TTX-resistant Ca2+ oscillation in cultured hypothalamus: similarity to the mammalian circadian pacemaker.
Dissociated cultures of rat hypothalamic cells showed spontaneous oscillations in intracellular Ca2+ with periods of 5-8 s (ultradian rhythm). Replacement of H2O by deuterium oxide in the culture medium lengthened the period of this oscillation, while tetrodotoxin did not inhibit the deuterium oxide sensitive Ca2+ oscillation. Since these characteristics resemble those of the mammalian circadian pacemaker, the ultradian Ca2+ rhythms may be involved in the circadian rhythm or have a similar rhythm generation mechanism. The gap junction inhibitor, halothane, stopped this oscillation. Gap junctions may be necessary in order to generate rhythmic oscillations.
Yamazaki
S
S
Department of Molecular and Cellular Neurobiology, Tokyo Metropolitan Institute for Neuroscience, Japan.
Inouye
S T
ST
Kuroda
Y
Y
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D002940:Circadian Rhythm; D017666:Deuterium Oxide / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D017629:Gap Junctions / Q000187:drug effects; D006221:Halothane / Q000494:pharmacology; D007031:Hypothalamus / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar; D013779:Tetrodotoxin / Q000494:pharmacology*
D013779:Tetrodotoxin; D017666:Deuterium Oxide; D002118:Calcium; D006221:Halothane