Characterization of ion channels in human coronary artery endothelial cells

Authors

  • Katesirin Ruamyod
  • Wattana B. Watanapa
  • Chairat Shayakul

Abstract

Endothelial ion channels play important roles in regulating coronary vascular tone by modulating endothelial intracellular Ca2+ concentration, which in turn controls the production and release of vasoactive substances. These transport molecules either provide direct Ca2+ influx pathway through Ca2+-permeable non-selective cation channels, or influence Ca2+ electrochemical driving force via alterations in the K+ and Cl conductance. We aimed to characterize the type and contribution of ionic currents in human coronary artery endothelial cells (HCAECs), using whole-cell patch clamp technique. Average peak whole-cell current amplitude of HCAECs at +60 mV was 8.07 ± 0.31 pA/pF (n = 336). The percentages of total currents blocked in 10 μM La3+, 250 μM DIDS, 1 nM apamin, and 10 μM clotrimazole, were 36.11 ± 1.42% (n = 8), 20.34 ± 2.81% (n = 8), 15.51 ± 1.92% (n = 6), and 19.82 ± 2.02% (n = 10) at +60 mV, suggesting the fractions contributed by non-selective cation, Cl, small-conductance Ca2+-sensitive K+ (SKCa), and intermediate-conductance Ca2+-sensitive K+ (IKCa) channels, respectively (P < 0.05). In addition, 1 mM TEA and 100 nM iberiotoxin could suppress 16.51 ± 5.35% (n = 6) and 16.02 ± 3.99% (n = 5) of the control currents at +60 mV, indicating that the fraction responsible by large-conductance Ca2+-sensitive K+ (BKCa) channel was about 16%. Thus, HCAEC currents at +60 mV were mostly (> 50%) made up of K+ currents, which included, at least, BKCa, IKCa, and SKCa currents. The rest of the currents passed through NSC and Cl channels. Finally, 100 μM Ba2+, a specific blocker of inward rectifier potassium (Kir) channel, inhibited 37.06 ± 4.59% (n = 6) at -100 mV. These observations could be a basis for further investigation on the role of endothelial ion channels in coronary vascular physiology in human.

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Author Biographies

Katesirin Ruamyod

Department of Physiology, Faculty of Medicine Siriraj Hospital, Bangkok 10700, Thailand.

Wattana B. Watanapa

Department of Physiology, Faculty of Medicine Siriraj Hospital, Bangkok 10700, Thailand.

Chairat Shayakul

Department of Medicine, Faculty of Medicine Siriraj Hospital, Bangkok 10700, Thailand.

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Published

2015-05-28

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Section

Original Articles