Oxygen dynamics during in vitro seizures
© Wei et al; licensee BioMed Central Ltd. 2012
Published: 16 July 2012
Oxygen is an essential element for brain activity. The brain is a metabolic engine that requires 20% of the body’s metabolic energy, despite being only 2% of the human body mass . Two thirds of brain’s metabolic energy is dedicated to supporting neural spiking activity. Much of the O2 dependent ATP metabolism in single neurons is used by energetic Na/K-ATPase pumps that transport 3Na+ outwards with 2K+ inward against their concentration gradients for each ATP hydrolyzed [2, 3]. However, understanding the relationship between seizures and real-time oxygen dynamics has been restricted by current technical limitations. Computational models can offer insight to help understand the measurements from experiments.
We have performed experiments relating seizure activity at the cellular level with simultaneous real-time O2 microdomain measurements. In this paper, we build a mathematical neuron model that extends the Hodgkin-Huxley formalism containing leak currents for sodium, potassium and chloride ions, transient sodium currents, and delayed rectifier potassium currents. This neuron was embedded within an extracellular space and a simplified glia-endothelium system. The Na+ and K+ ion concentrations as well as extracellular oxygen density were continuously estimated. Hypoxia was modeled by reducing both neuron and glial Na/K-ATPase pump activities.
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