Differential coding of humoral stimuli by timing and amplitude of intracellular calcium spike trains

Syst Biol (Stevenage). 2005 Dec;152(4):263-8. doi: 10.1049/ip-syb:20050040.


The ubiquitous Ca2(+)-phosphoinositide pathway transduces extracellular signals to cellular effectors. Using a mathematical model, we simulated intracellular Ca2+ fluctuations in hepatocytes upon humoral stimulation. We estimated the information encoded about random humoral stimuli in these Ca2+ spike trains using an information-theoretic approach based on stimulus estimation methods. We demonstrate accurate transfer of information about random humoral signals with low temporal cutoff frequencies. In contrast, our results suggest that high-frequency stimuli are poorly transduced by the transmembrane machinery. We found that humoral signals are encoded in both the timing and amplitude of intracellular Ca2+ spikes. The information transmitted per spike is similar to that of sensory neuronal systems, in spite of several orders of magnitude difference in firing rate.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Action Potentials / physiology*
  • Animals
  • Calcium / metabolism*
  • Calcium Signaling / physiology*
  • Computer Simulation
  • Humans
  • Information Storage and Retrieval / methods
  • Intracellular Fluid / metabolism
  • Membrane Potentials / physiology*
  • Models, Biological*
  • Models, Statistical
  • Signal Transduction / physiology


  • Calcium