Glucagon Induces Suppression of ATP-sensitive K + Channel Activity Through a Ca 2+ /Calmodulin-dependent Pathway in Mouse Pancreatic β-Cells

1998 ◽  
Vol 166 (3) ◽  
pp. 237-244 ◽  
Author(s):  
L.P. He ◽  
D. Mears ◽  
I. Atwater ◽  
H. Kitasato
Keyword(s):  
K Channel ◽  
Channel Activity ◽  
Β Cells ◽  
Pancreatic Β Cells ◽  
Dependent Pathway

scholarly journals Metabolic inhibition impairs ATP-sensitive K+ channel block by sulfonylurea in pancreatic β-cells

1998 ◽  
Vol 274 (1) ◽  
pp. E38-E44 ◽  
Author(s):  
Eri Mukai ◽  
Hitoshi Ishida ◽  
Seika Kato ◽  
Yoshiyuki Tsuura ◽  
Shimpei Fujimoto ◽  
...  
Keyword(s):  
Metabolic Inhibition ◽  
K Channel ◽  
High Dose ◽  
Dependent Manner ◽  
Channel Activity ◽  
Β Cells ◽  
Pancreatic Β Cells ◽  
Patch Clamp Technique ◽  
Channel Inhibition ◽  
Dose Dependent

The effect of metabolic inhibition on the blocking of β-cell ATP-sensitive K+ channels (KATP channels) by glibenclamide was investigated using a patch-clamp technique. Inhibition of KATP channels by glibenclamide was attenuated in the cell-attached mode under metabolic inhibition induced by 2,4-dinitrophenol. Under a low concentration (0.1 μM) of ATP applied in the inside-out mode, KATP channel activity was not fully abolished, even when a high dose of glibenclamide was applied, in contrast to the dose-dependent and complete KATP channel inhibition under 10 μM ATP. On the other hand, cibenzoline, a class Ia antiarrhythmic agent, inhibits KATP channel activity in a dose-dependent manner and completely blocks it, even under metabolic inhibition. In sulfonylurea receptor (SUR1)- and inward rectifier K+ channel (Kir6.2)-expressed proteins, cibenzoline binds directly to Kir6.2, unlike glibenclamide. Thus, KATPchannel inhibition by glibenclamide is impaired under the condition of decreased intracellular ATP in pancreatic β-cells, probably because of a defect in signal transmission between SUR1 and Kir6.2 downstream of the site of sulfonylurea binding to SUR1.

cAMP-independent decrease of ATP-sensitive K+ channel activity by GLP-1 in rat pancreatic β-cells

2000 ◽  
Vol 440 (4) ◽  
pp. 566-572 ◽  
Author(s):  
Sechiko Suga ◽  
Takahiro Kanno ◽  
Yoshiji Ogawa ◽  
Teruko Takeo ◽  
Noritaka Kamimura ◽  
...  
Keyword(s):  
K Channel ◽  
Channel Activity ◽  
Β Cells ◽  
Pancreatic Β Cells

scholarly journals Intracellular Ca2+ Modulation of ATP-Sensitive K+ Channel Activity in Acetylcholine-Induced Activation of Rat Pancreatic β-Cells

Endocrinology ◽  
2002 ◽  
Vol 143 (2) ◽  
pp. 569-576 ◽  
Author(s):  
Kyoko Nakano ◽  
Sechiko Suga ◽  
Teruko Takeo ◽  
Yoshiji Ogawa ◽  
Toshihiro Suda ◽  
...  
Keyword(s):  
K Channel ◽  
Channel Activity ◽  
Β Cells ◽  
Pancreatic Β Cells

ATP Sensitivity of the ATP-Sensitive K+Channel in Intact and Permeabilized Pancreatic β-Cells

Diabetes ◽  
2006 ◽  
Vol 55 (9) ◽  
pp. 2446-2454 ◽  
Author(s):  
Andrei I. Tarasov ◽  
Christophe A.J. Girard ◽  
Frances M. Ashcroft
Keyword(s):  
K Channel ◽  
Β Cells ◽  
Pancreatic Β Cells

Dietary K intake regulates the response of apical K channels to adenosine in the thick ascending limb

2004 ◽  
Vol 287 (5) ◽  
pp. F954-F959 ◽  
Author(s):  
Dimin Li ◽  
Yuan Wei ◽  
Wen-Hui Wang
Keyword(s):  
Adenosine Receptor ◽  
K Channel ◽  
Thick Ascending Limb ◽  
Channel Activity ◽  
Patch Clamp Technique ◽  
Open Probability ◽  
Cgs 21680 ◽  
Adenosine Receptor Agonist ◽  
Dependent Pathway ◽  
Adenosine Analog

We used the patch-clamp technique to study the effect of adenosine on the apical 70-pS K channel in the thick ascending limb (TAL) of the rat kidney. Application of 1 μM cyclohexyladenosine (CHA), an adenosine analog, stimulated apical 70-pS K channel activity and increased the product of channel open probability and channel number ( NPo) from 0.34 to 0.7. Also, addition of CGS-21680, a specific A2a adenosine receptor agonist, mimicked the effect of CHA and increased NPo from 0.33 to 0.77. The stimulatory effect of CHA and CGS-21680 was completely blocked by H89, an inhibitor of protein kinase A (PKA), or by inhibition of adenylate cyclase with SQ-22536. This suggests that the stimulatory effect of adenosine analogs is mediated by a PKA-dependent pathway. The effect of adenosine analog was almost absent in the TAL from rats on a K-deficient (KD) diet for 7 days. Application of DDMS, an agent that inhibits cytochrome P-450 hydrolase, not only significantly increased the activity of the 70-pS K channel but also restored the stimulatory effect of CHA on the 70-pS K channel in the TAL from rats on a KD diet. Also, the effect of CHA was absent in the presence of 20-HETE. Inhibition of PKA blocked the stimulatory effect of CHA on the apical 70-pS K channel in the presence of DDMS in the TAL from rats on a KD diet. We conclude that stimulation of adenosine receptor increases the apical 70-pS K channel activity via a PKA-dependent pathway and that the effect of adenosine on the apical 70-pS K channel is suppressed by low-K intake. Moreover, the diminished response to adenosine is the result of increase in 20-HETE formation, which inhibits the cAMP-dependent pathway in the TAL from rats on a KD diet.

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