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Ischemic brain slice glucose utilization: effects of slice thickness, acidosis, and K+
G C Newman1, F E Hospod, S L Schissel
1Neurology Service, Veterans Administration Medical Center, Northport, New York.
Summary
Brain slice thickness impacts metabolic product retention during ischemia. Acidosis inhibits glucose phosphorylation, while increased extracellular potassium stimulates glucose utilization and lactate accumulation.
Area of Science:
- Neuroscience
- Biochemistry
- Cell Biology
Background:
- Ischemia disrupts brain metabolism, affecting energy production and waste product accumulation.
- Brain slice models are crucial for studying cellular responses to ischemic conditions in vitro.
Purpose of the Study:
- To investigate how varying brain slice thickness influences metabolic product retention in an in vitro ischemia model.
- To examine the effects of extracellular potassium (K+) levels and pH on glucose utilization and lactate content in brain slices of different thicknesses.
Main Methods:
- Utilized brain slices of 540-, 660-, and 1,000-microns thickness in an in vitro ischemia model.
- Measured glucose utilization and lactate content in buffers with varied extracellular K+ levels and pH.
- Analyzed 2-deoxyglucose metabolites to understand glucose metabolism pathways.
Main Results:
- Increased anaerobic glycolysis and lactate accumulation were observed in thicker slices (660-1,000 microns).
- Acidosis (low pH) suppressed glucose utilization by inhibiting glucose phosphorylation, but did not affect tissue lactate levels.
- Increased extracellular K+ stimulated glucose utilization and lactate production across all tested slice thicknesses.
Conclusions:
- Brain slice thickness is a critical factor in the retention of metabolic products during ischemia.
- Acidosis impairs glucose metabolism through phosphorylation inhibition, with potential for cellular injury due to persistent glycolysis.
- Elevated extracellular K+ may have a dual role in brain tissue metabolism, stimulating glucose utilization and influencing metabolic product removal.