Direct inhibition of the pancreatic β-cell ATP-regulated potassium channel by α-ketoisocaproate

Robert Bränström, Suad Efendić, Per Olof Berggren, Olof Larsson

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

The ATP-regulated potassium (K(ATP)) channel plays an essential role in the control of insulin release from the pancreatic β-cell. In the present study we have used the patch-clamp technique to study the direct effects of α-ketoisocaproate on the K(ATP) channel in isolated patches and intact pancreatic β-cells. In excised inside-out patches, the activity of the K(ATP) channel was dose-dependently inhibited by α-ketoisocaproate, half- maximal concentration being approximately 8 mM. The blocking effect of α- ketoisocaproate was fully reversible. Stimulation of channel activity by the addition of ATP/ADP (ratio 1) did not counteract the inhibitory effect of α- ketoisocaproate. In the presence of the metabolic inhibitor sodium azide, α- ketoisocaproate was still able to inhibit single channel activity in excised patches and to block whole cell K(ATP) currents in intact cells. No effect of α-ketoisocaproate could be obtained on either the large or the small conductance Ca2+-regulated K+ channel. Enzymatic treatment of the patches with trypsin prevented the inhibitory effect of α-ketoisocaproate. Based on these observations, it is unlikely that the blocking effect of α- ketoisocaproate is due to an unspecific effect on K+ channel pores. Leucine, the precursor of α-ketoisocaproate, did not affect K(ATP) channel activity in excised patches. Our findings are compatible with the view that α- ketoisocaproate not only affects the β-cell stimulus secretion coupling by generation of ATP but also by direct inhibition of the K(ATP) channel.

Original languageEnglish
Pages (from-to)14113-14118
Number of pages6
JournalJournal of Biological Chemistry
Volume273
Issue number23
DOIs
StatePublished - Jun 5 1998
Externally publishedYes

Fingerprint

Potassium Channels
Adenosine Triphosphate
Sodium Azide
Clamping devices
Patch-Clamp Techniques
Leucine
Adenosine Diphosphate
Trypsin
Potassium
Insulin

ASJC Scopus subject areas

  • Biochemistry

Cite this

Direct inhibition of the pancreatic β-cell ATP-regulated potassium channel by α-ketoisocaproate. / Bränström, Robert; Efendić, Suad; Berggren, Per Olof; Larsson, Olof.

In: Journal of Biological Chemistry, Vol. 273, No. 23, 05.06.1998, p. 14113-14118.

Research output: Contribution to journalArticle

Bränström, Robert ; Efendić, Suad ; Berggren, Per Olof ; Larsson, Olof. / Direct inhibition of the pancreatic β-cell ATP-regulated potassium channel by α-ketoisocaproate. In: Journal of Biological Chemistry. 1998 ; Vol. 273, No. 23. pp. 14113-14118.
@article{b2e1c56468694a81be82520b252ec490,
title = "Direct inhibition of the pancreatic β-cell ATP-regulated potassium channel by α-ketoisocaproate",
abstract = "The ATP-regulated potassium (K(ATP)) channel plays an essential role in the control of insulin release from the pancreatic β-cell. In the present study we have used the patch-clamp technique to study the direct effects of α-ketoisocaproate on the K(ATP) channel in isolated patches and intact pancreatic β-cells. In excised inside-out patches, the activity of the K(ATP) channel was dose-dependently inhibited by α-ketoisocaproate, half- maximal concentration being approximately 8 mM. The blocking effect of α- ketoisocaproate was fully reversible. Stimulation of channel activity by the addition of ATP/ADP (ratio 1) did not counteract the inhibitory effect of α- ketoisocaproate. In the presence of the metabolic inhibitor sodium azide, α- ketoisocaproate was still able to inhibit single channel activity in excised patches and to block whole cell K(ATP) currents in intact cells. No effect of α-ketoisocaproate could be obtained on either the large or the small conductance Ca2+-regulated K+ channel. Enzymatic treatment of the patches with trypsin prevented the inhibitory effect of α-ketoisocaproate. Based on these observations, it is unlikely that the blocking effect of α- ketoisocaproate is due to an unspecific effect on K+ channel pores. Leucine, the precursor of α-ketoisocaproate, did not affect K(ATP) channel activity in excised patches. Our findings are compatible with the view that α- ketoisocaproate not only affects the β-cell stimulus secretion coupling by generation of ATP but also by direct inhibition of the K(ATP) channel.",
author = "Robert Br{\"a}nstr{\"o}m and Suad Efendić and Berggren, {Per Olof} and Olof Larsson",
year = "1998",
month = "6",
day = "5",
doi = "10.1074/jbc.273.23.14113",
language = "English",
volume = "273",
pages = "14113--14118",
journal = "Journal of Biological Chemistry",
issn = "0021-9258",
publisher = "American Society for Biochemistry and Molecular Biology Inc.",
number = "23",

