Characterisation of large-conductance calcium-activated potassium channels (BK(Ca)) in human NT2-N cells
| Autor: | Peter W. Andrews, Hugh Chapman, C. Piggot, Kenneth Taylor Wann |
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| Rok vydání: | 2006 |
| Předmět: |
Time Factors
Potassium chemistry.chemical_element Membrane Potentials chemistry.chemical_compound symbols.namesake Adenosine Triphosphate Cell Line Tumor Potassium Channel Blockers Reaction Time Humans Patch clamp Calcium Signaling Large-Conductance Calcium-Activated Potassium Channels Paxilline Molecular Biology Neurons Hill differential equation Dose-Response Relationship Drug General Neuroscience Cell Membrane Time constant Conductance Calcium-activated potassium channel Potassium channel chemistry Biochemistry Biophysics symbols Calcium Neurology (clinical) Ion Channel Gating Developmental Biology |
| Zdroj: | Brain research. 1129(1) |
| ISSN: | 0006-8993 |
| Popis: | Large-conductance calcium-activated potassium (BK(Ca)) channels were studied in inside-out patches of human NTERA2 neuronal cells (NT2-N). In symmetrical (140 mM) K(+) the channel mean conductance was 265 pS, the current reversing at approximately 0 mV. It was selective (P(K)/P(Na)=20:1) and blocked by internal paxilline and TEA. The open probability-voltage relationship for BK(Ca) was fitted with a Boltzmann function, the V((1/2)) being 76.3 mV, 33.6 mV and -14.1 mV at 0.1 muM, 3.3 muM and 10 muM [Ca(2+)](i), respectively. The relationship between open probability and [Ca(2+)](i) was fitted by the Hill equation (Hill coefficient 2.7, half maximal activation at 2.0 muM [Ca(2+)](i)). Open and closed dwell time histograms were fitted by the sum of two and three voltage-dependent exponentials, respectively. Increasing [Ca(2+)](i) produced both an increase in the longer open time constant and a decrease in the longest closed time constant, so increasing mean open time. "Intracellular" ATP evoked a concentration-dependent increase in NT2-N BK(Ca) activity. At +40 mV half-maximum activation occurred at an [ATP](i) of 3 mM (30 nM [Ca(2+)](i)). ADP and GTP were less potent, and AMP-PNP was inactive. This is the first characterisation of a potassium channel in NT2-N cells showing that it is similar to the BK(Ca) channel of other preparations. |
| Databáze: | OpenAIRE |
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