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Interaction of Sr2+ with Ca2+-induced Ca2+ release in mitochondria
1Department of Medical Chemistry, University of Helsinki, Finland.
Journal of Bioenergetics and Biomembranes
|December 1, 1988
Summary
Strontium (Sr2+) influences calcium (Ca2+) release from rat liver mitochondria. Sr2+ inhibits Ca2+ release when added with or after Ca2+, but stimulates it when added beforehand, suggesting a non-phospholipase mechanism.
Area of Science:
- Mitochondrial Physiology
- Ion Transport Mechanisms
- Biochemistry
Background:
- Mitochondria accumulate calcium (Ca2+), but can spontaneously release it above a threshold.
- Strontium (Sr2+) and Manganese (Mn2+) are typically retained by mitochondria.
- Ca2+-induced mitochondrial Ca2+ release is linked to phospholipase A activation.
Purpose of the Study:
- To investigate the interaction of Sr2+ with the Ca2+ release process in respiring rat liver mitochondria.
- To determine if Sr2+ affects the Ca2+-induced release of accumulated Ca2+.
- To explore the mechanism underlying Ca2+ release, particularly its relationship with phospholipase A.
Main Methods:
- Utilizing isolated respiring rat liver mitochondria.
- Administering Ca2+ and Sr2+ at different time points relative to each other.
- Measuring mitochondrial Ca2+ content and release.
- Assessing isolated mitochondrial phospholipase A activity.
Main Results:
- Sr2+ potently inhibited or reversed Ca2+ release when added simultaneously with or shortly after Ca2+.
- Conversely, pre-incubation with Sr2+ stimulated subsequent Ca2+-induced Ca2+ release.
- Isolated mitochondrial phospholipase A activity showed minimal inhibition by Sr2+.
Conclusions:
- Sr2+ exhibits a time-dependent modulatory effect on mitochondrial Ca2+ release.
- The findings suggest that Ca2+-induced mitochondrial Ca2+ release may be triggered by a Ca2+-dependent mechanism distinct from phospholipase A activation.
- Further research is needed to elucidate the precise non-phospholipase pathway involved in mitochondrial Ca2+ handling.