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Dehydrogenase activation by Ca2+ in cells and tissues.
1Laboratory of Cardiovascular Science, National Institute on Aging, Baltimore, Maryland 21224.
Journal of Bioenergetics and Biomembranes
|December 1, 1991
Summary
Calcium (Ca2+) activates intramitochondrial dehydrogenases, linking tissue work to ATP production. This study explores this control model in cardiac cells, showing Ca2+ changes modulate dehydrogenase activity.
Area of Science:
- Biochemistry
- Cellular Physiology
- Mitochondrial Function
Background:
- Mitochondrial dehydrogenases are activated by calcium (Ca2+), linking cellular work to ATP production.
- This activation influences pyruvate dehydrogenase and the tricarboxylate cycle, key components of oxidative phosphorylation.
Purpose of the Study:
- To examine the model of oxidative phosphorylation control by intramitochondrial Ca2+.
- To investigate mitochondrial function in situ within cardiac myocytes and the intact heart.
Main Methods:
- Utilized fluorescent Ca2+ chelating agents (indo-1, fura-2) for quantitative analysis of isolated mitochondria.
- Employed a novel technique by Miyata et al. to measure free intramitochondrial Ca2+ in single cardiac myocytes.
Main Results:
- Demonstrated a quantitative dependence of dehydrogenase activity on free intramitochondrial Ca2+ concentrations in isolated mitochondria.
- Showed that electrical excitation of cardiac myocytes alters free intramitochondrial Ca2+ levels significantly.
Conclusions:
- Intramitochondrial Ca2+ concentration changes substantially modulate dehydrogenase activity in cardiac myocytes.
- This Ca2+-mediated regulation is a key factor in controlling mitochondrial ATP production during varying work demands.