Adrenergic modulation of potassium currents in isolated human atrial myocytes |
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Authors: | Ming-Jai Su Jo-Feng Chi Shu-Hsun Chu |
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Affiliation: | (1) Department of Surgery, College of Medicine, National Taiwan University, Taipei, Taiwan, ROC;(2) Pharmacological Institute College of Medicine, National Taiwan University, No. 1, Jen-Ai Rd., Sect. 1, 10018 Taipei, Taiwan (ROC) |
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Abstract: | The adrenergic modulation of inwardly rectifying and depolarization-activated outward potassium currents was studied in single cardiac myocytes obtained from the human atrium. Membrane currents were recorded in enzymatically dissociated cells using the whole-cell voltage-clamp technique. It was observed that, in the presence or absence of atenolol (or 1 µM propranolol), 30 µM phenylephrine attenuated inwardly rectifying and depolarization-activated outward potassium currents including both transient and late-activated current. This suppressant effect of phenylephrine could be prevented by pretreatment with an -adrenoceptor antagonist. Isoproterenol (30 µM) increased the late outward potassium current and net transient outward current. It is concluded that, in human atrial myocytes, -adrenergic activation reduces depolarization-activated transient and late outward potassium current and inwardly rectifying background potassium current. -Adrenergic activation resulted in an increase in the depolarization-activated transient and late outward potassium current. |
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Keywords: | Human atrial myocytes Potassium currents Adrenergic modulation Phenylephrine Isoproterenol |
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