Distribution Of Ca2+-Activated K+ Channel (SK2 and SK3) Immunoreactivity In Intestinal Smooth Muscles Of The Guinea-Pig

• Published in: Clinical and experimental pharmacology & physiology 2002-01, Vol.29 (1-2), p.18-25
• Main Authors: Klemm, Megan F, Lang, Richard J
• Format: Article
• Language: English
• Subjects: Animals; Ca2+-activated K+ channels; Colon - chemistry; Colon - ultrastructure; electron and confocal microscopy; Female; gastrointestinal tract; Guinea Pigs; Humans; interstitial cells of Cajal; intestinal inhibitory neurotransmission; Intestines - chemistry; Intestines - ultrastructure; Male; Muscle, Smooth - chemistry; Muscle, Smooth - ultrastructure; Neuropeptides - metabolism; Potassium Channels - metabolism; Potassium Channels - ultrastructure; Potassium Channels, Calcium-Activated - analysis; Potassium Channels, Calcium-Activated - ultrastructure; Rats; Small-Conductance Calcium-Activated Potassium Channels; Stomach - chemistry; Stomach - ultrastructure
• ISSN: 0305-1870; 1440-1681
• DOI: 10.1046/j.1440-1681.2002.03601.x

SUMMARY 1. The tissue distribution of small conductance Ca2+‐activated K+ channels (SK2 and SK3) was examined in three preparations of the guinea‐pig intestine: the taneia caeci and the circular muscle layer of the stomach and proximal colon. 2. The SK3 immunoreactive (SK3‐IR) cells were bi‐ or multipolar in appearance with numerous short processes, which formed an interconnecting network at the myenteric and submucous borders of the stomach and proximal colon. The SK3‐IR cells were also present within the circular muscle layer of these preparations and throughout the taenia caeci. 3. Although SK3‐IR cells had a similar distribution as cells immunoreactive for c‐Kit (c‐Kit‐IR), the marker for interstitial cells of Cajal (ICC), only 5–10% of c‐Kit‐IR ICC were also SK3‐IR. 4. The SK3‐IR cells were clearly ICC when examined with the electron microscope. Close associations of SK3‐IR ICC (ICC‐SK3) and nerves were often observed, as were gap junctions with SK3‐negative ICC and smooth muscle cells. 5. Punctate SK2 and SK3 channel immunoreactivity was present on the plasmalemmal surface of all smooth muscle cells examined. 6. We conclude that ICC‐SK3 are a subpopulation of ICC that are directly innervated by enteric inhibitory motor nerves.