A whole-cell and single-channel study of the voltage-dependent outward potassium current in avian hepatocytes.
Data(s) |
01/02/1988
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Formato |
255 - 274 |
Identificador |
http://www.ncbi.nlm.nih.gov/pubmed/2453605 J Gen Physiol, 1988, 91 (2), pp. 255 - 274 0022-1295 |
Relação |
J Gen Physiol 10.1085/jgp.91.2.255 |
Tipo |
Journal Article |
Cobertura |
United States |
Resumo |
Voltage-dependent membrane currents were studied in dissociated hepatocytes from chick, using the patch-clamp technique. All cells had voltage-dependent outward K+ currents; in 10% of the cells, a fast, transient, tetrodotoxin-sensitive Na+ current was identified. None of the cells had voltage-dependent inward Ca2+ currents. The K+ current activated at a membrane potential of about -10 mV, had a sigmoidal time course, and did not inactivate in 500 ms. The maximum outward conductance was 6.6 +/- 2.4 nS in 18 cells. The reversal potential, estimated from tail current measurements, shifted by 50 mV per 10-fold increase in the external K+ concentration. The current traces were fitted by n2 kinetics with voltage-dependent time constants. Omitting Ca2+ from the external bath or buffering the internal Ca2+ with EGTA did not alter the outward current, which shows that Ca2+-activated K+ currents were not present. 1-5 mM 4-aminopyridine, 0.5-2 mM BaCl2, and 0.1-1 mM CdCl2 reversibly inhibited the current. The block caused by Ba was voltage dependent. Single-channel currents were recorded in cell-attached and outside-out patches. The mean unitary conductance was 7 pS, and the channels displayed bursting kinetics. Thus, avian hepatocytes have a single type of K+ channel belonging to the delayed rectifier class of K+ channels. |
Idioma(s) |
ENG |
Palavras-Chave | #4-Aminopyridine #Aminopyridines #Animals #Calcium #Cells, Cultured #Chickens #Electric Conductivity #Electrophysiology #Ion Channels #Kinetics #Liver #Male #Membrane Potentials #Potassium #Tetrodotoxin |