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A Novel Pacemaker Mechanism Drives Gastrointestinal Rhythmicity
Kenton M. Sanders1, Tamás Ördög, Sang Don Koh
1Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV 89557.
Summary
Interstitial cells of Cajal (ICC) generate electric rhythmicity in the gut. Calcium release from the endoplasmic reticulum and uptake by mitochondria initiates these pacemaker currents, driving muscle contractions.
Area of Science:
- Gastroenterology
- Cell Physiology
- Muscle Biology
Background:
- The gastrointestinal tract relies on electric pacemaker activity for motility.
- Interstitial cells of Cajal (ICC) are the primary source of this spontaneous electrical activity.
- Previous understanding of ICC pacemaker mechanisms was incomplete.
Purpose of the Study:
- To elucidate the novel mechanism underlying electric rhythmicity in gastrointestinal muscles.
- To investigate the role of intracellular calcium dynamics in ICC pacemaker currents.
Main Methods:
- Culturing of interstitial cells of Cajal (ICC).
- Electrophysiological recordings to analyze inward currents.
- Investigating the influence of calcium release and uptake on pacemaker activity.
Main Results:
- ICC exhibit rhythmic electrical activity in culture.
- ICC generate voltage-independent inward currents through a nonselective cation conductance.
- Pacemaker currents are initiated by Ca(2+) release from the endoplasmic reticulum and subsequent uptake by mitochondria.
Conclusions:
- A novel mechanism involving intracellular calcium handling initiates gastrointestinal pacemaker currents.
- This calcium-dependent process provides the basis for electric rhythmicity in gastrointestinal muscles.
- Findings offer new insights into the regulation of gut motility.