title: Distribution of Ca2+-activated K+ channel (SK2 and SK3) immunoreactivity in intestinal smooth muscles of the guinea-pig.
abstract: 1. The tissue distribution of small conductance Ca(2+)-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.
authors.affiliation: Department of Physiology, Monash University, Clayton, Victoria, Australia.
authors.forename: Megan F
authors.initials: MF
authors.lastname: Klemm
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Lang
mesh_terms: D000818:Animals; D003106:Colon / Q000737:chemistry / Q000648:ultrastructure; D005260:Female; D006168:Guinea Pigs; D006801:Humans; D007422:Intestines / Q000737:chemistry* / Q000648:ultrastructure; D008297:Male; D009130:Muscle, Smooth / Q000737:chemistry* / Q000648:ultrastructure; D009479:Neuropeptides / Q000378:metabolism*; D015221:Potassium Channels / Q000378:metabolism* / Q000648:ultrastructure; D024681:Potassium Channels, Calcium-Activated / Q000032:analysis / Q000648:ultrastructure; D051381:Rats; D051640:Small-Conductance Calcium-Activated Potassium Channels; D013270:Stomach / Q000737:chemistry / Q000648:ultrastructure
chemical_list: C406328:KCNN3 protein, human; C496899:Kcnn2 protein, rat; C496901:Kcnn3 protein, rat; D009479:Neuropeptides; D015221:Potassium Channels; D024681:Potassium Channels, Calcium-Activated; D051640:Small-Conductance Calcium-Activated Potassium Channels