The inhibitory effect of propranolol on ATP-sensitive potassium channels in neonatal rat heart

Lai Hua Xie, Makoto Takano, Akinori Noma

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

1 Whole cell and single channel recordings of ATP-sensitive K. current (IK.ATP) were carried out in ventricular myocytes isolated from neonatal rat hearts. 2 (±)-Propranolol, a commonly used ß-blocker, inhibited the whole cell IK.ATP in a concentration-dependent manner with a half-maximal concentration (IC50) of 6.7 ± 1.4 μM, whereas it blocked the inward rectifier K† current (IK.1) only at much higher concentrations (IC50= 102.4 ± 20.2 μM). The inhibition was time- and voltage-independent. 3 In the outside-out patch configuration, ( ± )-propranolol inhibited IK.ATP (IC50= 9.8 ± 2.9 μM) by decreasing the open probability of the channel without inducing additional noise in the open-channel current or a decrease of single channel conductance. The single channel current of IK.1 was also blocked by ( ± )-propranolol in the same way as IK.ATP. 4 ( + )-Propranolol, an optic isomer having no ß-blocking effect, inhibited IK.ATP (IC50) = 5.8 ± 1.0 μM). whilst atenolol, a selective ß-blocker had no effect. Neither GDPßS (1 mM) nor GTPγS (200 μM) included in the pipette solution modulated the inhibitory effect of ( ± )-propranolol. 5 We concluded that the inhibitory effect of ( ± )-propranolol was not via the ß-adrenergic signal transduction pathway, but by direct inhibition of IK.AYP channels.

Original languageEnglish (US)
Pages (from-to)599-604
Number of pages6
JournalBritish Journal of Pharmacology
Volume123
Issue number4
DOIs
StatePublished - 1998
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Pharmacology

Keywords

  • ATP-sensitive K channel
  • Patch clamp
  • Propranolol
  • Rat heart
  • ß-blocker

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