Bench-to-bedside review: lactate and the lung

Area of Science:

• Pulmonary Medicine
• Cellular Metabolism
• Critical Care

Background:

• Isolated lung tissue exhibits glucose uptake and lactate release, similar to other tissues.
• In vivo studies in healthy humans show no detectable lung lactate production.
• Lactate production by the lung may be a significant indicator in disease states.

Purpose of the Study:

• To investigate the potential for lung lactate production in various physiological and pathological conditions.
• To explore the mechanisms underlying lactate production in injured lung tissue.
• To understand the lung's contribution to systemic metabolic responses during severe illness.

Main Methods:

• In vivo assessment of lung lactate exchange in normal human subjects.
• Analysis of potential mechanisms for lactate production in injured lungs, including hypoxia and cytokine effects.
• Examination of metabolic adaptations in lung tissue in response to systemic mediators.

Main Results:

• No measurable lactate production was detected in the lungs of normal human subjects in vivo.
• Potential mechanisms for lactate production in injured lungs include anaerobic metabolism, cytokine influence, and accelerated glucose metabolism in parenchymal and inflammatory cells.
• Lung tissue may exhibit metabolic adaptations and contribute to systemic responses in severe illness.

Conclusions:

• While healthy lungs do not measurably produce lactate, injured lungs may do so through several mechanisms.
• Lung lactate production can be a marker for conditions like acute lung injury and acute respiratory distress syndrome.
• The lung can adapt metabolically and contribute to systemic responses during critical illness.