• Title/Summary/Keyword: $K_{APT}$ channels

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Neonatal Diabetes Mellitus: A Focused Review on Beta Cell Function Abnormalities

  • Jung-Eun Moon
    • Journal of Interdisciplinary Genomics
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    • v.6 no.2
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    • pp.37-41
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    • 2024
  • Neonatal diabetes mellitus, or congenital diabetes mellitus, is a rare genetic disorder caused by abnormal β cell function and other causes. The symptoms of hyperglycemia that occur in neonatal diabetes. The symptoms of hyperglycemia that occur in neonatal diabetes may be transient or persistent. The most frequent genetic cause of neonatal diabetes characterized by abnormal β cell function is abnormalities at the 6q24 locus. Another possible cause is mutations in the ABCC8 or KCNJ11 genes, which code for potassium channels in pancreatic β cells. This underscores the importance of rapid genetic diagnosis following neonatal diabetes diagnosis and highlights the critical timing of sulfonylurea use.

Effects of potassium channel modulators on the fatigue velocity of mouse skeletal muscle (K+ 통로 조절 약물이 마우스 골격근의 피로현상에 미치는 영향)

  • Lee, Ki-ho;Ryu, Pan-dong;Lee, Mun-han;Lee, Hang
    • Korean Journal of Veterinary Research
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    • v.35 no.2
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    • pp.245-254
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    • 1995
  • The density of ATP-sensitive potassium($K_{APT}$) channels, that open as intracellular ATP concentration falls below a critical level, is very high in skeletal muscle surface membrane and those high density may imply that $K_{ATP}$ channels have very important physiological roles. To elucidate a role of $K_{ATP}$ in relation to fatigue, the modulating effects of potassium channel openers and blockers on the fatigue velocity(FV) of mouse extensor hallucis longus muscle(EHL) were investigated in vitro. Twitch contraction was induced by an electrical field stimulation (EFS: 24-48V, 20ms, 0.2-4Hz) and resulting contraction force was isometrically recorded. The twitch forces were gradually decreased to 25% of initial contraction force(ICF) in $37.52{\pm}1.55sec$($mean{\pm}s.e.m.$, n=135), indicating the fatigue phenomena. The mean velocity for development of the fatigue was measured during the period that twitch force decreased to half($FV_{0/0.5}$) and during the period from half to 25%($FV_{0.5/0.25}$) of ICF. The fatigue was induced once every one hour and the tissue response was stable for up to 4 hours. In control condition, ICF was $5.8{\pm}0.12g$ (n=144) and decreased to 50% of ICF with the mean fatigue velocity of $0.182{\pm}0.006g/sec$($FV_{0/0.5}$, n=135) and from 50% to 25% of ICF with $0.084{\pm}0.004g/sec$($FV_{0.5/0.25}$, n=135). Cromakalim($50{\mu}M$) significantly increased $FV_{0.5/0.25}$(n=4). Glibenclamide($IC_{50}>50{\mu}M$), $Ba^{2+}$($IC_{50}=10{\mu}M$), 4-aminopyridine($FV_{0/0.5}$, $IC_{50}=0.5mM$; $FV_{0.5/0.25}$, $IC_{50}=2mM$) decreased both $FV_{0/0.5}$ and $FV_{0.5/0.25}$ concentration-dependently up to 75%. $TEA^+$(30mM), E-4031($10{\mu}M$), tolbutamide(1mM) decreased $FV_{0.5/0.25}$, but apamin(300nM) and $TEA^+$(10mM) showed no significant effects. Our results suggest that activation of the $K_{ATP}$ channels may be major cause of $K^+$ outflux during development of the fatigue and the isolated EHL muscle could be an useful experimental preparation in studying the fatigue phenomena in skeletal muscle. In addition, the possibility of activation of delayed rectifier during the fatigue development remains to be studied further.

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Factors Influencing Buyers' Choice of Online vs. Offline Channel at Information Search and Purchase Stages (정보탐색과 구매 단계에서 온라인과 오프라인 채널선택의 영향요인)

  • Kim, Sang-Hoon;Park, Gye-Young;Park, Hyun-Jung
    • Journal of Distribution Research
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    • v.12 no.3
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    • pp.69-90
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    • 2007
  • This study is set out to investigate the factors that influence customers' behavior of choice and switching between online and offline channels, separating the purchase decision into two stages, i.e., information search and purchase. Factors influencing channel choice are found to differ from stage to stage. The main results of this study are as follows. At the information search stage, customers' channel knowledge had impacts on the choice of the channel. Customers are more likely to visit offline bookstores when they have hedonic shopping orientation and higher involvement level with books. On the contrary, customers are more apt to search online when they have a lot of online shopping experiences. At the purchase stage, the results varied according to the search channel. When customers search for information online, the following variables lead to online purchases: online shopping experiences with books, price-focused shopping orientation, and time availability for shopping. Perceived risk made customers purchase offline even though they searched online. In case of offline searching, customers with more convenience-focused, hedonic-focused shopping orientation and less tim availability purchased offline.

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