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Permeability transition pore closure promoted by quinine
1Departamento de Patologia Clinica, NMCE, Faculdade de Ciências Médicas, Universidade Estadual de Campinas, SP, Brasil.
Journal of Bioenergetics and Biomembranes
|August 17, 1999
Summary
Quinine inhibits calcium (Ca2+)-induced mitochondrial permeability transition by displacing Ca2+ from the inner membrane. This action closes the permeability transition pore, preventing mitochondrial swelling and dysfunction.
Area of Science:
- Biochemistry
- Cell Biology
- Mitochondrial Physiology
Background:
- Mitochondrial membrane permeability transition (MPT) is a critical process regulated by calcium (Ca2+).
- Dysregulation of MPT contributes to various pathologies, making it a target for therapeutic intervention.
Purpose of the Study:
- To investigate the effect of quinine on Ca2+-induced MPT.
- To elucidate the mechanism by which quinine affects Ca2+ binding and MPT.
Main Methods:
- Dose-dependent inhibition assays of MPT by quinine.
- Competition experiments to assess Ca2+ displacement by quinine.
- Mitochondrial swelling assays using phenylarsine oxide and poly(ethylene glycol) 2000.
Main Results:
- Quinine inhibited Ca2+-induced MPT in a dose-dependent manner.
- Competition studies indicated quinine displaces Ca2+ from the inner mitochondrial membrane.
- Quinine specifically inhibited Ca2+-dependent, but not Ca2+-independent, mitochondrial swelling.
- Quinine induced permeability transition pore closure, similar to Ca2+ chelators.
Conclusions:
- Quinine dislodges Ca2+ from its binding site on mitochondrial proteins.
- This displacement prevents Ca2+-triggered pore opening and subsequent MPT.
- Quinine shows potential as a modulator of mitochondrial function by interfering with Ca2+ regulation.