ATP synthase activity is required for fructose to protect cultured hepatocytes from the toxicity of cyanide

1993 ◽  
Vol 264 (3) ◽  
pp. C709-C714 ◽  
Author(s):  
J. W. Snyder ◽  
J. G. Pastorino ◽  
A. P. Thomas ◽  
J. B. Hoek ◽  
J. L. Farber
Keyword(s):  
Membrane Potential ◽  
Protective Effect ◽  
Mitochondrial Membrane Potential ◽  
Atp Synthase ◽  
Mitochondrial Membrane ◽  
Cultured Hepatocytes ◽  
Intracellular Acidosis ◽  
Mitochondrial Atp Synthase ◽  
Carbonyl Cyanide

The contributions of the loss of the mitochondrial membrane potential (MMP) and a depletion of ATP to the genesis of lethal injury were evaluated in the killing of cultured hepatocytes by cyanide (CN). The glycolytic production of ATP from fructose (Fru) maintained the MMP and prevented the killing by CN. Inhibition of the mitochondrial ATP synthase by 0.1 micrograms/ml oligomycin (Oligo) reduced ATP stores at the same rate and to the same extent as did 1 mM CN. With Oligo there was no loss of the MMP, and the hepatocytes maintained viability over the 6 h during which CN killed all of the cells. Oligo had no effect on the rate of killing by CN. However, Oligo reversed the protective effect of Fru on CN-induced killing, a result that correlated with the loss of MMP but not with the depletion of ATP. Neither Fru nor Oligo affected the intracellular acidosis achieved with CN alone. Fru also prevented toxicity of the uncoupler carbonyl cyanide m-chlorophenylhydrazone (CCCP), a result that correlated with the preservation of MMP. Oligo potentiated the toxicity of CCCP. It is concluded that a functioning mitochondrial ATP synthase is required for the production of ATP from Fru to prevent the killing of hepatocytes by CN. The extent of killing correlated closely with changes in the MMP but not with changes in the content of ATP.

scholarly journals Bcl-xL regulates mitochondrial energetics by stabilizing the inner membrane potential

2011 ◽  
Vol 195 (2) ◽  
pp. 263-276 ◽  
Author(s):  
Ying-bei Chen ◽  
Miguel A. Aon ◽  
Yi-Te Hsu ◽  
Lucian Soane ◽  
Xinchen Teng ◽  
...  
Keyword(s):  
Membrane Potential ◽  
Mitochondrial Membrane Potential ◽  
Atp Synthase ◽  
Mitochondrial Membrane ◽  
Ion Flux ◽  
Β Subunit ◽  
Inner Mitochondrial Membrane ◽  
Two Photon Microscopy ◽  
Mitochondrial Atp Synthase ◽  
Large Fluctuations

Mammalian Bcl-xL protein localizes to the outer mitochondrial membrane, where it inhibits apoptosis by binding Bax and inhibiting Bax-induced outer membrane permeabilization. Contrary to expectation, we found by electron microscopy and biochemical approaches that endogenous Bcl-xL also localized to inner mitochondrial cristae. Two-photon microscopy of cultured neurons revealed large fluctuations in inner mitochondrial membrane potential when Bcl-xL was genetically deleted or pharmacologically inhibited, indicating increased total ion flux into and out of mitochondria. Computational, biochemical, and genetic evidence indicated that Bcl-xL reduces futile ion flux across the inner mitochondrial membrane to prevent a wasteful drain on cellular resources, thereby preventing an energetic crisis during stress. Given that F1FO–ATP synthase directly affects mitochondrial membrane potential and having identified the mitochondrial ATP synthase β subunit in a screen for Bcl-xL–binding partners, we tested and found that Bcl-xL failed to protect β subunit–deficient yeast. Thus, by bolstering mitochondrial energetic capacity, Bcl-xL may contribute importantly to cell survival independently of other Bcl-2 family proteins.

