Spontaneous electrical activity of interstitial cells of Cajal isolated from canine proximal colon.

TLDR

Interstitial cells of Cajal are proposed pacemaker cells in the gastrointestinal tract. The authors isolated ICC from the slow‑wave pacemaker region of the canine proximal colon, identified them by phase‑contrast microscopy, and confirmed their identity through ultrastructural comparison with in situ ICC. Patch‑clamp recordings revealed that ICC are excitable, exhibiting voltage‑dependent calcium inward currents and Ca²⁺‑activated K⁺ outward currents, and they spontaneously generate depolarizations resembling colonic slow waves, supporting their role in initiating colonic rhythmicity.

Abstract

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.