Mechanical Ventilation Preserves Diaphragm Mitochondrial Function in a Rat Sepsis Model
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.
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Due to technical limitations, table1 and table2 are only available as a download in the Supplemental Files section.
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Table 1: Arterial blood gases (pH, PaO2, PaCO2, HCO3-) and plasma lactic acid measured at the end of the procedure in control, sepsis, MV-sepsis and MV-control groups. Data are means ±SEM from 6 animals per group. Data are means ±SEM from 6 animals per group. * p<0.05 sepsis versus control; † p<0.05 sepsis versus MV-control; ‡ p < 0.05 MV-sepsis versus control and § p<0.05 MV-sepsis versus MV control
Table 2. Mitochondrial oxygen consumption and ATP synthesis Measures were performed on diaphragm mitochondria from rats of the four following groups: spontaneously breathing controls (Control), spontaneously breathing sepsis group (Sepsis), mechanically ventilated control group (MV-Control) and a mechanically ventilated sepsis group (MV-Sepsis). Mitochondria were energized with succinate as respiratory substrate in the presence of rotenone State 3 phosphorylating respiration as well as ATP production were measured at 100 µM of exogenous ADP. State 4 respiration was obtained by inhibiting the ATP synthase with 3µg/ml of oligomycin.. Data are means ±SEM from 6 animals per group. * p<0.05 sepsis versus Control; † p<0.05 sepsis versus MV-Control; £ p<0.05 sepsis versus MV-sepsis.
Posted 22 Oct, 2020
On 19 Jan, 2021
Received 19 Jan, 2021
On 19 Jan, 2021
Received 16 Jan, 2021
On 26 Dec, 2020
Invitations sent on 01 Nov, 2020
On 23 Oct, 2020
On 22 Oct, 2020
On 19 Oct, 2020
On 18 Oct, 2020
Mechanical Ventilation Preserves Diaphragm Mitochondrial Function in a Rat Sepsis Model
Posted 22 Oct, 2020
On 19 Jan, 2021
Received 19 Jan, 2021
On 19 Jan, 2021
Received 16 Jan, 2021
On 26 Dec, 2020
Invitations sent on 01 Nov, 2020
On 23 Oct, 2020
On 22 Oct, 2020
On 19 Oct, 2020
On 18 Oct, 2020
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.
Figure 1
Figure 2
Figure 3
Figure 4
Due to technical limitations, table1 and table2 are only available as a download in the Supplemental Files section.