Millimolar concentrations of free magnesium enhance exocytosis from permeabilized rat pheochromocytoma (PC 12) cells.
The role of Mg2+ during the final steps of exocytosis was investigated using rat pheochromocytoma cells (PC12) permeabilized with bacterial pore forming toxins. Concentrations of free Mg2+ between 0.2 and 2 mM slightly lowered the basal but greatly enhanced the [3H]dopamine release elicited by 8 microM free Ca2+. Maximal effects were obtained at approximately 1 mM free Mg2+. At higher concentrations Mg2+ was less potent. Similar effects of Mg2+ were obtained in cells permeabilized either for small molecules (by alpha-toxin) or for large ones (by streptolysin O). It is concluded that millimolar concentrations of cytoplasmic Mg2+ play an important role in Ca2+ triggered exocytosis.
Wegenhorst
U
U
Abteilung Anatomie und Zellbiologie, Universität Ulm, F.R.G.
Gratzl
M
M
Föhr
K J
KJ
Ahnert-Hilger
G
G
D000818:Animals; D004298:Dopamine / Q000493:pharmacokinetics*; D005089:Exocytosis / Q000187:drug effects*; D008274:Magnesium / Q000494:pharmacology*; D010673:Pheochromocytoma; D051381:Rats; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*
D008274:Magnesium; D004298:Dopamine