Evidence for Hexagonal II Phase Lipid Involvement in Mitochondrial Ca²⁺ Movements

Abstract

The release of matrix Ca²⁺ from mitochondria is induced by a variety of compounds, eg. palmitoyl-CoA (P-CoA) (1). Addition of these compounds to mitochondria which contain Ca²⁺ produces a period of mitochondrial Ca²⁺ release and reaccumulation, i.e. Ca²⁺ cycling, followed by large amplitude swelling, inner membrane depolarization and net Ca²⁺ release (2). These phenomena occur only if inorganic phosphate is in the reaction medium (3). Whether these observations are related to the mechanism(s) through which the mitochondrion contributes to Ca²⁺ homeostasis in the normal cell remains to be determined. However, under pathological conditions such as ischemia this process of Ca²⁺ release may relate to matrix Ca²⁺ content and mitochondrial volume changes observed (4).