Regulation of ATP-sensitive K+ channels by ATP and nucleotide diphosphate in rabbit portal vein

M. Kamouchi, K. Kitamura

Research output: Contribution to journalArticle

46 Citations (Scopus)

Abstract

The modulation of ATP-sensitive K+ (K(ATP))-channel activity was investigated by recording single-channel currents in isolated smooth muscle cells from rabbit portal vein. K+-channel openers (KCOs; pinacidil, lemakalim, and nicorandil) induced burstlike openings of single K(ATP) channels in the cell-attached configuration. After patch excision, K(ATP) channels showed 'run-down' phenomenon in the presence of KCOs, but subsequent application of Mg-ATP (1 mM) restored K(ATP)-channel activity. Removal of Mg- ATP resulted in transient augmentation of K(ATP) currents, which eventually decayed out. Nucleotide diphosphates (NDPs; GDP, ADP, UDP, IDP, and CDP) also induced channel reopening in the presence of KCOs, which was markedly enhanced by addition of Mg2+ in millimolar concentrations at the internal side of the membrane. The dose-response relation between ATP and the UDP- induced K(ATP)-channel activity was shifted to the right in the presence of Mg2+ (2 mM). These results suggest that intracellular ATP, NDPs, and Mg2+ regulate the channel state of K(ATP) channels (operative and inoperative states) and that KCOs open K(ATP) channels only in the operative state.

Original languageEnglish
Pages (from-to)H1687-H1698
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume266
Issue number5 35-5
Publication statusPublished - Jun 13 1994

Fingerprint

Diphosphates
Portal Vein
Nucleotides
Adenosine Triphosphate
Rabbits
Uridine Diphosphate
Inosine Diphosphate
Pinacidil
Cytidine Diphosphate
Nicorandil
Cromakalim
Adenosine Diphosphate
Smooth Muscle Myocytes

All Science Journal Classification (ASJC) codes

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

Cite this

Regulation of ATP-sensitive K+ channels by ATP and nucleotide diphosphate in rabbit portal vein. / Kamouchi, M.; Kitamura, K.

In: American Journal of Physiology - Heart and Circulatory Physiology, Vol. 266, No. 5 35-5, 13.06.1994, p. H1687-H1698.

Research output: Contribution to journalArticle

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