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Title: Stability of membrane potential in heart mitochondria: Single mitochondrion imaging

Abstract

Mitochondrial membrane potential ({delta}{psi} {sub m}) plays an important role in cellular activity. Although {delta}{psi} {sub m} of intracellular mitochondria are relatively stable, the recent experiments with isolated mitochondria demonstrate that individual mitochondria show frequent fluctuations of {delta}{psi} {sub m}. The current study is performed to investigate the factors that stabilize {delta}{psi} {sub m} in cells by observing {delta}{psi} {sub m} of individual isolated mitochondria with fluorescence microscopy. Here, we report that (1) the transient depolarizations are also induced for mitochondria in plasma membrane permeabilized cells, (2) almost all mitochondria isolated from porcine hearts show the transient depolarizations that is enhanced with the net efflux of protons from the matrix to the intermembrane space, and (3) ATP and ADP significantly inhibit the transient depolarizations by plural mechanisms. These results suggest that the suppression of acute alkalinization of the matrix together with the presence of ATP and ADP contributes to the stabilization of {delta}{psi} {sub m} in cells.

Authors:
 [1];  [1];  [1];  [2]
  1. Division of Biotechnology and Life Science, Institute of Symbiotic Science and Technology, Tokyo University of Agriculture and Technology, Nakacho, Koganei, Tokyo 184-8588 (Japan)
  2. Division of Biotechnology and Life Science, Institute of Symbiotic Science and Technology, Tokyo University of Agriculture and Technology, Nakacho, Koganei, Tokyo 184-8588 (Japan). E-mail: ohta@cc.tuat.ac.jp
Publication Date:
OSTI Identifier:
20798998
Resource Type:
Journal Article
Resource Relation:
Journal Name: Biochemical and Biophysical Research Communications; Journal Volume: 344; Journal Issue: 4; Other Information: DOI: 10.1016/j.bbrc.2006.03.233; PII: S0006-291X(06)00781-9; Copyright (c) 2006 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES; ADP; ATP; DEPOLARIZATION; FLUORESCENCE; HEART; MICROSCOPY; MITOCHONDRIA; PROTONS

Citation Formats

Uechi, Yukiko, Yoshioka, Hisashi, Morikawa, Daisuke, and Ohta, Yoshihiro. Stability of membrane potential in heart mitochondria: Single mitochondrion imaging. United States: N. p., 2006. Web. doi:10.1016/j.bbrc.2006.03.233.
Uechi, Yukiko, Yoshioka, Hisashi, Morikawa, Daisuke, & Ohta, Yoshihiro. Stability of membrane potential in heart mitochondria: Single mitochondrion imaging. United States. doi:10.1016/j.bbrc.2006.03.233.
Uechi, Yukiko, Yoshioka, Hisashi, Morikawa, Daisuke, and Ohta, Yoshihiro. Fri . "Stability of membrane potential in heart mitochondria: Single mitochondrion imaging". United States. doi:10.1016/j.bbrc.2006.03.233.
@article{osti_20798998,
title = {Stability of membrane potential in heart mitochondria: Single mitochondrion imaging},
author = {Uechi, Yukiko and Yoshioka, Hisashi and Morikawa, Daisuke and Ohta, Yoshihiro},
abstractNote = {Mitochondrial membrane potential ({delta}{psi} {sub m}) plays an important role in cellular activity. Although {delta}{psi} {sub m} of intracellular mitochondria are relatively stable, the recent experiments with isolated mitochondria demonstrate that individual mitochondria show frequent fluctuations of {delta}{psi} {sub m}. The current study is performed to investigate the factors that stabilize {delta}{psi} {sub m} in cells by observing {delta}{psi} {sub m} of individual isolated mitochondria with fluorescence microscopy. Here, we report that (1) the transient depolarizations are also induced for mitochondria in plasma membrane permeabilized cells, (2) almost all mitochondria isolated from porcine hearts show the transient depolarizations that is enhanced with the net efflux of protons from the matrix to the intermembrane space, and (3) ATP and ADP significantly inhibit the transient depolarizations by plural mechanisms. These results suggest that the suppression of acute alkalinization of the matrix together with the presence of ATP and ADP contributes to the stabilization of {delta}{psi} {sub m} in cells.},
doi = {10.1016/j.bbrc.2006.03.233},
journal = {Biochemical and Biophysical Research Communications},
number = 4,
volume = 344,
place = {United States},
year = {Fri Jun 16 00:00:00 EDT 2006},
month = {Fri Jun 16 00:00:00 EDT 2006}
}
  • In the present report we will summarize the evidence for the isolation of a 3000-dalton protein from the inner mitochondrial membrane of calf heart (a more detailed report is in Reference 1). The calcium carrier isolated (coined by us calciphorin) translocates Ca/sup 2 +/ through an organic solvent in a Pressman cell only when it is driven by a hydrogen ion gradient. The carrier appears to form a neutral complex with calcium and exchanges Ca/sup 2 +/ with hydrogen ions. The molecular weight of this protein was estimated by urea-SDS gel electrophoresis, and known low molecular weight standards were usedmore » as reference. Our attempt to isolate the Ca/sup 2 +/ carrier was for the purpose of understanding the molecular mechanism of Ca/sup 2 +/ transport in mitochondria. This phenomenon is essentially unsolved after more than fifteen years of extensive study. Several completely dissimilar mechanisms have been proposed. Despite the disagreement in the mechanism of Ca/sup 2 +/ transport, it is almost generally accepted that the transport of Ca/sup 2 +/ across the inner mitochondrial membrane is a carrier-mediated process.« less
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  • The authors have tested directly the effect of Helminthosporium maydis T (Hmt) toxin and various analogs on the membrane potential formed in mitochondria isolated from a Texas (T) cytoplasmic male-sterile and a normal (N) corn. ATP, malate or succinate generated a membrane potential (negative inside) as monitored by the absorbance change of a cationic dye, safranine. The relative membrane potential (..delta.. psi) could also be detected indirectly as /sup 45/Ca/sup 2 +/ uptake. Hmt toxin added to T mitochondria dissipated the steady state delta psi similar to addition of a protonophore, carbonyl cyanide m-chlorophenylhydrazone (CCCP). Toxin analogs (Cpd XIII: C/submore » 41/H/sub 68/O/sub 12/ and Cpd IV: C/sub 25/H/sub 44/O/sub 6/), reduced native toxin (RT2C: C/sub 41/H/sub 84/O/sub 13/) and Pm toxin (band A: C/sub 33/H/sub 60/O/sub 8/, produced by the fungus, Phyllosticta maydis) were effective in dissipating ..delta.. psi and decreasing Ca/sup 2 +/ uptake with the following order: Pm (100) >> HmT (23-30) > Cpd XIII (11-25) >> RT2C (0.4-1.8) > Cpd IV (0.2-1.0). In contrast, the toxins and analogs had no effect on delta psi formed in N mitochondria. The striking similarities of the HmT toxin (band 1: C/sub 41/H/sub 68/O/sub 13/) and Cpd XIII on T mitochondrial activities provide strong evidence supporting the correctness of the polyketol structure assigned to the native toxin. Since the ..delta.. psi in energized mitochondria is caused mainly by the electrogenic extrusion of H/sup +/, the results support the idea that HmT toxin increases membrane permeability of T mitochondria to H/sup +/. The host specificity of the toxin suggests that an interaction with unique target site(s) on the inner mitochondrial membrane of T corn causes H/sup +/ leakage.« less
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