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Low glucose‐induced mitochondrial dysfunction enhances hypoxia‐reoxygenation injury in brain microvascular endothelial cells (1079.4)
Author(s) -
Katakam Prasad,
Liu Dan,
Gordon Angellica,
Dutta Somhrita,
Sure Venkata,
Rutkai Ibolya,
Busija David
Publication year - 2014
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.28.1_supplement.1079.4
Subject(s) - enos , endocrinology , medicine , hypoxia (environmental) , reactive oxygen species , viability assay , chemistry , mitochondrion , insulin , nitric oxide , endothelial nos , endothelial dysfunction , nitric oxide synthase , apoptosis , biology , oxygen , biochemistry , organic chemistry
Our previous studies have shown that hypoxia‐reoxygenation (H‐R) uncouples endothelial nitric oxide synthase (eNOS) promoting reactive oxygen species (ROS)‐induced ROS formation (RIR) from mitochondria and increased cell death. Thus, we hypothesized that low glucose levels promote mitochondrial dysfunction and RIR involving NOS uncoupling leading to a paradoxically enhanced cellular injury to insulin. Primary rat brain microvascular endothelial cells (MECs) and human MECs were treated with low (5 mmol/L, LG) or normal glucose (25 mmol/L, NG) media in the presence and absence of L‐NAME (100µM, eNOS inhibitor) or insulin (100 ng/ml) and exposed to 2 hr hypoxia (~1% O 2 ) followed by 1 hr reoxygenation. Insulin and L‐NAME increased cell viability following H‐R in NG (22±7% and 25±2%, p<0.05) but paradoxically diminished cell viability in LG (‐16±4% and ‐17±4%). In MECs, H‐R‐induced eNOS uncoupling (increased monomer/dimer ratio) was diminished by insulin and L‐NAME in NG but paradoxically enhanced in LG. Measurements of oxygen consumption rate in human MECs showed that LG reduced mitochondrial respiratory capacity. L‐NAME diminished mitochondrial capacity of MECs when treated with NG but not LG. Thus, LG promoted mitochondrial dysfunction leading to eNOS uncoupling and impaired NO signaling transforming insulin from a cytoprotective to a cytolethal hormone.Grant Funding Source : Supported by NIH grant numbers HL‐077731, HL‐030260, HL093554, and HL‐065380 (Busija)