title: Activity-independent homeostasis in rhythmically active neurons.
abstract: The shal gene encodes the transient potassium current (I(A)) in neurons of the lobster stomatogastric ganglion. Overexpression of Shal by RNA injection into neurons produces a large increase in I(A), but surprisingly little change in the neuron's firing properties. Accompanying the increase in I(A) is a dramatic and linearly correlated increase in the hyperpolarization-activated inward current (I(h)). The enhanced I(h) electrophysiologically compensates for the enhanced I(A), since pharmacological blockade of I(h) uncovers the physiological effects of the increased I(A). Expression of a nonfunctional mutant Shal also induces a large increase in I(h), demonstrating a novel activity-independent coupling between the Shal protein and I(h) enhancement. Since I(A) and I(h) influence neuronal activity in opposite directions, our results suggest a selective coregulation of these channels as a mechanism for constraining cell activity within appropriate physiological parameters.
authors.affiliation: Department of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853, USA. jm2107@columbia.edu
authors.forename: Jason N
authors.initials: JN
authors.lastname: MacLean
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhang
authors.forename: Bruce R
authors.initials: BR
authors.lastname: Johnson
authors.forename: Ronald M
authors.initials: RM
authors.lastname: Harris-Warrick
mesh_terms: D000200:Action Potentials / Q000235:genetics*; D000818:Animals; D001683:Biological Clocks / Q000235:genetics; D004558:Electric Stimulation; D005260:Female; D017952:Ganglia, Invertebrate / Q000166:cytology / Q000502:physiology*; D006706:Homeostasis / Q000235:genetics; D009154:Mutation / Q000502:physiology; D009415:Nerve Net / Q000502:physiology*; D009474:Neurons / Q000502:physiology*; D009865:Oocytes; D009924:Organ Culture Techniques; D033521:Palinuridae / Q000166:cytology / Q000502:physiology*; D010507:Periodicity; D015221:Potassium Channels / Q000235:genetics / Q000378:metabolism*; D024642:Potassium Channels, Voltage-Gated; D012313:RNA / Q000494:pharmacology; D051637:Shaker Superfamily of Potassium Channels; D051672:Shal Potassium Channels; D009435:Synaptic Transmission / Q000235:genetics; D014982:Xenopus laevis
chemical_list: D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D051637:Shaker Superfamily of Potassium Channels; D051672:Shal Potassium Channels; D012313:RNA