NSF Award
0136960
LAY SUMMARY; ION CHANNELS in HIPPOCAMPAL ASTROCYTES. Harold K. Kimelberg and Min Zhou <br/><br/> Voltage gated ion channels for the small cations sodium (Na+ ) and potassium (K+ ) are responsible for the wave of depolarization that travels down the neuronal axon and excites other neurons to which it is linked by synapses, where the depolarization releases neurotransmitters which rapidly diffuse across the synaptic cleft to stimulate the next neuron, and so on,. The formation of circuits by such connected neurons are thought to underlie how the brain works. The properties of the Na+ and K+ ion channels in neurons have been extensively studied. The other major type of brain cells are called glia and they are not excitable. Current studies have now shown that these cells can contain the same type of voltage sensitive sodium and potassium channels as are found in neurons, and also voltage dependant chloride channels. This is surprising as the function of these channels is thought to be to modulate neuronal excitability and the glia are unexcitable. <br/>This project will use a freshly isolated preparation of one of the main kinds of glial cells the astroglia to identify what ion channels are present in these cells and to help understand their functions. Our work to date shows that this preparation can be divided into two different classes of astroglia based on a different repertoire of channels. Knowledge of the detailed properties of these channels will give us important clues as to their functions. We will test one hypothesis that one type of astrocyte but not the other has K+ channels and Cl- channels designed to allow it take up K+ plus Cl- when K+ is released via the outward rectifying K+ channel on neurons during impulse conduction. (293 words).
