title: Calcium Release from Stores Inhibits GIRK.
abstract: Synaptic transmission is mediated by ionotropic and metabotropic receptors that together regulate the rate and pattern of action potential firing. Metabotropic receptors can activate ion channels and modulate other receptors and channels. The present paper examines the interaction between group 1 mGluR-mediated calcium release from stores and GABAB/D2-mediated GIRK currents in rat dopamine neurons of the Substantia Nigra. Transient activation of mGluRs decreased the GIRK current evoked by GABABand D2 receptors, although less efficaciously for D2. The mGluR-induced inhibition of GIRK current peaked in 1 s and recovered to baseline after 5 s. The inhibition was dependent on release of calcium from stores, was larger for transient than for tonic currents, and was unaffected by inhibitors of PLC, PKC, PLA2, or calmodulin. This inhibition of GABABIPSCs through release of calcium from stores is a postsynaptic mechanism that may broadly reduce GIRK-dependent inhibition of many central neurons.
authors.affiliation: Vollum Institute, Oregon Health and Science University, Portland, OR 97239, USA.
authors.forename: Paul F
authors.initials: PF
authors.lastname: Kramer
authors.affiliation: Vollum Institute, Oregon Health and Science University, Portland, OR 97239, USA. Electronic address: williamj@ohsu.edu.
authors.forename: John T
authors.initials: JT
authors.lastname: Williams
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002147:Calmodulin / Q000378:metabolism; D004298:Dopamine / Q000378:metabolism; D059290:Dopaminergic Neurons / Q000378:metabolism*; D051676:G Protein-Coupled Inwardly-Rectifying Potassium Channels / Q000235:genetics / Q000378:metabolism*; D011493:Protein Kinase C / Q000378:metabolism; D051381:Rats; D017448:Receptors, Dopamine D2 / Q000378:metabolism*; D018080:Receptors, GABA-B / Q000378:metabolism*; D018094:Receptors, Metabotropic Glutamate / Q000378:metabolism*; D013378:Substantia Nigra / Q000378:metabolism / Q000502:physiology; D009435:Synaptic Transmission / Q000235:genetics / Q000502:physiology; D010738:Type C Phospholipases / Q000378:metabolism
chemical_list: D002147:Calmodulin; D051676:G Protein-Coupled Inwardly-Rectifying Potassium Channels; D017448:Receptors, Dopamine D2; D018080:Receptors, GABA-B; D018094:Receptors, Metabotropic Glutamate; C104077:metabotropic glutamate receptor type 1; D011493:Protein Kinase C; D010738:Type C Phospholipases; D002118:Calcium; D004298:Dopamine
keywords: D2; GABA(B); GIRK inhibition; IP(3); calcium; dopamine neurons; group I mGluR