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Potassium currents in rat colonic smooth muscle cells and changes during development and aging
Z Xiong1, N Sperelakis, A Noffsinger
1Department of Molecular and Cellular Physiology, University of Cincinnati College of Medicine, OH 45267-0576, USA.
Pflugers Archiv : European Journal of Physiology
|August 1, 1995
Summary
Voltage-gated potassium channel currents (IK) in rat colonic myocytes were studied. The study identified calcium-sensitive and calcium-insensitive IK currents, with the latter decreasing significantly in neonatal rats.
Area of Science:
- Physiology
- Electrophysiology
- Gastroenterology
Background:
- Previous research indicated developmental changes in L-type Ca2+ current density in rat colonic smooth muscle cells.
- Potassium (K+) currents are crucial for regulating cell excitability and colon motility.
Purpose of the Study:
- To investigate voltage-gated K+ channel currents (IK) in rat colonic myocytes across different ages.
- To characterize the different types of IK currents and their developmental changes.
Main Methods:
- Whole-cell voltage-clamp technique was employed on colonic myocytes from rats of various ages.
- Identification and characterization of calcium-sensitive [IK(Ca)] and calcium-insensitive IK currents.
- Pharmacological agents like tetraethylammonium ion (TEA+) and 4-aminopyridine (4-AP) were used.
Main Results:
- A Ca(2+)-sensitive K+ current [IK(Ca)] and two distinct Ca(2+)-insensitive outward K+ currents were identified.
- The Ca(2+)-insensitive IK component showed a significant decrease from 3-day-old to 40-day-old rats.
- No further decline in Ca(2+)-insensitive IK density was observed in aged rats (up to 480 days).
Conclusions:
- Developmental changes in K+ channel currents occur in rat colonic myocytes.
- The significant reduction in Ca(2+)-insensitive IK during the neonatal period may impact colon motility regulation.