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Calcium encoding (also referred to as Ca2+ encoding or calcium information processing) is an intracellular signaling pathway used by many cells to transfer, process and encode external information detected by the cell. In cell physiology, external information is often converted into intracellular calcium dynamics. The concept of calcium encoding explains how Ca2+ ions act as intracellular messengers, relaying information within cells to regulate their activity.〔 Given the ubiquity of Ca2+ ions in cell physiology, Ca2+ encoding has also been suggested as a potential tool to characterize cell physiology in health and disease.〔〔〔 The mathematical bases of Ca2+ encoding have been pioneered by work of (Joel Keizer ) and (Hans G. Othmer ) on calcium modeling in the 1990s and more recently they have been revisited by Eshel Ben-Jacob, (Herbert Levine ) and co-workers. ==AM, FM and AFM calcium encoding== Although elevations of Ca2+ are necessary for it to act as a signal, prolonged increases of the concentration of Ca2+ in the cytoplasm can be lethal for the cell. Thus cells avoid death usually delivering Ca2+ signals as brief transients - i.e. Ca2+ elevations followed by a rapid decay - or in the form of oscillations. In analogy with Information Theory, either the amplitude or the frequency or both features of these Ca2+ oscillations define the Ca2+ encoding mode. Therefore three classes of Ca2+ signals can be distinguished on the basis of their encoding mode:〔〔〔 * * AM encoding Ca2+ signals: when the strength of the stimuli is encoded by ''amplitude modulations'' of Ca2+ oscillations. In other words, stimuli of the same nature but of different strength are associated with different amplitudes of Ca2+ oscillations but the frequencies of these oscillations are similar; * * FM encoding Ca2+ signals: when the strength of the stimuli is encoded by ''frequency modulations'' of Ca2+ oscillations. In other words, stimuli of the same nature but of different strength are associated with different frequencies of Ca2+ oscillations but the amplitudes of these oscillations are similar; * * AFM encoding Ca2+ signals: when ''both'' AM and FM encoding modes coexist. Experiments and biophysical modeling, show that the mode of calcium encoding varies from cell to cell, and that a given cell could even show different types of calcium encoding for different patho-physiological conditions.〔〔 This could ultimately provide a crucial tool in medical diagnostics, to characterize, recognize and prevent diseases.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Calcium encoding」の詳細全文を読む スポンサード リンク
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