Identification of dysregulation of atrial proteins in rats with chronic obstructive apnea using two-dimensional polyacrylamide gel electrophoresis and mass spectrometry

Obstructive sleep apnea (OSA) affects an estimated 20% of adults worldwide with up to 80% of patients remaining undiagnosed. OSA has been associated with electrical and structural abnormalities of the atria, although the molecular mechanisms are not well understood. We have implemented a rat model of OSA involving the surgical implantation of a tracheal obstructive device. Rats were divided into severe and moderate apnea groups, receiving 23 seconds (severe) or 13 seconds (moderate) apneas per minute, 60 apneas per minute for 8 hours a day over 2 weeks. We recently performed a pilot study using onedimensional polyacrylamide gel electrophoresis (1D PAGE) and nanoliquid chromatography-tandem mass spectrometry (NanoLC-MS/MS) to investigate the protein dysregulations in rat atria which was induced with OSA using the rat model we developed. We found, among others, that some aerobic and anaerobic glycolytic enzymes and Krebs cycle enzymes were downregulated, suggesting that apnea may be a result of paucity of oxygen and production of ATP and reducing equivalents. Here, we used twodimensional polyacrylamide gel electrophoresis (2D PAGE) coupled with nanoLC-MS/MS as a complementary approach to investigate the proteins that are dysregulated in the atria from severe and moderate apnea when compared to control. We not only found that the entire glycolytic pathway and Krebs cycle are downregulated, but also found evidence that additional enzymes involved in the beta-oxidation, electron transport chain and Krebs cycle anaplerotic reactions were also downregulated. Other protein dysregulations identified are involved in metabolic, structural, or inflammatory pathways, suggesting that these proteins may play a role in atrial pathology developing via chronic obstructive apnea and hypoxia.