Monitoring of mitochondrial membrane potential in isolated perfused rat heart

1984 ◽  
Vol 247 (4) ◽  
pp. H508-H516
Author(s):  
R. A. Kauppinen ◽  
I. E. Hassinen
Keyword(s):  
Membrane Potential ◽  
Mitochondrial Membrane Potential ◽  
Mitochondrial Membrane ◽  
Optical Methods ◽  
Perfused Heart ◽  
Rat Hearts ◽  
Carbonyl Cyanide ◽  
Perfused Rat Hearts ◽  
Beating Rate ◽  
Isolated Perfused Rat Hearts

Optical methods were tested for measuring the membrane potential changes of mitochondria in isolated perfused rat hearts. Safranin was found to be rapidly taken up by the Langendorff-perfused heart, and after loading with the dye there was practically no washout of the stain during perfusion with Krebs-Ringer bicarbonate solution. Staining with safranin induced the appearance of an intense absorption band in the reflectance spectrum of the heart, but the absorbance spectrum changes were not useful for monitoring the mitochondrial membrane potential changes because of interference by endogenous hemoproteins. The fluorescence intensity, however, responded in a manner which indicated that its changes originated from dye attached to the mitochondria. A decrease of the fluorescence was found on energizing the mitochondria by decreasing the cellular energy consumption by arrest induced by 18 mM K+ or by decreasing the beating rate of an electrically paced heart from 5 Hz to the endogenous ventricular frequency of 1.5 Hz. In hearts arrested by Ca2+ depletion, 18 mM K+ did not affect the safranin fluorescence. This was taken to indicate that under these conditions the safranin fluorescence was not sensitive to the plasma membrane potential. The uncoupler carbonyl cyanide m-chlorophenylhydrazone induced an intense enhancement of safranin fluorescence in the perfused heart, demonstrating that the probe is sensitive to mitochondrial membrane potential.(ABSTRACT TRUNCATED AT 250 WORDS)

Protective effect of the dimer of 16,16-diMePGB1 against KCN-induced mitochondrial failure in hepatocytes

1992 ◽  
Vol 263 (2) ◽  
pp. C405-C411 ◽  
Author(s):  
Y. Park ◽  
T. M. Devlin ◽  
D. P. Jones
Keyword(s):  
Membrane Potential ◽  
Protective Effect ◽  
Ion Transport ◽  
Mitochondrial Membrane Potential ◽  
Mitochondrial Function ◽  
Mitochondrial Membrane ◽  
Time Dependent ◽  
Dependent Manner ◽  
Protective Effects ◽  
Cellular Swelling

The dimer and trimer of 16,16-dimethyl-15-dehydroprostaglandin B1 (16,16-diMePGB1) previously have been shown to have protective effects on mitochondrial function. To examine the potential mechanisms involved in protection against mitochondrial failure, we have studied the effects of the dimer of 16,16-diMe-PGB1 (dicalciphor) on mitochondrial function in hepatocytes exposed to KCN. Addition of micromolar concentrations of dicalciphor provided substantial protection against KCN-induced toxicity in a concentration- and time-dependent manner. Dicalciphor, however, had no effect on total or mitochondrial ATP losses in KCN-treated cells. The dimer prevented the marked loss of mitochondrial membrane potential (delta psi) and delta pH that occurs as a result of KCN treatment and prevented KCN-induced loading of phosphate in mitochondria. Furthermore, the dimer of 16,16-diMePGB1 also prevented KCN-induced mitochondrial and cellular swelling. These results demonstrate that dicalciphor protects against KCN-induced damage and that this protection is associated with regulation of specific mitochondrial ion transport functions.

scholarly journals Thrombopoietin Has Protective Effect in Neonatal Hypoxia-Ischemia Rat Model

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 4898-4898
Author(s):  
Liang Li ◽  
Liuming Yang ◽  
Hongwu Xin ◽  
Beng H Chong ◽  
Mo Yang
Keyword(s):  
Membrane Potential ◽  
Protective Effect ◽  
Brain Damage ◽  
Mitochondrial Membrane Potential ◽  
Rat Model ◽  
Mitochondrial Membrane ◽  
Conflicts Of Interest ◽  
Neonatal Rat ◽  
Neural Cells ◽  
Protective Effects

