Chelating agents and rat liver mitochondria

The chelating agents (EGTA and EDTA) and inorganic phosphate (Pi) are the most variable components of experiments involving isolated liver mitochondria. In the absence of EGTA or EDTA, swelling induced by Pi leads to rapid loss of endogenous adenine nucleotides to adenosine. Chelating agents prevent swelling and loss of adenine nucleotides. Concentrations below about 0.1 mM are ineffective. The protective effects depend on the continuous presence of the chelating agent; they are lost on washing EGTA-containing suspensions with chelating-agent-free medium. We question the accepted view that chelating agents stabilize mitochondria by binding Ca2+ to prevent activation of phospholipase.