title: Circadian rhythm in intracellular Cl(-) activity of acutely dissociated neurons of suprachiasmatic nucleus.
abstract: A link between the circadian rhythm and the function of Cl(-)-permeable gamma-aminobutyric acid (GABA) type A (GABA(A)) receptors on suprachiasmatic nucleus (SCN) neurons was studied by measuring intracellular activity of Cl(-) (aCl) at different times during a circadian cycle in SCN neurons acutely dissociated from rat brains. To measure aCl, the voltage-clamp mode of the gramicidin-perforated patch-clamp technique was used, and reversal potential of GABA-induced currents (E(GABA)) was converted to aCl. Measured aCl was significantly higher at around noon (20.1 +/- 1.4 mM) than at three other time zones of a circadian cycle (means ranging from 11.6 to 14.3 mM). Chord conductance of GABA-induced currents showed no circadian changes, indicating a lack of circadian changes in the number or single-channel conductance of GABA(A) receptors. These results suggest that aCl participates in modulating GABA(A) receptor functions on SCN neurons during the circadian rhythm.
authors.affiliation: Department of Ophthalmology, Tohoku University School of Medicine, Sendai 980-8574, Japan.
authors.forename: Masahiko
authors.initials: M
authors.lastname: Shimura
authors.forename: Norio
authors.initials: N
authors.lastname: Akaike
authors.forename: Nobutoshi
authors.initials: N
authors.lastname: Harata
mesh_terms: D000818:Animals; D002712:Chlorides / Q000378:metabolism* / Q000502:physiology; D002940:Circadian Rhythm; D004553:Electric Conductivity; D005260:Female; D006096:Gramicidin; D066298:In Vitro Techniques; D007425:Intracellular Membranes / Q000378:metabolism*; D007476:Ionophores; D008297:Male; D009474:Neurons / Q000378:metabolism*; D009761:Nystatin; D018408:Patch-Clamp Techniques; D051381:Rats; D017208:Rats, Wistar; D011963:Receptors, GABA-A / Q000502:physiology; D013493:Suprachiasmatic Nucleus / Q000166:cytology / Q000378:metabolism*; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology
chemical_list: D002712:Chlorides; D007476:Ionophores; D011963:Receptors, GABA-A; D009761:Nystatin; D006096:Gramicidin; D005680:gamma-Aminobutyric Acid