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We study the influence of the structural diversity of cells on subthreshold agonist signals in coupled hepatocytes systems. The variance of the cellular structural parameter sigma is employed to characterize the structural diversity. It is found that structural diversity enhances the cellular ability to detect extracellular weak signals through intracellular Ca2+ oscillations and the regularity of Ca2+ spikes undergoes a maximum with a variation of sigma, indicating the occurrence of structural-diversity-induced coherence resonance. Furthermore, the effects of the level of subthreshold stimulus and junctional coupling strength on the behavior of Ca2+ dynamics are also considered. Analysis indicates that these phenomena have inherent relevance to both the bifurcation feature of a single cell and intercellular interaction through junctional coupling. Our findings may exhibit that structural diversity plays a constructive role in biological systems.

We have investigated how the external noise would influence the intracellular calcium signaling processes due to the existence of internal noise in small systems. Using chemical Langevin equations, we demonstrate numerically that the behavior of 'system size bi-resonance' induced by internal noise will change with the external noise intensity in different regions, indicating the occurrence of selective effects of external noise. Meanwhile, cell system may also automatically select an optimal cell size to obtain the best performance in the presence of external noise. These results may imply that such selective-effect phenomenon should have some inherent relevance with the distinct deterministic bifurcation features of the system.

We have studied the collective calcium signaling behavior of an array of coupled N cells, taking into account the internal noises resulting from the small cell size V. The system's performance was characterized by the reciprocal coefficient of variance (RCV) of the calcium spike train. Two system-size resonances were observed, namely, the RCV value shows a clear peak when both N and V are optimal. Therefore, an optimal number of cells of optimal size work the best as a whole.

We have studied the collective behavior of calcium signaling in a linear array of coupled cells, taking into account the influence of internal noise. For a single cell, the performance of the stochastic calcium oscillations shows two maxima as a function of the cell size, indicating the occurrence of system size bi-resonance. When the cells are coupled together, we find that the increase of the coupling strength or the number of cells can considerably enhance the first peak, but decrease the second one. The occurrence of the bi-resonance and the distinct dependence on the coupling are shown to be relevant with regard to the system's deterministic bifurcation features.