A Possibility That the ATP-Sensitive Potassium Channel in Coronary Artery Has a High-Affinity Internal Binding Site for Tetraalkylammonium

Kensuke Orito, Norio Taira, Teruyuki Yanagisawa

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)

Abstract

The functionally responsible sites for the blocking action of tetraalkylammonium ions (TAAs) in ATP-sensitive K+ (KATP) channels opened by levcromakalim were estimated in canine coronary artery. Tetraethylammonium (TEA) and tetrabutylammonium (TBA) inhibited the levcromakalim-induced relaxation in a noncompetitive manner. Analyses of the noncompetitive antagonism revealed that the binding constant of TBA was about 900 times lower than that of TEA, although the reported affinity of TBA for the internal binding site in various K'channels was only 10 times higher than that of TEA. TBA is much more lipid-soluble and permeable through membranes than TEA. Thus, TBA blocks KATP channels by binding to a possible high-affinity internal site for TAAs, whereas TEA seems to bind to the external site.

Original languageEnglish
Pages (from-to)297-301
Number of pages5
JournalJapanese Journal of Pharmacology
Volume64
Issue number4
DOIs
Publication statusPublished - 1994

Keywords

  • ATP-sensitive K+ (KATP) channel
  • Levcromakalim
  • Tetraalkylammonium ion

ASJC Scopus subject areas

  • Pharmacology

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