Article date: May 1994
By: Paul A. Smith, Beatrice A. Williams, Frances M. Ashcroft, in Volume 112, Issue 1, pages 143-149
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 (KATP‐channels) from mouse isolated pancreatic β‐cells in the absence of ATP and Mg2+.
BDM reversibly inhibited whole‐cell KATP‐currents with a concentration for half maximal inhibition (Ki) of 15 ± 1 mm and a Hill coefficient (n) of 2.5 ± 0.2 (n = 4).
In outside‐out patches, external BDM reversibly reduced the activity of single KATP‐channels with an affinity similar to that observed in whole‐cell recordings (Ki = 11 ± 3 mm, n = 2.0 ± 0.3, n = 7). In inside‐out patches, internally applied BDM also reversibly blocked the activity of KATP‐channels (Ki = 31 ± 2 mm, 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.
BDM had no effect on the single‐channel current amplitude.
The results suggest that BDM blocks the KATP‐channel directly, by mechanisms independent of channel dephosphorylation.
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 (KATP‐channels) from mouse isolated pancreatic β‐cells in the absence of ATP and Mg2+.
BDM reversibly inhibited whole‐cell KATP‐currents with a concentration for half maximal inhibition (Ki) of 15 ± 1 mm and a Hill coefficient (n) of 2.5 ± 0.2 (n = 4).
In outside‐out patches, external BDM reversibly reduced the activity of single KATP‐channels with an affinity similar to that observed in whole‐cell recordings (Ki = 11 ± 3 mm, n = 2.0 ± 0.3, n = 7). In inside‐out patches, internally applied BDM also reversibly blocked the activity of KATP‐channels (Ki = 31 ± 2 mm, 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.
BDM had no effect on the single‐channel current amplitude.
The results suggest that BDM blocks the KATP‐channel directly, by mechanisms independent of channel dephosphorylation.
DOI: 10.1111/j.1476-5381.1994.tb13044.x
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