Ca2+-activated K+ current in freshly isolated c-Kit positive cells in guinea-pig stomach.
This study was designed to isolate Ca2+-activated K+ current (I(KCa)) and elucidate its physiological significance in freshly isolated interstitial cells of Cajal (ICCs) of guinea-pig stomach. Single ICC was freshly isolated by enzymatically dissociating from myenteric border of gastric antrum free of circular muscles, and conventional whole-cell voltage clamp technique including immunohistochemical techniques were employed to characterize the cells: In myenteric border of gastric antrum, ICC-MY (ICCs from myenteric border) were detected by immunohistochemical reactivity, and single ICC-MY which has many branches was immunohistochemically c-Kit positive. Under K+-rich and 0.1 mM ethylene glycol-bis (2-aminoethyl ether)-N,N,N',N'-tetraacetic acid pipette solution, ICC produced spontaneous inward current (-256 +/- 92.2 pA). When step-depolarizing pulse from -80 to +80 mV was applied at holding potential (V(h)) of -80 mV, voltage-dependent outward currents were recorded with superimposed spontaneous transient outward currents (STOCs). Both STOCs and outward currents were reversibly affected by tetraethylammonium chloride (TEA) and iberiotoxin (IbTX); 2 mM TEA and 200 nM IbTX completely abolished STOCs and significantly inhibited outward K+ current over the whole potential range tested for current/voltage (I/V) relationship. In addition, TEA delayed repolarization phase of spontaneous inward current. The present results indicate the presence of I(KCa) in a single ICC, and it might be involved in regulation of repolarizing phase of spontaneous inward current in guinea-pig stomach.
Kim
Young Chul
YC
Department of Physiology, Chungbuk National University, College of Medicine, Cheongju, Korea. physiokyc@chungbuk.ac.kr
Suzuki
Hikaru
H
Xu
Wen-Xie
WX
Choi
Woong
W
Kim
Seok-Hyung
SH
Lee
Sang Jin
SJ
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D006168:Guinea Pigs; D008564:Membrane Potentials / Q000187:drug effects; D018408:Patch-Clamp Techniques; D010455:Peptides / Q000494:pharmacology; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology*; D019009:Proto-Oncogene Proteins c-kit / Q000378:metabolism*; D011706:Pyloric Antrum / Q000166:cytology / Q000502:physiology*; D019789:Tetraethylammonium / Q000494:pharmacology
D010455:Peptides; D015221:Potassium Channels; D019789:Tetraethylammonium; C064719:iberiotoxin; D019009:Proto-Oncogene Proteins c-kit; D002118:Calcium