Mechanisms of Mg2+ influx, efflux and intracellular 'muffling' in leech neurones and glial cells.
Mg2+ is known to influence conductance and gating properties of a multitude of ion channels and is thus able to modulate synaptic transmission. Therefore, a tight regulation of the intracellular free Mg2+ concentration ([Mg2+]i) in neurones and glial cells is crucial for maintaining the functions of central nervous systems. [Mg2+]i is regulated through the balance of Mg2+ influx and Mg2+ efflux, together with heavy damping of [Mg2+]i changes through intracellular buffering and sequestration. To investigate the mechanisms involved in [Mg2+]i regulation, neurones and glial cells from the central nervous system of the leech Hirudo medicinalis proved to be an ideal model system. The present article summarizes the evidence for a Mg2+ influx pathway which is distinct from that for Ca2+, for a dual regulation of Mg2+ efflux (a 1 Na+/1 Mg2+ antiport and a Na(+)-independent Mg2+ efflux mechanism), for pH-dependent Mg2+ buffering through ATP and other intracellular Mg2+ binding components and for the involvement of mitochondria in intracellular Mg2+ sequestration.
Günzel
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Institut für Neurobiologie, Heinrich-Heine-Universität Düsseldorf, Germany. guenzel@uni-duesseldorf.de
Schlue
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D000818:Animals; D001692:Biological Transport; D002478:Cells, Cultured; D004553:Electric Conductivity; D004594:Electrophysiology; D006863:Hydrogen-Ion Concentration; D007477:Ions; D007865:Leeches; D008274:Magnesium / Q000378:metabolism*; D008954:Models, Biological; D009457:Neuroglia / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism
D007477:Ions; D012964:Sodium; D008274:Magnesium