}

TY - JOUR

T1 - Direct inhibition of the pancreatic β-cell ATP-regulated potassium channel by α-ketoisocaproate

AU - Bränström, Robert

AU - Efendić, Suad

AU - Berggren, Per Olof

AU - Larsson, Olof

PY - 1998/6/5

Y1 - 1998/6/5

N2 - The ATP-regulated potassium (K(ATP)) channel plays an essential role in the control of insulin release from the pancreatic β-cell. In the present study we have used the patch-clamp technique to study the direct effects of α-ketoisocaproate on the K(ATP) channel in isolated patches and intact pancreatic β-cells. In excised inside-out patches, the activity of the K(ATP) channel was dose-dependently inhibited by α-ketoisocaproate, half- maximal concentration being approximately 8 mM. The blocking effect of α- ketoisocaproate was fully reversible. Stimulation of channel activity by the addition of ATP/ADP (ratio 1) did not counteract the inhibitory effect of α- ketoisocaproate. In the presence of the metabolic inhibitor sodium azide, α- ketoisocaproate was still able to inhibit single channel activity in excised patches and to block whole cell K(ATP) currents in intact cells. No effect of α-ketoisocaproate could be obtained on either the large or the small conductance Ca2+-regulated K+ channel. Enzymatic treatment of the patches with trypsin prevented the inhibitory effect of α-ketoisocaproate. Based on these observations, it is unlikely that the blocking effect of α- ketoisocaproate is due to an unspecific effect on K+ channel pores. Leucine, the precursor of α-ketoisocaproate, did not affect K(ATP) channel activity in excised patches. Our findings are compatible with the view that α- ketoisocaproate not only affects the β-cell stimulus secretion coupling by generation of ATP but also by direct inhibition of the K(ATP) channel.

AB - The ATP-regulated potassium (K(ATP)) channel plays an essential role in the control of insulin release from the pancreatic β-cell. In the present study we have used the patch-clamp technique to study the direct effects of α-ketoisocaproate on the K(ATP) channel in isolated patches and intact pancreatic β-cells. In excised inside-out patches, the activity of the K(ATP) channel was dose-dependently inhibited by α-ketoisocaproate, half- maximal concentration being approximately 8 mM. The blocking effect of α- ketoisocaproate was fully reversible. Stimulation of channel activity by the addition of ATP/ADP (ratio 1) did not counteract the inhibitory effect of α- ketoisocaproate. In the presence of the metabolic inhibitor sodium azide, α- ketoisocaproate was still able to inhibit single channel activity in excised patches and to block whole cell K(ATP) currents in intact cells. No effect of α-ketoisocaproate could be obtained on either the large or the small conductance Ca2+-regulated K+ channel. Enzymatic treatment of the patches with trypsin prevented the inhibitory effect of α-ketoisocaproate. Based on these observations, it is unlikely that the blocking effect of α- ketoisocaproate is due to an unspecific effect on K+ channel pores. Leucine, the precursor of α-ketoisocaproate, did not affect K(ATP) channel activity in excised patches. Our findings are compatible with the view that α- ketoisocaproate not only affects the β-cell stimulus secretion coupling by generation of ATP but also by direct inhibition of the K(ATP) channel.

UR - http://www.scopus.com/inward/record.url?scp=0032486283&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0032486283&partnerID=8YFLogxK

U2 - 10.1074/jbc.273.23.14113

DO - 10.1074/jbc.273.23.14113

M3 - Article

C2 - 9603910

AN - SCOPUS:0032486283

VL - 273

SP - 14113

EP - 14118

JO - Journal of Biological Chemistry

JF - Journal of Biological Chemistry

SN - 0021-9258

IS - 23

ER -