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Clonidine inhibits ATP‐sensitive K + channels in mouse pancreatic β‐cells
Author(s) -
Plant T.D.,
Jonas JC.,
Henquin J.C.
Publication year - 1991
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1991.tb12440.x
Subject(s) - clonidine , diazoxide , endocrinology , medicine , chemistry , adenosine , membrane potential , agonist , biophysics , patch clamp , adenosine triphosphate , biology , electrophysiology , biochemistry , insulin , receptor
1 The effects of clonidine and adrenaline on adenosine 5′‐triphosphate (ATP)‐sensitive K + channels were studied in pancreatic β‐cells from normal mice. 2 When perifused with a medium containing 1 m m glucose, many of the ATP‐sensitive K + channels in the β‐cell membrane are open. Under these conditions, clonidine (5–100 μ m ) reversibly decreased 86 Rb efflux from the islets, whereas adrenaline was ineffective at concentrations up to 100 μ m . 3 In 6 m m glucose, most of the ATP‐sensitive K + channels in the β‐cell membrane are closed. Opening these channels by diazoxide (100 μ m ) caused a marked acceleration of 86 Rb efflux from the islets, which was attenuated by 100 μ m clonidine. 4 ATP‐sensitive K + currents were measured in single β‐cells by the whole cell mode of the patch‐clamp technique. At concentrations above 4 μ m , clonidine reversibly inhibited the ATP‐sensitive K + current in a dose‐dependent manner. 5 Voltage‐sensitive K + currents were unaffected by 20 μ m but decreased slightly by 100 μ m clonidine. 6 Calcium currents, measured by the whole cell or perforated patch technique, were unaffected by clonidine at concentrations up to 100 μ m . 7 It is concluded that high concentrations of the α 2 ‐adrenoceptor agonist clonidine, but not of adrenaline, can inhibit ATP‐sensitive K + channels in pancreatic β‐cells. Other ionic channels are only slightly affected or unaffected.