[Characterization of pacemaking currents in cultured interstitial cells of Cajal from mice small intestine].
OBJECTIVE
Gastrointestinal motility is initiated by the periodic generation of slow waves. Interstitial cells of Cajal (ICC) are pacemaker cells that generate slow waves and drive spontaneous mechanical contractions of the gastrointestinal smooth muscle. Slow waves generate the periodic activation of spontaneous inward currents (pacemaker currents). The aim of this study was to investigate the characterization of pacemaker currents of ICC.


METHODS
The ICC in mice small intestine were cultured with stem cell factor for 2 days, and then we recorded pacemaker currents and slow waves using a whole-cell patch clamp technique.


RESULTS
Under voltage clamp at -80 mV of holding potential, ICC generated pacemaker currents. Tetrodotoxin and nifedipine did not affect on the pacemaker currents. In addition, tetraethylammonium, 4-aminopyridine and glibenclamide did not affect on the pacemaker currents. The reduction of external Na+ concentrations inhibited pacemaker currents. Moreover, these currents were completely abolished in the external Ca2+-free condition. Gadolinium and flufenamic acid, inhibitors of non-selective cationic currents, inhibited pacemaker currents. Thapsigargin and cyclopiazoic acid, inhibitors of Ca2+-ATPase in endoplasmic reticulum, abolished pacemaker currents. Carbachol depolarized membrane potential and increased inward currents.


CONCLUSIONS
These results suggest that pacemaker currents are mediated by the activation of non-selective cation channel and become a target of neurotransmitters in regulation of intestinal motility.
Chang
Sung Jong
SJ
Department of Internal Medicine, Chosun University College of Medicine, Dong-gu, GwangJu, Korea.
Cho
Eun Tak
ET
Heo
Gwang Sik
GS
Park
Chan Guk
CG
Kim
Man Woo
MW
Chang
In Youb
IY
Shin
Moo Kyoung
MK
Cha
Kyung Hun
KH
Yeum
Cheol Ho
CH
Jun
Jae Yeoul
JY
D000818:Animals; D002478:Cells, Cultured; D004594:Electrophysiology; D005769:Gastrointestinal Motility / Q000502:physiology*; D007421:Intestine, Small / Q000166:cytology*; D007473:Ion Channels / Q000187:drug effects; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D008807:Mice, Inbred BALB C; D009130:Muscle, Smooth / Q000166:cytology / Q000502:physiology; D018408:Patch-Clamp Techniques
D007473:Ion Channels