Identification of an ATP-sensitive potassium channel current in rat striatal cholinergic interneurones

Whole-cell patch-clamp recordings were made from rat striatal cholinergic interneurones in slices of brain tissue in vitro . In the absence of ATP in the electrode solution, these neurones were found to gradually hyperpolarize through the induction of an outward current at −60 mV. This outward cur...

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Bibliographic Details
Published in:The Journal of physiology 1998-07, Vol.510 (2), p.441-453
Main Authors: Lee, K., Dixon, A. K., Freeman, T. C., Richardson, P. J.
Format: Article
Language:English
Subjects:
Adenosine Triphosphate - physiology
Animals
Diazoxide - pharmacology
Diuretics
Electric Stimulation
Electrophysiology
Glyburide - pharmacology
Hypoglycemic Agents - pharmacology
In Vitro Techniques
Interneurons - metabolism
Male
Membrane Potentials - physiology
Neostriatum - cytology
Neostriatum - metabolism
Original
Parasympathetic Nervous System - cytology
Parasympathetic Nervous System - metabolism
Patch-Clamp Techniques
Potassium Channels - physiology
Rats
Rats, Sprague-Dawley
Reverse Transcriptase Polymerase Chain Reaction
Sodium Chloride Symporter Inhibitors - pharmacology
Tolbutamide - pharmacology
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Summary:Whole-cell patch-clamp recordings were made from rat striatal cholinergic interneurones in slices of brain tissue in vitro . In the absence of ATP in the electrode solution, these neurones were found to gradually hyperpolarize through the induction of an outward current at −60 mV. This outward current and the resultant hyperpolarization were blocked by the sulphonylureas tolbutamide and glibenclamide and by the photorelease of caged ATP within neurones. This ATP-sensitive outward current was not observed when 2 mM ATP was present in the electrode solution. Under these conditions, 500 μM diazoxide was found to induce an outward current that was blocked by tolbutamide. Using permeabilized patch recordings, neurones were shown to hyperpolarize in response to glucose deprivation or metabolic poisoning with sodium azide (NaN 3 ). The resultant hyperpolarization was blocked by tolbutamide. In cell-attached recordings, metabolic inhibition with 1 mM NaN 3 revealed the presence of a tolbutamide-sensitive channel exhibiting a unitary conductance of 44.1 pS. Reverse transcription followed by the polymerase chain reaction using cytoplasm from single cholinergic interneurones demonstrated the expression of the ATP-sensitive potassium (K ATP ) channel subunits Kir6.1 and SUR1 but not Kir6.2 or SUR2. It is concluded that cholinergic interneurones within the rat striatum exhibit a K ATP channel current and that this channel is formed from Kir6.1 and SUR1 subunits.
ISSN:0022-3751
1469-7793
DOI:10.1111/j.1469-7793.1998.441bk.x