Mechanical Ventilation Preserves Diaphragm Mitochondrial Function in a Rat Sepsis Model

Abstract Background: To describe the effect of mechanical ventilation on diaphragm mitochondrial oxygen consumption, ATP production, reactive oxygen species (ROS) generation, and cytochrome-c oxidase activity and content, and their relationship to diaphragm strength in an experimental model of sepsis.Methods: A cecal ligation and puncture (CLP) protocol was performed in 12 rats while 12 controls underwent sham-operation. Half of the rats in each group were paralyzed and mechanically ventilated. We performed blood gas analysis and lactic acid assays 6 hours after surgery. Afterwards, we measured diaphragm strength and mitochondrial oxygen consumption, ATP and ROS generation, and cytochrome-c oxidase activity. We also measured malondialdehyde (MDA) content as an index of lipid peroxidation, and mRNA expression of the pro-inflammatory interleukin-1β (IL-1β) in diaphragms.Results: CLP rats showed severe hypotension, metabolic acidosis, and upregulation of diaphragm IL-1β mRNA expression. Compared to sham controls, spontaneously breathing CLP rats showed lower diaphragm force and increased susceptibility to fatigue, along with depressed mitochondrial oxygen consumption and ATP production and cytochrome-c oxidase activity. These rats also showed increased mitochondrial ROS generation and MDA content. Mechanical ventilation markedly restored mitochondrial oxygen consumption and ATP production in CLP rats; lowered mitochondrial ROS production by the complex 3; and preserved cytochrome-c oxidase activity.Conclusion: In an experimental model of sepsis, early initiation of mechanical ventilation restores diaphragm mitochondrial function.

Download Full-text

Mechanical ventilation preserves diaphragm mitochondrial function in a rat sepsis model

Intensive Care Medicine Experimental ◽

10.1186/s40635-021-00384-w ◽

2021 ◽

Vol 9 (1) ◽

Author(s):

P. Eyenga ◽

D. Roussel ◽

B. Rey ◽

P. Ndille ◽

L. Teulier ◽

...

Keyword(s):

Mechanical Ventilation ◽

Oxygen Consumption ◽

Cytochrome C ◽

Cytochrome C Oxidase ◽

Oxidase Activity ◽

Ros Generation ◽

Mitochondrial Oxygen Consumption ◽

Atp Production ◽

Mitochondrial Ros ◽

Mda Content

Abstract Background To describe the effect of mechanical ventilation on diaphragm mitochondrial oxygen consumption, ATP production, reactive oxygen species (ROS) generation, and cytochrome c oxidase activity and content, and their relationship to diaphragm strength in an experimental model of sepsis. Methods A cecal ligation and puncture (CLP) protocol was performed in 12 rats while 12 controls underwent sham operation. Half of the rats in each group were paralyzed and mechanically ventilated. We performed blood gas analysis and lactic acid assays 6 h after surgery. Afterwards, we measured diaphragm strength and mitochondrial oxygen consumption, ATP and ROS generation, and cytochrome c oxidase activity. We also measured malondialdehyde (MDA) content as an index of lipid peroxidation, and mRNA expression of the proinflammatory interleukin-1β (IL-1β) in diaphragms. Results CLP rats showed severe hypotension, metabolic acidosis, and upregulation of diaphragm IL-1β mRNA expression. Compared to sham controls, spontaneously breathing CLP rats showed lower diaphragm force and increased susceptibility to fatigue, along with depressed mitochondrial oxygen consumption and ATP production and cytochrome c oxidase activity. These rats also showed increased mitochondrial ROS generation and MDA content. Mechanical ventilation markedly restored mitochondrial oxygen consumption and ATP production in CLP rats; lowered mitochondrial ROS production by the complex 3; and preserved cytochrome c oxidase activity. Conclusion In an experimental model of sepsis, early initiation of mechanical ventilation restores diaphragm mitochondrial function.

Download Full-text

Cytochrome aa3 in facultatively aerobic and hyperthermophilic archaeon Pyrobaculum oguniense

Canadian Journal of Microbiology ◽

10.1139/w05-040 ◽

2005 ◽

Vol 51 (8) ◽

pp. 621-627 ◽

Cited By ~ 4

Author(s):

Takuro Nunoura ◽

Yoshihiko Sako ◽

Takayoshi Wakagi ◽

Aritsune Uchida

Keyword(s):

Oxygen Consumption ◽

Cytochrome C ◽

Cytochrome C Oxidase ◽

Gene Product ◽

Respiratory Chain ◽

Oxidase Activity ◽

Terminal Oxidase ◽

Hyperthermophilic Archaeon ◽

Consumption Activity ◽

Copper Oxidase

We partially purified and characterized the cytochrome aa3 from the facultatively aerobic and hyperthermophilic archaeon Pyrobaculum oguniense. This cytochrome aa3 showed oxygen consumption activity with N, N, N′, N′-tetramethyl-1,4-phenylenediamine and ascorbate as substrates, and also displayed bovine cytochrome c oxidase activity. These enzymatic activities of cytochrome aa3 were inhibited by cyanide and azide. This cytochrome contained heme As, but not typical heme A. An analysis of trypsin-digested fragments indicated that 1 subunit of this cytochrome was identical to the gene product of subunit I of the SoxM-type heme – copper oxidase (poxC). This is the first report of a terminal oxidase in hyperthermophilic crenarchaeon belonging to the order Thermoproteales.Key words: aerobic respiratory chain, terminal oxidase, Archaea, hyperthermophile, Pyrobaculum.

Download Full-text

Sulphide oxidation and oxidative phosphorylation in the mitochondria of the lugworm

Journal of Experimental Biology ◽

10.1242/jeb.200.1.83 ◽

1997 ◽

Vol 200 (1) ◽

pp. 83-92 ◽

Cited By ~ 3

Author(s):

S Vökel ◽

M K Grieshaber

Keyword(s):

Oxygen Consumption ◽

Cytochrome C ◽

Oxidative Phosphorylation ◽

Cytochrome C Oxidase ◽

Electron Flow ◽

Respiratory Control ◽

Sulphide Oxidation ◽

Atp Production ◽

Sulphide Concentration ◽

Flow Through

Oxygen consumption, ATP production and cytochrome c oxidase activity of isolated mitochondria from body-wall tissue of Arenicola marina were measured as a function of sulphide concentration, and the effect of inhibitors of the respiratory complexes on these processes was determined. Concentrations of sulphide between 6 and 9 µmol l-1 induced oxygen consumption with a respiratory control ratio of 1.7. Production of ATP was stimulated by the addition of sulphide, reaching a maximal value of 67 nmol min-1 mg-1 protein at a sulphide concentration of 8 µmol l-1. Under these conditions, 1 mole of ATP was formed per mole of sulphide consumed. Higher concentrations of sulphide led to a decrease in ATP production until complete inhibition occurred at approximately 50 µmol l-1. The production of ATP with malate and succinate was stimulated by approximately 15 % in the presence of 4 µmol l-1 sulphide, but decreased at sulphide concentrations higher than 1520 µmol l-1. Cytochrome c oxidase was also inhibited by sulphide, showing half-maximal inhibition at 1.5 µmol l-1 sulphide. Sulphide-induced ATP production was inhibited by antimycin, cyanide and oligomycin but not by rotenone or salicylhydroxamic acid. The present data indicate that sulphide oxidation is coupled to oxidative phosphorylation solely by electron flow through cytochrome c oxidase, whereas the alternative oxidase does not serve as a coupling site. At sulphide concentrations higher than 20 µmol l-1, oxidation of sulphide serves mainly as a detoxification process rather than as a source of energy.

Download Full-text