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Block of ATP‐sensitive K + channels in isolated mouse pancreatic β‐cells by 2,3‐butanedione monoxime
Author(s) -
Smith Paul A.,
Williams Beatrice A.,
Ashcroft Frances M.
Publication year - 1994
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.1476-5381.1994.tb13044.x
Subject(s) - block (permutation group theory) , chemistry , microbiology and biotechnology , biology , combinatorics , mathematics
1 The patch‐clamp technique has been used to examine the action of the chemical phosphatase 2,3‐butanedione monoxime (BDM) on ATP‐sensitive K + channels (K ATP ‐channels) from mouse isolated pancreatic β‐cells in the absence of ATP and Mg 2+ . 2 BDM reversibly inhibited whole‐cell K ATP ‐currents with a concentration for half maximal inhibition ( K i ) of 15 ± 1 m m and a Hill coefficient (n) of 2.5 ± 0.2 ( n = 4). 3 In outside‐out patches, external BDM reversibly reduced the activity of single K ATP ‐channels with an affinity similar to that observed in whole‐cell recordings ( K i = 11 ± 3 m m , n = 2.0 ± 0.3, n = 7). In inside‐out patches, internally applied BDM also reversibly blocked the activity of K ATP ‐channels ( K i = 31 ± 2 m m , n = 2.2 ± 0.4, n = 8). In both excised patch configurations, BDM decreased the mean open life‐time and the burst duration, thereby producing a decrease in the channel open probability. The drug had no effect on the short intraburst closed times. 4 BDM had no effect on the single‐channel current amplitude. 5 The results suggest that BDM blocks the K ATP ‐channel directly, by mechanisms independent of channel dephosphorylation.