Korean J Physiol Pharmacol.  2002 Feb;6(1):47-56.

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

• Jun JY
• Yeum CH
• Yoon PJ
• Jang IY
• Cho NS
• Cho SH
• Kong ID
• Kim TW
• So I
• Kim KW

Abstract

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 Ba2+ and Cs+, but not by glibenclamide. With 90 mM K+ in bath, the Ba2+- 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.

Keyword

Inwardly rectifying K+ channels; Ba2+-sensitive currents; Gastric myocytes

MeSH Terms

Baths
Glyburide
Membranes
Muscle Cells*
Muscle, Smooth
Tea
Glyburide
Tea