Thrombopoietin (TPO) is a growth factor for the megakaryocytic lineage. The expression of TPO and TPO receptor (c-mpl) in the central nervous system (CNS) and the role of TPO in neural cells and brain damage models were investigated. Our results showed the expression of TPO in human cerebral hemisphere, cerebellum, cerebrospinal fluid and blood plasma. We found that TPO had a protective effect in hypoxic-ischemic rat model, as indicated by the increased ipsilateral brain weight and neuron density in a neonatal rat model of hypoxic-ischemic brain damage. Recoveries of sensorimotor functions and histopathology were observed in these animals that received TPO. In addition, TPO could promote C17.2 cells proliferation by activating PI3K/Akt signaling pathway, and the proliferation could be reduced to nearly basal level by the pre-treatment with LY 294002. The phosphorylation of AKT, which is a hallmark of activation of each molecule was significantly enhanced after the treatment with TPO in the cells, peaking at 30 min after stimulation with TPO. TPO was also found to have an anti-apoptotic effect which mediated via Bcl-2/BAX and suppressing the mitochondrial membrane potential. Results showed the increased level of Bcl-2 and decreased level of BAX were in the time-dependence manner (0, 5, 15, 30 and 60 mins) in these cells. In addition, the mitochondrial membrane potential was significantly decreased by adding 100 ng/ml TPO. Our results indicated that TPO have neural protective effects. Disclosures No relevant conflicts of interest to declare.

Glucosamine-induced alterations of mitochondrial function in pancreatic β-cells: possible role of protein glycosylation

2004 ◽  
Vol 287 (4) ◽  
pp. E602-E608 ◽  
Author(s):  
Marcello Anello ◽  
Daniela Spampinato ◽  
Salvatore Piro ◽  
Francesco Purrello ◽  
Agata Maria Rabuazzo
Keyword(s):  
Membrane Potential ◽  
Mitochondrial Membrane Potential ◽  
Atp Synthase ◽  
Mitochondrial Function ◽  
Chronic Exposure ◽  
Mitochondrial Membrane ◽  
Protein Glycosylation ◽  
Β Cells ◽  
Pancreatic Β Cells ◽  
Protein Levels

Chronic exposure of rat pancreatic islets and INS-1 insulinoma cells to glucosamine (GlcN) produced a reduction of glucose-induced (22.2 mM) insulin release that was associated with a reduction of ATP levels and ATP/ADP ratio compared with control groups. To further evaluate mitochondrial function and ATP metabolism, we then studied uncoupling protein-2 (UCP2), F1-F0-ATP-synthase, and mitochondrial membrane potential, a marker of F1-F0-ATP-synthase activity. UCP2 protein levels were unchanged after chronic exposure to GlcN on both pancreatic islets and INS-1 β-cells. Due to the high number of cells required to measure mitochondrial F1-F0-ATP-synthase protein levels and mitochondrial membrane potential, we used INS-1 cells, and we found that chronic culture with GlcN increased F1-F0-ATP-synthase protein levels but decreased glucose-stimulated changes of mitochondrial membrane potential. Moreover, F1-F0-ATP-synthase was highly glycosylated, as demonstrated by experiments with N-glycosidase F and glycoprotein staining. Tunicamycin (an inhibitor of protein N-glycosylation), when added with GlcN in the culture medium, was able to partially prevent all these negative effects on insulin secretion, adenine nucleotide content, mitochondrial membrane potential, and protein glycosylation. Thus we suggest that GlcN-induced pancreatic β-cell toxicity might be mediated by reduced cell energy production. An excessive protein N-glycosylation of mitochondrial F1-F0-ATP-synthase might lead to cell damage and secretory alterations in pancreatic β-cells.

Mitochondrial Membrane Potential and ATP Production in Primary Disorders of ATP Synthase

2004 ◽  
Vol 14 (1-2) ◽  
pp. 7-11 ◽  
Author(s):  
Alena Vojtíšková ◽  
Pavel Ješina ◽  
Martin Kalous ◽  
Vilma Kaplanová ◽  
Josef Houštěk ◽  
...  
Keyword(s):  
Membrane Potential ◽  
Mitochondrial Membrane Potential ◽  
Atp Synthase ◽  
Mitochondrial Membrane ◽  
Atp Production
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