title: Coding efficiency and information rates in transmembrane signaling.
abstract: A variety of cell types responds to hormonal stimuli by repetitive spikes in the intracellular concentration of calcium ([Ca(2+)](i)) which have been demonstrated to encode information in their frequency, amplitude, and duration. These [Ca(2+)](i)-spike trains are able to specifically regulate distinct cellular functions. Using a mathematical model for receptor-controlled [Ca(2+)](i) oscillations in hepatocytes we investigate the encoding of fluctuating hormonal signals in [Ca(2+)](i)-spike trains. The transmembrane information transfer is quantified by using an information-theoretic reverse-engineering approach which allows to reconstruct the dynamic hormonal stimulus from the [Ca(2+)](i)-spike trains. This approach allows to estimate the accuracy of coding as well as the rate of transmembrane information transfer. We found that up to 87% of the dynamic stimulus information can be encoded in the [Ca(2+)](i)-spike train at a maximum information transfer rate of 1.1 bit per [Ca(2+)](i)-spike. These numerical results for humoral information transfer are in the same order as in a number of sensory neuronal systems despite several orders of magnitude different time scales of operation suggesting a universal principle of information processing in both biological systems.
authors.affiliation: Computational Endocrinology Group, Department of Clinical Endocrinology, Medical School Hanover, Carl-Neuberg Str. 1, 30625, Hanover, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Prank
authors.forename: F
authors.initials: F
authors.lastname: Gabbiani
authors.forename: G
authors.initials: G
authors.lastname: Brabant
mesh_terms: D000200:Action Potentials; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D053496:Inositol 1,4,5-Trisphosphate Receptors; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*
chemical_list: D015220:Calcium Channels; D053496:Inositol 1,4,5-Trisphosphate Receptors; D018160:Receptors, Cytoplasmic and Nuclear; D002118:Calcium