On Transcellular Ionic Currents

Abstract

Living organisms drive electric current through themselves. The current is a flow of ions in solutions which passes through the cell via specific proteins like pumps, symports, channels and others. There is evidence that such currents convey information in excitable cells like neurons [1], a fact which sounds quite likely. However, the role of stationary currents in the generation of spatial order or pattern formation in growing and developing organisms looks at first glance more questionable. These stationary ionic currents have been described in plant, animal and microbial systems, in individual cells of unicellular and multicellular organisms, and in both embryonic and mature cells [2–6]. They enter in one region, generate ionic gradients in the cytoplasm and then exit in another part of the membrane. The problem is to know whether these currents are just a passive consequence of an unrelated asymmetry of the cell or if they play by themselves a key role in the generation of those cellular asymmetries. In the context of morphogenesis of cells, one may expect that the self-organization of ionic currents may induce differential growth or deformation of membranes, and hence play a role in tip growth or branching of such cells, in the long run (non-linear regime).