TASK-like conductances are present within hippocampal CA1 stratum oriens interneuron subpopulations.
TASK-1 (KCNK3) and TASK-3 (KCNK9) are members of the two-pore domain potassium channel family and form either homomeric or heteromeric open-rectifier (leak) channels. Recent evidence suggests that these channels contribute to the resting potential and input resistance in several neuron types, including hippocampal CA1 pyramidal cells. However, the evidence for TWIK-related acid-sensitive potassium (TASK)-like conductances in inhibitory interneurons is less clear, and mRNA expression has suggested that TASK channels are expressed in only a subpopulation of interneurons. Here we use immunocytochemistry to demonstrate prominent TASK-3 protein expression in both parvalbumin-positive- and a subpopulation of glutamic acid decarboxylase (GAD)67-positive interneurons. In addition, a TASK-like current (modulated by both pH and bupivacaine) was detected in 30-50% of CA1 stratum oriens interneurons of various morphological classes. In most neurons, basic shifts in pH had a larger effect on the TASK-like current than acidic, suggesting that the current is mediated by TASK-1/TASK-3 heterodimers. These data suggest that TASK-like conductances are more prevalent in inhibitory interneurons than previously supposed.
Torborg
Christine L
CL
Laboratory of Cellular and Synaptic Neurophysiology, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA. torborgc@mail.nih.gov
Berg
Allison P
AP
Jeffries
Brian W
BW
Bayliss
Douglas A
DA
McBain
Chris J
CJ
D000818:Animals; D002045:Bupivacaine / Q000494:pharmacology; D005968:Glutamate Decarboxylase / Q000378:metabolism; D006624:Hippocampus / Q000166:cytology / Q000502:physiology; D006863:Hydrogen-Ion Concentration; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D007395:Interneurons / Q000378:metabolism / Q000502:physiology*; D007527:Isoenzymes / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D009419:Nerve Tissue Proteins / Q000096:biosynthesis / Q000502:physiology*; D010320:Parvalbumins / Q000378:metabolism; D018408:Patch-Clamp Techniques; D024683:Potassium Channels, Tandem Pore Domain / Q000096:biosynthesis / Q000502:physiology*; D013004:Somatostatin / Q000378:metabolism
D007527:Isoenzymes; D009419:Nerve Tissue Proteins; D010320:Parvalbumins; D024683:Potassium Channels, Tandem Pore Domain; C420132:potassium channel subfamily K member 3; D013004:Somatostatin; D005968:Glutamate Decarboxylase; C402565:glutamate decarboxylase 1; D002045:Bupivacaine