ADP, ATP, ethanol, and EDTA stimulate mitochondrial Mg2+ efflux in a mannitol medium. panel A, the medium contained 0.6 M mannitol, 10 mM HEPES (TEA+), pH 7.20 and 0.1 mM decavanadate (Na+). Where indicated 1 mM ethanol, 2 mM ATP (Na+), 2 mM ADP (Na+), and 2 mM EDTA (K+) were present. panel B, the medium was the same as for panel A. The amount of mitochondrial Mg2+ was measured 6 min. after suspension varying the ADP and ATP concentrations as indicated.