Hippocampal slice (K+)e: depth profiles and changes induced by stimulation or anoxia

Area of Science:

• Neuroscience
• Physiology
• Biomedical Engineering

Background:

• Assessing the functional state of explanted brain tissue is crucial for research.
• Developing reliable methods for early functional assessment is needed.

Purpose of the Study:

• To develop a technique for early assessment of the functional state of explanted rat hippocampal slices.
• To measure extracellular potassium ((K+)e) in CA1 region of rat hippocampal slices.

Main Methods:

• Utilized K+-selective microelectrodes to measure (K+)e in rat hippocampal slices.
• Compared (K+)e profiles in slices maintained at the medium-gas interface versus submersed slices.
• Investigated the effects of electrical stimulation and anoxic episodes on (K+)e.

Main Results:

• Exposed slices showed high surface (K+)e that remained elevated, while submersed slices exhibited a more uniform (K+)e profile.
• In submersed slices, a decrease in central (K+)e to 6 mmol/l over 2 hours indicated viability.
• Electrical stimulation and anoxia induced characteristic (K+)e changes in viable slices.

Conclusions:

• Submersed hippocampal slices offer a more uniform (K+)e profile compared to exposed slices.
• Early detection of low (K+)e levels in submersed slices is a reliable predictor of tissue viability.
• This technique allows for early assessment of the functional state of explanted brain tissue.