Inwardly Rectifying $K^+$ Currents in Gastric Myocytes of Guinea-pig

  • Jun, Jae-Yeoul (Department of Physiology, College of Medicine, Chosun University) ;
  • Yeum, Cheol-Ho (Department of Physiology, College of Medicine, Chosun University) ;
  • Yoon, Pyung-Jin (Department of Physiology, College of Medicine, Chosun University) ;
  • Jang, In-Youb (Department of Anatomy, College of Medicine, Chosun University) ;
  • Cho, Nam-Soo (Department of Emergency Medicine, College of Medicine, Chosun University) ;
  • Cho, Soo-Hyeong (Department of Emergency Medicine, College of Medicine, Chosun University) ;
  • Kong, In-Deok (Department of Physiology, Wonju Medical School, Yonsei University) ;
  • Kim, Tae-Wan (Department of Physiology and Cell Biology, College of Medicine, Seoul Notional University) ;
  • So, In-Suk (Department of Physiology and Cell Biology, College of Medicine, Seoul Notional University) ;
  • Kim, Ki-Whan (Department of Physiology and Cell Biology, College of Medicine, Seoul Notional University)
  • Published : 2002.02.21


To identify the presence of inwardly rectifying $K^+$ channels and its characteristics, membrane currents were measured using a whole-cell patch clamp from isolated gastric myocytes of guinea-pig. Change of external $K^+$ concentration from 5 to 90 mM induced an inward current at a holding potential of -80 mV. The high $K^+-induced$ inward current was blocked by $Ba^{2+}$ and $Cs^+,$ but not by glibenclamide. With 90 mM $K^+$ in bath, the $Ba^{2+}-$ and $Cs^+-sensitive$ currents showed strong inward rectification. Ten mM TEA weakly blocked the inward current only at potentials more negative than -50 mV. With 90 mM $K^+$ in bath, hyperpolarizing step pulses from -10 mV induced inward currents, which were inactivated at potentials more negative than -70 mV. Reduction of external $K^+$ to 60 mM decreased the amplitudes of the currents and shifted the reversal potential to more negative potential. The inactivation of inward $K^+$ current at negative clamp voltage was not affected by removing external $Na^+.$ These results suggest that the inwardly rectifying $K^+$ channels may exist in gastric smooth muscle.


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