Amino Acids

, Volume 9, Issue 3, pp 235–246 | Cite as

A dual action of taurine on the delayed rectifier K+ current in embryonic chick cardiomyocytes

  • H. Satoh


Effects of taurine on the delayed rectifier K+ channel in isolated 10-day-old embryonic chick ventricular cardiomyocytes were examined at different intracellular Ca2+ concentrations ([Ca]i), using whole-cell voltage and current clamp techniques. Experiments were performed at room temperature (22°C). Test pulses were applied between -20 to +90m V from a holding potential of -40mV. When [Ca]i was pCa 7, addition of 10 and 20 mM taurine to the bath solution reduced the delayed rectifier K+ current (IK) at +90mV by 17.4 ± 2.8% (n = 5, P < 0.01) and 25.5 ± 2.6% (n = 5, P < 0.001), respectively. In contrast, when [Ca]i was pCa 10, IK at +90 mV was enhanced by 19.1 ± 3.1% (n = 7, P < 0.01) at 10mM taurine, and by 29.3 ± 2.4% (n = 7, P < 0.001) at 20mM taurine. The voltage of half-maximum activation (V1/2) was shifted in a hyperpolarizing direction; at pCa 7, the value was +0.2 ± 2.2mV (n = 5) in control and -10.6 ± 1.8mV (n = 5) in 20mM taurine. At pCa 10, the V1/2 value was +18.5 ± 4.6mV (n = 5) in control and +6.6 ± 5.2mV (n = 5) in taurine (20mM). Taurine decreased the action potential duration (APD) at pCa 10, but at pCa 7 did not affect it. In addition, taurine enhanced the transient outward current in a concentration-dependent manner. These results indicate that taurine modulates the delayed rectifier K+ channel, an effect dependent on [Ca]i and capable of regulating APD.


Amino acids Taurine Delayed rectifier K+ channel Action potential duration Transient outward current Embryonic chick heart cells Whole-cell voltage and current clamps 


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Copyright information

© Springer-Verlag 1995

Authors and Affiliations

  • H. Satoh
    • 1
  1. 1.Department of PharmacologyNara Medical UniversityKashihara, NaraJapan

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