Inwardly Rectifying K<SUP>⁢</SUP> Currents in Gastric Myocytes of Guinea-pig
Inwardly Rectifying K<SUP>⁢</SUP> Currents in Gastric Myocytes of Guinea-pig
- 대한생리학회-대한약리학회
- The Korean Journal of Physiology & Pharmacology
- 제6권 제1호
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2002.0147 - 56 (10 pages)
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<P> To identify the presence of inwardly rectifying K<SUP>⁢</SUP> 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<SUP>⁢</SUP> concentration from 5 to 90 mM induced an inward current at a holding potential of ⁣80 mV. The high K<SUP>⁢</SUP>-induced inward current was blocked by Ba<SUP>2⁢</SUP> and Cs<SUP>⁢</SUP>, but not by glibenclamide. With 90 mM K<SUP>⁢</SUP> in bath, the Ba<SUP>2⁢</SUP>- and Cs<SUP>⁢</SUP>-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<SUP>⁢</SUP> 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<SUP>⁢</SUP> to 60 mM decreased the amplitudes of the currents and shifted the reversal potential to more negative potential. The inactivation of inward K<SUP>⁢</SUP> current at negative clamp voltage was not affected by removing external Na<SUP>⁢</SUP>. These results suggest that the inwardly rectifying K<SUP>⁢ </SUP>channels may exist in gastric smooth muscle.
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