Spontaneous electrical activity of interstitial cells of Cajal isolated from canine proximal colon.
Interstitial cells of Cajal (ICC) have been suggested as pacemaker cells in the gastrointestinal tract. A method was developed to isolate ICC from the slow-wave pacemaker region of the canine proximal colon. These cells were identified under phase-contrast microscopy, and their identity was verified by comparing their ultrastructure with the morphology of ICC in situ. Patch-clamp experiments demonstrated that these cells are excitable; voltage-dependent inward and outward currents were elicited by depolarization. Inward current transients were identified as calcium currents. A portion of the outward current appears to be due to Ca2+-activated K channels commonly expressed in these cells. ICC were also spontaneously active, generating electrical depolarizations similar in waveform to slow-wave events of intact colonic muscles. These findings are consistent with the hypothesis that ICC initiate rhythmicity in the colon.
Langton
P
P
Department of Physiology, University of Nevada School of Medicine, Reno 89511.
Ward
S M
SM
Carl
A
A
Norell
M A
MA
Sanders
K M
KM
D000818:Animals; D002118:Calcium / Q000494:pharmacology; D015220:Calcium Channels / Q000502:physiology; D003106:Colon / Q000166:cytology / Q000502:physiology* / Q000648:ultrastructure; D004285:Dogs; D004553:Electric Conductivity; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D008564:Membrane Potentials; D008854:Microscopy, Electron; D009130:Muscle, Smooth / Q000166:cytology / Q000502:physiology* / Q000648:ultrastructure; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology
D015220:Calcium Channels; D015221:Potassium Channels; D002118:Calcium