Timescales of IP^sub 3^-Evoked Ca^sup 2+^ Spikes Emerge from Ca^sup 2+^ Puffs Only at the Cellular Level

The behavior of biological systems is determined by the properties of their component molecules, but the interactions are usually too complex to understand fully how molecular behavior generates cellular behavior. ... signaling by inositol trisphosphate receptors (...) offers an opportunity to understand this relationship because the cellular behavior is defined largely by ...-mediated interactions between ... ... released by a cluster of ... (giving a local ... puff) diffuses and ignites the behavior of neighboring clusters (to give repetitive global ... spikes). We use total internal reflection fluorescence microscopy of two mammalian cell lines to define the temporal relationships between ... puffs (interpuff intervals, IPI) and ... spikes (interspike intervals) evoked by flash photolysis of caged ... We find that IPI are much shorter than interspike intervals, that puff activity is stochastic with a recovery time that is much shorter than the refractory period of the cell, and that IPI are not periodic. We conclude that ... spikes do not arise from oscillatory dynamics of ... clusters, but that repetitive ... spiking with its longer timescales is an emergent property of the dynamics of the whole cluster array. (ProQuest: ... denotes formulae/symbols omitted.)