The Korean Journal of Physiology and Pharmacology

The Korean Society of Pharmacology (대한약리학회)
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Modulation of Inwardly Rectifying $K^+$ Channel by Intracellular and Extracellular pH in Bovine Aortic Endothelial Cells

  • Park, Kyu-Sang (Department of Physiology, Wonju College of Medicine, Yonsei University) ;
  • Kong, In-Deok (Department of Physiology, Wonju College of Medicine, Yonsei University) ;
  • Lee, Joong-Woo (Department of Physiology, Wonju College of Medicine, Yonsei University) ;
  • Rhim, Hye-Whon (Biomedical Research Center, KIST) ;
  • Kim, Young-Chul (Department of Physiology, College of Medicine, Chosun University) ;
  • So, In-Suk (Department of Physiology and Biophysics, Seoul National University College of Medicine) ;
  • Kim, Ki-Whan (Biomedical Research Center, KIST,Department of Physiology and Biophysics, Seoul National University College of Medicine)
  • Published : 2002.10.21
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Abstract

The effects of intracellular and extracellular pH on the inwardly rectifying $K^+$ (IRK) channel of the bovine aortic endothelial cells (BAECs) were examined using whole-cell patch-clamp technique. The IRK current, efficiently blocked by $Ba^{2+}\;(200{\mu}M),$ is the most prominent membrane current in BAECs, which mainly determines the resting membrane potential. The expression of Kir2.1 was observed in BAECs using reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. Intracellular alkalinization, elicited by the extracellular substitution of NaCl with $NH_4Cl$ (30 mM), significantly augmented the amplitude of IRK current. On the contrary, the amplitude of IRK current was attenuated by the Na-acetate (30 mM)-induced intracellular acidification. The changes in extracellular pH also closely modulated the amplitude of IRK current, which was decreased to $40.2{\pm}1.3%$ of control upon switching the extracellular pH to 4.0 from 7.4. The extracellular pH value for half-maximal inhibition (pK) of IRK current was 5.11. These results demonstrate that the activity of IRK channel in BAECs, probably Kir2.1, was suppressed by proton at both sides of plasma membrane.

Keywords

References

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