Hansson 2010 J Biol Chem: Difference between revisions
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{{Publication | {{Publication | ||
|title=Hansson | |title=Hansson Magnus J, Morota S, Teilum M, Mattiasson G, Uchino H, Elmer E (2010) Increased potassium conductance of brain mitochondria induces resistance to permeability transition by enhancing matrix volume. J Biol Chem 285:741-50. | ||
|info=[http://www.ncbi.nlm.nih.gov/pubmed/19880514 PMID: 19880514 Open Access] | |info=[http://www.ncbi.nlm.nih.gov/pubmed/19880514 PMID: 19880514 Open Access] | ||
|authors=Hansson | |authors=Hansson Magnus J, Morota S, Teilum M, Mattiasson G, Uchino H, Elmer E | ||
|year=2010 | |year=2010 | ||
|journal=J Biol Chem | |journal=J Biol Chem | ||
|abstract=Modulation of K<sup>+</sup> conductance of the inner mitochondrial membrane has been proposed to mediate preconditioning in ischemia-reperfusion injury. The mechanism is not entirely understood, but it has been linked to a decreased activation of mitochondrial permeability transition (mPT). In the present study K<sup>+</sup> channel activity was mimicked by picomolar concentrations of valinomycin. Isolated brain mitochondria were exposed to continuous infusions of calcium. Monitoring of extramitochondrial Ca<sup>2+</sup> and mitochondrial respiration provided a quantitative assay for mPT sensitivity by determining calcium retention capacity (CRC). Valinomycin and cyclophilin D inhibition separately and additively increased CRC. Comparable degrees of respiratory uncoupling induced by increased K<sup>+</sup> or H<sup>+</sup> conductance had opposite effects on mPT sensitivity. Protonophores dose-dependently decreased CRC, demonstrating that so-called mild uncoupling was not beneficial per se. The putative mitoK(ATP) channel opener diazoxide did not mimic the effect of valinomycin. An alkaline matrix pH was required for mitochondria to retain calcium, but increased K<sup>+</sup> conductance did not result in augmented DeltapH. The beneficial effect of valinomycin on CRC was not mediated by H<sub>2</sub>O<sub>2</sub>-induced protein kinase Cepsilon activation. Rather, increased K<sup>+</sup>conductance reduced H<sub>2</sub>O<sub>2</sub> generation during calcium infusion. Lowering the osmolarity of the buffer induced an increase in mitochondrial volume and improved CRC similar to valinomycin without inducing uncoupling or otherwise affecting respiration. We propose that increased potassium conductance in brain mitochondria may cause a direct physiological effect on matrix volume inducing resistance to pathological calcium challenges. | |abstract=Modulation of K<sup>+</sup> conductance of the inner mitochondrial membrane has been proposed to mediate preconditioning in ischemia-reperfusion injury. The mechanism is not entirely understood, but it has been linked to a decreased activation of mitochondrial permeability transition (mPT). In the present study K<sup>+</sup> channel activity was mimicked by picomolar concentrations of valinomycin. Isolated brain mitochondria were exposed to continuous infusions of calcium. Monitoring of extramitochondrial Ca<sup>2+</sup> and mitochondrial respiration provided a quantitative assay for mPT sensitivity by determining calcium retention capacity (CRC). Valinomycin and cyclophilin D inhibition separately and additively increased CRC. Comparable degrees of respiratory uncoupling induced by increased K<sup>+</sup> or H<sup>+</sup> conductance had opposite effects on mPT sensitivity. Protonophores dose-dependently decreased CRC, demonstrating that so-called mild uncoupling was not beneficial per se. The putative mitoK(ATP) channel opener diazoxide did not mimic the effect of valinomycin. An alkaline matrix pH was required for mitochondria to retain calcium, but increased K<sup>+</sup> conductance did not result in augmented DeltapH. The beneficial effect of valinomycin on CRC was not mediated by H<sub>2</sub>O<sub>2</sub>-induced protein kinase Cepsilon activation. Rather, increased K<sup>+</sup>conductance reduced H<sub>2</sub>O<sub>2</sub> generation during calcium infusion. Lowering the osmolarity of the buffer induced an increase in mitochondrial volume and improved CRC similar to valinomycin without inducing uncoupling or otherwise affecting respiration. We propose that increased potassium conductance in brain mitochondria may cause a direct physiological effect on matrix volume inducing resistance to pathological calcium challenges. | ||
