Hypoxia induces glucose transporter expression in endothelial cells

Area of Science:

• Cell Biology
• Metabolic Biochemistry
• Physiology

Background:

• Endothelial cells are frequently exposed to hypoxic conditions in various tissues.
• Understanding endothelial cell energy metabolism under hypoxia is crucial for physiological and pathological contexts.

Purpose of the Study:

• To investigate the effects of sustained hypoxia on energy metabolism in endothelial cells.
• To elucidate the mechanisms of metabolic adaptation in endothelial cells under low oxygen.

Main Methods:

• Cultured bovine aortic and human umbilical vein endothelial cells under sustained hypoxic conditions (14 mmHg) for up to 96 hours.
• Assessed glucose transport activity, glucose consumption, and lactic acid production.
• Analyzed mRNA and protein expression of glucose transporters.
• Investigated effects of oxidative phosphorylation inhibitors/uncouplers on normoxic cells.

Main Results:

• Hypoxic endothelial cells showed upregulated glucose transport activity, increased glucose consumption, and elevated lactic acid production compared to normoxic cells.
• Upregulation of glucose transporter expression (erythroid/brain form) occurred over several hours and was linked to hypoxia.
• Inhibition of oxidative phosphorylation under normoxia also led to increased glucose transporter expression.
• Endothelial cells were found to contain phosphocreatine and express both brain and muscle creatine kinase isozymes.

Conclusions:

• Reduced rates of oxidative metabolism may signal endothelial cells to adapt metabolically to hypoxic environments.
• Endothelial cells possess a creatine kinase system, indicating a role in energy buffering.
• Sustained hypoxia induces significant metabolic shifts in endothelial cells, primarily towards glycolysis.