Chloride conductance contributes to period determination of a neuronal circadian pacemaker.
The isolated eye of Bulla gouldiana, a marine mollusc, is a circadian pacemaker. Previous studies have shown that membrane potential changes of neurons at the base of the Bulla retina play a critical role in the expression of the circadian rhythm and that the free-running period can be modified by chronic alteration of the resting membrane potential. We now report that treatments which inhibit CI- conductance shorten the free-running period. Substitution of CI- with the anions SO4(2-), isethionate and glutamate significantly shorten the period of the ocular rhythm in vitro. Furthermore, addition of the CI- channel blocker 9-anthracene-carboxylic acid (9-AC) is also effective at shortening the period of the circadian rhythm. These data suggest that a CI- conductance participates in determining the free-running period of the circadian pacemaker cells. This is the first report of CI- conductance involvement in a circadian system and the effect is remarkable in that few treatments are known which reliably shorten the period of circadian clocks.
Khalsa
S B
SB
Department of Biology, University of Virginia, Charlottesville 22901.
Ralph
M R
MR
Block
G D
GD
D000818:Animals; D000873:Anthracenes / Q000494:pharmacology; D018118:Chloride Channels; D002940:Circadian Rhythm; D005971:Glutamates / Q000494:pharmacology; D066298:In Vitro Techniques; D007473:Ion Channels / Q000187:drug effects / Q000502:physiology*; D007513:Isethionic Acid / Q000494:pharmacology; D008564:Membrane Potentials; D008565:Membrane Proteins / Q000502:physiology*; D008974:Mollusca; D009474:Neurons / Q000502:physiology*; D009799:Ocular Physiological Phenomena; D009900:Optic Nerve / Q000502:physiology; D013431:Sulfates / Q000494:pharmacology
D000873:Anthracenes; D018118:Chloride Channels; D005971:Glutamates; D007473:Ion Channels; D008565:Membrane Proteins; D013431:Sulfates; C010030:9-anthroic acid; D007513:Isethionic Acid