Heerlein 2005 Am J Respir Cell Mol Biol

Heerlein K, Schulze A, Hotz L, Bartsch P, Mairbäurl H (2005) Hypoxia decreases cellular ATP demand and inhibits mitochondrial respiration of a549 cells. Am J Respir Cell Mol Biol 32:44-51.

» PMID: 15388515

Heerlein K, Schulze A, Hotz L, Bartsch P, Mairbaeurl H (2005) Am J Respir Cell Mol Biol

Abstract: Hypoxia inhibits activity and expression of transporters involved in alveolar Na reabsorption and fluid clearance. We studied whether this represents a mechanism for reducing energy consumption or whether it is the consequence of metabolic dysfunction. Oxygen consumption (JO₂) of A549 cells and primary rat alveolar type II cells was measured by microrespirometry during normoxia, hypoxia (1.5% O₂), and reoxygenation. In both cell types, acute and 24-h hypoxia decreased total JO₂ significantly and reoxygenation restored JO₂ after 5 min but not after 24 h of hypoxia in A549 cells, whereas recovery was complete in type II cells. In A549 cells under normoxia Na/K-ATPase accounted for ~ 15% of JO₂, whereas Na/K-ATPase–related JO₂ was decreased by ~ 25% in hypoxia. Inhibition of other ion transporters did not affect JO₂. Protein synthesis–related JO₂ was not affected by acute hypoxia, but decreased by 30% after 24-h hypoxia. Acute and 24-h hypoxia decreased JO₂ of A549 cell mitochondrial complexes I, II, and III by 30–40%. Reoxygenation restored complex I activity after acute hypoxia but not after 24-h hypoxia. ATP was decreased 30% after 24-h hypoxia, but lactate production rate was not affected. Reduced nicotinamine adenine dinucleotide was slightly elevated in acute hypoxia. Our findings indicate that inhibition of the Na/K-ATPase by hypoxia contributes little to energy preservation in hypoxia. It remains unclear to what extent hypoxic inhibition of mitochondrial metabolism affects ATP-consuming processes. • Keywords: Energy metabolism, Hypoxia, Mitochondrial electron transfer chain, Na-transport, respirometry

• O2k-Network Lab: DE Heidelberg Mairbaeurl H

Labels: MiParea: Respiration 

Organism: Rat  Tissue;cell: Endothelial;epithelial;mesothelial cell, Blood cells, Other cell lines  Preparation: Intact cells 

Regulation: Ion;substrate transport, Oxygen kinetics 

HRR: Oxygraph-2k