Ca2+-induced Ca2+ release supports the relay mode of activity in thalamocortical cells.
Ca2+ ions play an important role during rhythmic bursting of thalamocortical neurons within sleep. The function of Ca2+ during the tonic relay mode of these neurons during wakefulness is less clear. Here, we report that tonic activity in thalamocortical cells results in an increase in the intracellular Ca2+ concentration and subsequent release of Ca2+ from intracellular stores mediated via ryanodine receptors (RyRs). Blockade of Ca2+ release shifted the regular firing of single action potentials toward the generation of spike clusters. Regular spike firing and intracellular Ca2+ release thus appear to be functionally coupled in a positive feedback manner, thereby supporting the relay mode of thalamocortical cells during wakefulness. Regulatory influences may be coupled to this system via the cyclic ADP ribose pathway.
Budde
T
T
Institut für Physiologie, Otto-von-Guericke-Universität, Magdeburg, Federal Republic of Germany. thomas.budde@medizin.uni-magdeburg.de
Sieg
F
F
Braunewell
K H
KH
Gundelfinger
E D
ED
Pape
H C
HC
D000200:Action Potentials / Q000502:physiology; D000818:Animals; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology*; D002540:Cerebral Cortex / Q000166:cytology / Q000502:physiology*; D066298:In Vitro Techniques; D007425:Intracellular Membranes / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000502:physiology; D009994:Osmolar Concentration; D051381:Rats; D020318:Rats, Long-Evans; D019837:Ryanodine Receptor Calcium Release Channel / Q000502:physiology; D013788:Thalamus / Q000166:cytology / Q000502:physiology*
D009419:Nerve Tissue Proteins; D019837:Ryanodine Receptor Calcium Release Channel; D002118:Calcium