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Uncoupling by (-)-epigallocatechine-3-gallate of ATP-sensitive potassium channels from phosphatidylinositol polyphosphates and ATP

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Author(s)
Jun-Yup JinSung-Hee ParkJae-Hoon BaeHo-Chan ChoJeong-Geun LimWon Sun ParkJin HanJin Ho LeeDae-Kyu Song
Keimyung Author(s)
Bae, Jae HoonSong, Dae KyuLim, Jeong GeunCho, Ho Chan
Department
Dept. of Physiology (생리학)
Dept. of Neurology (신경과학)
Dept. of Internal Medicine (내과학)
Journal Title
Pharmacological Research
Issued Date
2007
Volume
56
Issue
3
Keyword
EpicatechinATP-sensitive potassium channelPhosphatidylinositol polyphosphateInsulin secretionCardiomyocyte
Abstract
Of green tea catechins, (−)-epigallocatechin-3-gallate (EGCG) and (−)-epicatechin-3-gallate (ECG), but not (−)-epicatechin and (−)-epigallocatechin, inhibit the activity of ATP-sensitive potassium (KATP) channels at tens of micromolar concentrations, ECG being three times more effective than EGCG. Further, we found that by using cloned beta cell-type KATP channels, only EGCG at 1 μM, a readily achievable plasma concentration by oral intake in humans, but not other epicatechins, significantly blocked channel reactivation after ATP wash-out, suggesting that interaction of phosphatidylinositol polyphosphates (PIP) with the channel was impaired by EGCG. In addition, a 10-fold higher concentration of EGCG reduced the channel sensitivity to ATP, but not AMP and ADP. This effect of EGCG was greater in the channel with the sulfonylurea receptor (SUR) than with the inwardly rectifying K+ channel (Kir6.2) alone. Neomycin, a polycation, profoundly suppressed the effect of EGCG. Expectedly, glucose-stimulated cytosolic Ca2+ elevation in rat pancreatic beta cells, and insulin secretory responses to high glucose loading in vivo were impaired by EGCG. In rabbit cardiac myocytes, dinitrophenol-induced opening of the channel was delayed by 1 μM EGCG. These results suggest that EGCG may interact with PIP-binding sites on the Kir6.2 subunit. SUR further endows EGCG with an ability to interfere with an interaction of the γ-phosphate tail of ATP with Kir6.2. The specificity of EGCG possibly implies that 5′-OH of the B-ring on the pyrogallol moiety in the EGCG molecule may be critical for these actions of EGCG on the KATP channel.

Keywords
Epicatechin;
ATP-sensitive potassium channel;
Phosphatidylinositol polyphosphate;
Insulin secretion;
Cardiomyocyte
Keimyung Author(s)(Kor)
배재훈
송대규
임정근
조호찬
Publisher
School of Medicine
Citation
Jun-Yup Jin et al. (2007). Uncoupling by (-)-epigallocatechine-3-gallate of ATP-sensitive potassium channels from phosphatidylinositol polyphosphates and ATP. Pharmacological Research, 56(3), 237–247. doi: 10.1016/j.phrs.2007.06.004
Type
Article
ISSN
1043-6618
Source
https://www.sciencedirect.com/science/article/pii/S1043661807001272?via%3Dihub
DOI
10.1016/j.phrs.2007.06.004
URI
https://kumel.medlib.dsmc.or.kr/handle/2015.oak/33666
Appears in Collections:
1. School of Medicine (의과대학) > Dept. of Internal Medicine (내과학)
1. School of Medicine (의과대학) > Dept. of Neurology (신경과학)
1. School of Medicine (의과대학) > Dept. of Physiology (생리학)
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