Temporal changes in cellular energy following burn injury

Area of Science:

• Metabolic responses to injury
• Burn trauma pathophysiology
• Cellular energy metabolism

Background:

• Severe burn injury significantly increases metabolic demands and energy expenditure.
• Adenosine diphosphate (ADP) availability is crucial for regulating cellular respiration.
• Understanding energy deficits post-burn is vital for improving patient outcomes.

Purpose of the Study:

• To investigate the temporal changes in key energy metabolites (ATP, ADP, NAD, NADH) after severe burn injury.
• To assess alterations in hepatic energy status and respiratory control.
• To determine the relationship between burn injury, energy deficit, and phosphorylation limitations.

Main Methods:

• Flame burn model in mice (40% body surface area) under anesthesia.
• Measurement of hepatic surface blood flow and oxygen saturation at multiple time points post-burn.
• Quantification of adenine nucleotides (ATP, ADP, AMP) and pyridine nucleotides (NAD, NADH) in liver biopsies using High-Performance Liquid Chromatography (HPLC).

Main Results:

• Mortality rates of 12.5% at 72 hours and 25% at 1 week post-burn were observed.
• Hepatic oxygen saturation and blood flow remained comparable to control values.
• Significant decreases in ATP, ADP, and energy charge were noted by 72 hours post-burn, indicating impaired energy metabolism despite adequate oxygen supply. NADH levels remained stable.

Conclusions:

• Severe burn injury induces a significant hepatic energy deficit, characterized by reduced ATP and ADP availability.
• The findings support the hypothesis of a limitation in phosphorylation capacity following severe burns.
• Adequate NADH availability suggests that fuel oxidation is not the primary limiting factor for energy production in this context.