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The Na+/Ca2+ exchanger inhibitor KB-R7943 activates large-conductance Ca2+-activated K+ channels in endothelial and vascular smooth muscle cells
- The Na+/Ca2+ exchanger inhibitor KB-R7943 activates large-conductance Ca2+-activated K+ channels in endothelial and vascular smooth muscle cells
- Liang G.H.; Kim J.A.; Seol G.H.; Choi S.; Suh S.H.
- Ewha Authors
- 서석효; 최신규
- SCOPUS Author ID
- 서석효; 최신규
- Issue Date
- Journal Title
- European Journal of Pharmacology
- vol. 582, no. 41277, pp. 35 - 41
- SCI; SCIE; SCOPUS
- The effect of the selective inhibitor of Na+/Ca2+ exchanger (NCX), KB-R7943, on large-conductance Ca2+-activated K+ (BKCa) channels was examined in cultured human umbilical vein endothelial cells (HUVECs) and freshly isolated mouse aortic smooth muscle cells (MASMCs). In voltage-clamped cells, KB-R7943 reversibly activated BKCa currents in HUVECs and MASMCs. The EC50 of KB-R7943 for BKCa current activation in HUVECs was determined to be 6.78 ± 0.7 μM. In inside-out and outside-out patches, KB-R7943 markedly increased BKCa channel activity and slightly decreased single channel current amplitudes. In inside-out patches, KB-R7943 shifted the relationship between [Ca2+]i and open probability (Po) to the left; the [Ca2+]i required to evoke half-maximal activation changed from 1220 ± 68 nM (in the absence of KB-R7943) to 620 ± 199 nM (in the presence of 10 μM KB-R7943). In addition, KB-R7943 shifted the relationship between membrane potential and Po to the left; the membrane potential to evoke half-maximal activation changed from 76.86 ± 1.09 mV (in the absence of KB-R7943) to 49.62 ± 2.55 mV (in the presence of 10 μM KB-R7943). In conclusion, KB-R7943 was found to act as a potent BKCa channel activator, which increases the sensitivity of BKCa channels to cytosolic free Ca2+ and membrane potential, and thereby BKCa channel activity. These results should be considered when KB-R7943 is used as NCX blocker. © 2008 Elsevier B.V. All rights reserved.
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