|keywords=Ischemia-reperfusion injury, K(+) channel, | |keywords=Ischemia-reperfusion injury, K(+) channel, Mitochondrial permeability transition (mPT), Isolated brain mitochondria, Extramitochondrial Ca(2+), Calcium retention capacity (CRC), Uncoupling | ||
|mipnetlab= | |mipnetlab=SE Lund Elmer E, JP Tokyo Uchino H | ||
|discipline=Mitochondrial Physiology | |discipline=Mitochondrial Physiology | ||
}} | }} | ||
{{Labeling | {{Labeling | ||
|area=Respiration | |area=Respiration | ||
|injuries=Ischemia-reperfusion, Permeability transition | |||
|organism=Rat | |organism=Rat | ||
|tissues=Nervous system | |tissues=Nervous system | ||
|preparations=Isolated | |preparations=Isolated mitochondria | ||
|enzymes=Inner | |enzymes=Inner mt-membrane transporter | ||
|couplingstates=LEAK, OXPHOS, ET | |||
|couplingstates=LEAK, OXPHOS, | |||
|instruments=Oxygraph-2k, TIP2k | |instruments=Oxygraph-2k, TIP2k | ||
|additional=JP, | |||
|discipline=Mitochondrial Physiology | |discipline=Mitochondrial Physiology | ||
}} | }} |
Latest revision as of 17:34, 25 February 2020
Hansson Magnus J, Morota S, Teilum M, Mattiasson G, Uchino H, Elmer E (2010) Increased potassium conductance of brain mitochondria induces resistance to permeability transition by enhancing matrix volume. J Biol Chem 285:741-50. |
Hansson Magnus J, Morota S, Teilum M, Mattiasson G, Uchino H, Elmer E (2010) J Biol Chem
Abstract: Modulation of K+ conductance of the inner mitochondrial membrane has been proposed to mediate preconditioning in ischemia-reperfusion injury. The mechanism is not entirely understood, but it has been linked to a decreased activation of mitochondrial permeability transition (mPT). In the present study K+ channel activity was mimicked by picomolar concentrations of valinomycin. Isolated brain mitochondria were exposed to continuous infusions of calcium. Monitoring of extramitochondrial Ca2+ and mitochondrial respiration provided a quantitative assay for mPT sensitivity by determining calcium retention capacity (CRC). Valinomycin and cyclophilin D inhibition separately and additively increased CRC. Comparable degrees of respiratory uncoupling induced by increased K+ or H+ conductance had opposite effects on mPT sensitivity. Protonophores dose-dependently decreased CRC, demonstrating that so-called mild uncoupling was not beneficial per se. The putative mitoK(ATP) channel opener diazoxide did not mimic the effect of valinomycin. An alkaline matrix pH was required for mitochondria to retain calcium, but increased K+ conductance did not result in augmented DeltapH. The beneficial effect of valinomycin on CRC was not mediated by H2O2-induced protein kinase Cepsilon activation. Rather, increased K+conductance reduced H2O2 generation during calcium infusion. Lowering the osmolarity of the buffer induced an increase in mitochondrial volume and improved CRC similar to valinomycin without inducing uncoupling or otherwise affecting respiration. We propose that increased potassium conductance in brain mitochondria may cause a direct physiological effect on matrix volume inducing resistance to pathological calcium challenges. โข Keywords: Ischemia-reperfusion injury, K(+) channel, Mitochondrial permeability transition (mPT), Isolated brain mitochondria, Extramitochondrial Ca(2+), Calcium retention capacity (CRC), Uncoupling
โข O2k-Network Lab: SE Lund Elmer E, JP Tokyo Uchino H
Labels: MiParea: Respiration
Stress:Ischemia-reperfusion, Permeability transition Organism: Rat Tissue;cell: Nervous system Preparation: Isolated mitochondria Enzyme: Inner mt-membrane transporter
Coupling state: LEAK, OXPHOS, ET
HRR: Oxygraph-2k, TIP2k
JP