[Calcium, the atom triggering life and cellular function].

Although during the last three decades phosphorylation and dephosphorylation systems have been pointed out as the mechanisms used by living cells to control biological processes, it seems that calcium dynamics is the phenomenon that precedes and controls protein activation by the introduction of phosphate groups into distinct protein structures. The process begins with activation of calcium channels that allows the influx of the ion, which once inside the cell leads to calcium-calmodulin complex, a molecule capable of triggering activation of distinct proteinkinases. Thus, the cell in addition to suffering a change in polarity enhances neuroconduction and release of different substances such as hormones and para-hormones, facilitates intra- and intercellular communication, and exerts determinant influence on phenotypic expression by means of promotion of immediate and mediate response genes. Ionic conformational calcium runs short- and long-term facilitation mechanisms, exerting its influence on control of memory through homosynaptic depression and hetersynaptic facilitation processes; triggers autophosphorylation of several enzymes leading and enhancing cellular activity and participates in signal transduction and decodification. Calcium influx rate activates certain groups of phosphatases capable of inhibiting autophosphorylation processes, only as a negative feedback mechanism. In addition, ionic calcium also participates in the "cross-activate" mechanism of proteinkinases A and G, influencing to production of systemic and central nervous system nitric oxide. On these bases, it is possible to guess that future pharmacologic interventions on calcium fluxes could be of invaluable importance in prevention and control of a number of distinct physiopathologic events.