Intracellular Calcium Spikes in Rat Suprachiasmatic Nucleus Neurons Induced by BAPTA-Based Calcium Dyes

Circadian rhythms in spontaneous action potential (AP) firing frequencies and in cytosolic free calcium concentrations have been reported for mammalian circadian pacemaker neurons located within the hypothalamic suprachiasmatic nucleus (SCN). Also reported is the existence of “Ca2+ spikes” (i.e., [Ca2+]c transients having a bandwidth of 10~100 seconds) in SCN neurons, but it is unclear if these SCN Ca2+ spikes are related to the slow circadian rhythms.