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Characteristics of the substrate‐free mitochondria
Author(s) -
Leem Chae Hun,
Ho Quynh Mai,
Lee Jeong Hoon,
Kim In Young,
Youm Jae Boum
Publication year - 2020
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2020.34.s1.03679
Subject(s) - oligomycin , biophysics , chemistry , substrate (aquarium) , mitochondrion , hyperpolarization (physics) , diazoxide , atpase , adenosine triphosphate , depolarization , atp synthase , biochemistry , stereochemistry , biology , enzyme , ecology , nuclear magnetic resonance spectroscopy , insulin , endocrinology
Mitochondria are critical organelle to convert the metabolites to the life‐essential chemicals, ATP. For serving the role, the mitochondria have very peculiar steps from metabolites to ATP formation. Usually the Ψm was regarded as zero without the mitochondrial substrate or in the presence of uncoupler. However, we found there still considerable Ψm was existed even in those conditions. So basic scheme of the generation of Ψm is hampered and the question how to explain this phenomena remains. For attacking these problems, we used a multiparametric microfluorometric system to monitor NADH, FAD, and TMRE fluorescence, simultaneously and developed a measurement method of Ψm quantitatively. The Ψm in substrate free conditions was around −60 mV. The application of ATP generated considerable hyperpolarization. The application of K ATP channel opener, diazoxide (DZX), could depolarize Ψm. When K + was replaced with meglumin, the Ψm was slightly hyperpolarized and the effect of DZX was abolished. The K ATP channel blockers did not have any effect. The application of ATP hyperpolarize Ψm, however, ADP or AMP didn’t. Oligomycin blocked the effect of ATP. Interestingly, oligomycin depolarized the resting Ψm considerably. The effect of ATP was not affected by DZX. The replacement K + with meglumin slowed the ATP‐induced change of Ψm and made it transient. The return to K + medium recovered the effect of ATP. From these results, the Ψm in substrate‐free conditions was not zero and K + may particpate in the formation of the resting Ψm. The F1,F0‐ATPase may participate on the formation of the resting Ψm. K + may be an important modulator for F1,F0‐ATPase acitivity. The F1,F0‐ATPase and K + flux might contribute the formation of the resting Ψm but it still need further study on them. Support or Funding Information This work is supported by NRF‐2015M3A9B6028310 and NRF‐2016M3C1A6936605.