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Characterization by Hg2+ of two different pathways for mitochondrial Ca2+ release
1Departamento de Bioquímica, Instituto Nacional de Cardiología, Ignacio Chávez, Mexico City.
Biochimica Et Biophysica Acta
|November 17, 1989
Summary
Mercury ions (Hg2+) trigger calcium (Ca2+) release from kidney mitochondria. The release mechanism varies with Hg2+ binding levels, indicating distinct pathways influenced by mercury interactions with mitochondrial membranes.
Area of Science:
- Mitochondrial biochemistry
- Toxicology
- Membrane transport
Background:
- Kidney mitochondria accumulate cations like calcium (Ca2+) and strontium (Sr2+).
- Mercury ions (Hg2+) are known to interact with biological membranes and proteins.
Purpose of the Study:
- To investigate the effect of mercury ions (Hg2+) on cation efflux from kidney mitochondria.
- To characterize the mechanisms of Ca2+ and Sr2+ release induced by Hg2+.
Main Methods:
- Incubation of loaded kidney mitochondria with varying concentrations of Hg2+.
- Measurement of cation efflux kinetics under different temperature conditions.
- Identification of Hg2+-binding proteins using sodium dodecyl sulfate gel electrophoresis and radiolabeling.
Main Results:
- Hg2+ induces rapid Ca2+ efflux from mitochondria.
- Two distinct Ca2+ efflux mechanisms were identified, dependent on the extent of Hg2+ binding to the inner mitochondrial membrane.
- At high Hg2+ levels, Ca2+ and Sr2+ efflux was temperature-insensitive, while at low levels, it was temperature-dependent.
- Hg2+ binds to mitochondrial proteins with apparent molecular masses of 150 kDa and 37-25 kDa, including specific proteins around 41 and 26 kDa.
Conclusions:
- The binding of Hg2+ to kidney mitochondria triggers cation release through at least two distinct mechanisms.
- The characteristics of cation efflux are modulated by the amount of Hg2+ bound, suggesting differential interactions with mitochondrial components.