title: Electrophysiological and morphological characterization of dentate astrocytes in the hippocampus.
abstract: We studied electrophysiological and morphological properties of astrocytes in the dentate gyrus of the rat hippocampus in slices. Intracellular application of Lucifer yellow revealed two types of morphology: one with a long process extruding from the cell body, and the other with numerous short processes surrounding the cell body. Their electrophysiological properties were either passive, that is, no detectable voltage-dependent conductance, or complex, with Na+/K+ currents similar to those reported in the Ammon's horn astrocytes. We did not find any morphological correlate to the types of electrophysiological profile or dye coupling. Chelation of cytoplasmic calcium ([Ca2+]i) by BAPTA increased the incidence of detecting a low Na+) conductance and transient outward K+ currents. However, an inwardly rectifying K+ current (Kir), a hallmark of differentiated CA1/3 astrocytes, was not a representative K+-current in the complex dentate astrocytes, suggesting that these astrocytes could retain an immature form of K-currents. Dentate astrocytes may possess a distinct current profile that is different from those in CA1/3 Ammon's horn.
authors.affiliation: Department of Physiology, University of Maryland, 655 W. Baltimore Street, Baltimore, Maryland 21201, USA. misok001@yahoo.com
authors.forename: Masako
authors.initials: M
authors.lastname: Isokawa
authors.forename: Guy M
authors.initials: GM
authors.lastname: McKhann
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000166:cytology* / Q000502:physiology*; D002118:Calcium / Q000378:metabolism; D048430:Cell Shape; D003600:Cytosol / Q000502:physiology; D018891:Dentate Gyrus / Q000166:cytology* / Q000502:physiology*; D004594:Electrophysiology; D008297:Male; D008564:Membrane Potentials / Q000502:physiology; D009924:Organ Culture Techniques; D024661:Potassium Channels, Inwardly Rectifying / Q000502:physiology; D017966:Pyramidal Cells / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012964:Sodium / Q000378:metabolism; D015222:Sodium Channels / Q000502:physiology
chemical_list: D024661:Potassium Channels, Inwardly Rectifying; D015222:Sodium Channels; D012964:Sodium; D002118:Calcium