Medizinische Universität Graz - Research portal
Selected Publication:
Groschner, K; Silberberg, SD; Gelband, CH; van Breemen, C.
Ca2(+)-activated K+ channels in airway smooth muscle are inhibited by cytoplasmic adenosine triphosphate.
Pflugers Arch. 1991; 417(5):517-522
Doi: 10.1007/BF00370948
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- Leading authors Med Uni Graz
- Groschner Klaus
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- Abstract:
- Large-conductance Ca2(+)-activated K+ channels were studied in membranes of cultured rabbit airway smooth muscle cells, using the patch-clamp technique. In cell-attached recordings, channel openings were rare and occurred only at very positive potentials. Bradykinin (10 microM), an agonist which releases Ca2+ from the sarcoplasmic reticulum, transiently increased channel activity. The metabolic blocker 2,4-dinitrophenol (20 microM), which lowers cellular adenosine triphosphate (ATP) levels, induced a sustained increase of channel activity in cell-attached patches. In excised patches, these channels had a slope conductance of 155 pS at 0 mV, were activated by depolarization and by increasing the Ca2+ concentration at the cytoplasmic side above 10(-7) mol/l. ATP, applied to the cytoplasmic side of the patches, dose-dependently decreased the channel's open-state probability. An inhibition constant (Ki) of 0.2 mmol/l was found for the ATP-induced inhibition. ATP reduced the Ca2+ sensitivity of the channel, shifting the Ca2+ activation curve to the right and additionally reducing its steepness. Our results demonstrate that cytoplasmic ATP inhibits a large-conductance Ca2(+)-activated K+ channel in airway smooth muscle. This ATP modulation of Ca2(+)-activated K+ channels might serve as an important mechanism linking energy status and the contractile state of the cells.
- Find related publications in this database (using NLM MeSH Indexing)
- Adenosine Triphosphate - physiology
- Animals -
- Bradykinin - pharmacology
- Calcium - physiology
- Cells, Cultured -
- Cytoplasm - physiology
- Electric Conductivity -
- Muscle, Smooth - physiology
- Potassium Channels - physiology
- Rabbits -
- Find related publications in this database (Keywords)
- AIRWAY SMOOTH MUSCLE
- PATCH-CLAMP
- CA2+-ACTIVATED K+ CHANNELS
- ATP SENSITIVITY