Regional differences in distribution and functional expression of small-conductance Ca2+-activated K+ channels in rat brain.
Small-conductance Ca2+-activated K+ (SK) channels are important for excitability control and afterhyperpolarizations in vertebrate neurons and have been implicated in regulation of the functional state of the forebrain. We have examined the distribution, functional expression, and subunit composition of SK channels in rat brain. Immunoprecipitation detected solely homotetrameric SK2 and SK3 channels in native tissue and their constitutive association with calmodulin. Immunohistochemistry revealed a restricted distribution of SK1 and SK2 protein with highest densities in subregions of the hippocampus and neocortex. In contrast, SK3 protein was distributed more diffusely in these brain regions and predominantly expressed in phylogenetically older brain regions. Whole-cell recording showed a sharp segregation of apamin-sensitive SK current within the hippocampal formation, in agreement with the SK2 distribution, suggesting that SK2 homotetramers underlie the apamin-sensitive medium afterhyperpolarizations in rat hippocampus.
Sailer
Claudia A
CA
Institute for Biochemical Pharmacology, University Innsbruck, A-6020 Innsbruck, Austria.
Hu
Hua
H
Kaufmann
Walter A
WA
Trieb
Maria
M
Schwarzer
Christoph
C
Storm
Johan F
JF
Knaus
Hans-Günther
HG
D000818:Animals; D000918:Antibody Specificity; D001030:Apamin / Q000493:pharmacokinetics; D001667:Binding, Competitive / Q000502:physiology; D001921:Brain / Q000166:cytology / Q000378:metabolism*; D001923:Brain Chemistry; D002147:Calmodulin / Q000378:metabolism; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism; D006624:Hippocampus / Q000737:chemistry / Q000166:cytology / Q000378:metabolism; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D019579:Neocortex / Q000737:chemistry / Q000166:cytology / Q000378:metabolism; D009865:Oocytes / Q000737:chemistry / Q000378:metabolism; D009928:Organ Specificity / Q000502:physiology; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000032:analysis / Q000378:metabolism*; D024681:Potassium Channels, Calcium-Activated; D011233:Precipitin Tests; D051381:Rats; D017207:Rats, Sprague-Dawley; D051640:Small-Conductance Calcium-Activated Potassium Channels; D014981:Xenopus
D002147:Calmodulin; C496896:Kcnn1 protein, rat; C496899:Kcnn2 protein, rat; C496901:Kcnn3 protein, rat; D015221:Potassium Channels; D024681:Potassium Channels, Calcium-Activated; D051640:Small-Conductance Calcium-Activated Potassium Channels; D001030:Apamin; D000242:Cyclic AMP