T A Kavalenia, E A Lapshina, T V Ilyich, Hu-Cheng Zhao, I B Zavodnik
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引用次数: 0
Abstract
The function of mitochondria as a regulator of myocyte calcium homeostasis has been extensively discussed. The aim of the present work was further clarification of the details of modulation of the functional activity of rat cardiac mitochondria by exogenous Ca2+ ions either in the absence or in the presence of the plant flavonoid naringin. Low free Ca2+ concentrations (40-250 nM) effectively inhibited the respiratory activity of heart mitochondria, remaining unaffected the efficacy of oxygen consumption. In the presence of high exogenous Ca2+ ion concentrations (Ca2+ free was 550 µM), we observed a dramatic increase in mitochondrial heterogeneity in size and electron density, which was related to calcium-induced opening of the mitochondrial permeability transition pores (MPTP) and membrane depolarization (Ca2+free ions were from 150 to 750 µM). Naringin partially prevented Ca2+-induced cardiac mitochondrial morphological transformations (200 µM) and dose-dependently inhibited the respiratory activity of mitochondria (10-75 µM) in the absence or in the presence of calcium ions. Our data suggest that naringin (75 µM) promoted membrane potential dissipation, diminishing the potential-dependent accumulation of calcium ions by mitochondria and inhibiting calcium-induced MPTP formation. The modulating effect of the flavonoid on Ca2+-induced mitochondria alterations may be attributed to the weak-acidic nature of the flavonoid and its protonophoric/ionophoric properties. Our results show that the sensitivity of rat heart mitochondria to Ca2+ ions was much lower in the case of MPTP opening and much higher in the case of respiration inhibition as compared to liver mitochondria.
期刊介绍:
Molecular and Cellular Biochemistry: An International Journal for Chemical Biology in Health and Disease publishes original research papers and short communications in all areas of the biochemical sciences, emphasizing novel findings relevant to the biochemical basis of cellular function and disease processes, as well as the mechanics of action of hormones and chemical agents. Coverage includes membrane transport, receptor mechanism, immune response, secretory processes, and cytoskeletal function, as well as biochemical structure-function relationships in the cell.
In addition to the reports of original research, the journal publishes state of the art reviews. Specific subjects covered by Molecular and Cellular Biochemistry include cellular metabolism, cellular pathophysiology, enzymology, ion transport, lipid biochemistry, membrane biochemistry, molecular biology, nuclear structure and function, and protein chemistry.