ATP-sensitive and Ca-activated K channels in vertebrate axons: novel links between metabolism and excitability
✍ Scribed by Peter Jonas; Duk -Su Koh; Knut Kampe; Markus Hermsteiner; Werner Vogel
- Publisher
- Springer
- Year
- 1991
- Tongue
- English
- Weight
- 590 KB
- Volume
- 418
- Category
- Article
- ISSN
- 0031-6768
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✦ Synopsis
Two types of metabolically regulated K channels have been identified for the first time in enzymatically demyelinated fibres of amphibian sciatic nerveusing the patch-clamp technique. A maxi K channel with a single-channel conductance of 132 pS (105 mM K on both sides of the membrane, 15 ~ is activated both by micromolar concentrations of internal Ca and by depolarization. A second type of K channel with a conductance of 44 pS is inhibited by intracellular adenosine 5'-triphosphate (ATP) with a half-maximal inhibitory concentration (ICs0) of 35 ~tM. It is blocked by submicromolar concentrations of external glibenclamide. Both channels are sensitive to external tetraethylammonium chloride (IC~0 = 0.2 mM for the maxi K channel and 4.2 mM for the ATP-sensitive channel). They may be part of a complex feedback system regulating axonal excitability under various metabolic conditions.