Potentiation of muscarinic K+ channel activity by PD 81,723 in rat atrial myocytes

S. N. Wu, H. F. Lee, C. J. Tseng

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The 2-amino-3-benzoylthiophene derivative (PD 81,723), an allosteric enhancer of adenosine A1 receptors, was examined with the aid of patch-clamp recording. In cell-attached configuration, adenosine and acetylcholine activated the same population of K+ channels that had identical conductance (28 pS) and open time (1.5 msec), i.e., acetylcholine-activated K+ channels (KACh). The addition of PD 81,723 (30 μM) or dipyridamole (30 μM) to pipette solution alone did not significantly increase the activity of KACh channels. The opening probability of KACh activity was significantly increased when pipette solution contained adenosine (10 μM) plus PD 81,723 (10 μM) in comparison with that containing adenosine (10 μM) alone (0.43 vs. 0.24). The activity of KACh channels induced by acetylcholine between the absence and presence of PD 81,723 did not differ. The EC50 value for the effect of adenosine on KACh activity between the absence and presence of PD 81,723 was 6 μM vs. 2 μM. The single channel conductance and open time of KACh remained unchanged when both adenosine and PD 81,723 were included into the pipette. Thus, PD 81,723 can facilitate the opening of KACh channels by adenosine, not by acetylcholine. The kinetic activity of KACh channels per se was not altered by PD 81,723. And the opening activity of KACh channels was unaffected by endogenous adenosine plus PD 81,723.

Original languageEnglish
Pages (from-to)A713
JournalFASEB Journal
Issue number5
Publication statusPublished - 1998 Mar 20

All Science Journal Classification (ASJC) codes

  • Biotechnology
  • Biochemistry
  • Molecular Biology
  • Genetics


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