology / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism; D015221:Potassium Channels / Q000502:physiology*
D015221:Potassium Channels; D011188:Potassium; D002118:Calcium