title: Potassium currents in primary cultured astrocytes from the rat corpus callosum.
abstract: The corpus callosum (CC) is the main white matter tract in the brain and is involved in interhemispheric communication. Using the whole-cell voltage-clamp technique, a study was made of K(+)-currents in primary cultured astrocytes from the CC of newborn rats. These cells were positive to glial fibrillary acidic protein after culturing in Dulbecco's Modified Eagle Medium (> 95% of cells) or in serum-free neurobasal medium with G5 supplement (> 99% of cells). Astrocytes cultured in either medium displayed similar voltage-activated ion currents. In 81% of astrocytes, the current had a transient component and a sustained component, which were blocked by 4-aminopyridine and tetraethylammonium, respectively; and both had a reversal potential of -66 mV, indicating that they were carried by K(+) ions. Based on the Ba(2+)-sensitivity and activation kinetics of the K(+)-current, two groups of astrocytes were discerned. One group (55% of cells) displayed a strong Ba(2+) blockade of the K(+)-current whose activation kinetics, time course of decay, and the current-voltage relationship were modified by Ba(2+). This current was greatly blocked (52%) by Ba(2+) in a voltage-dependent way. Another group (45% of cells) presented weak Ba(2+)-blockade, which was only blocked 24% by Ba(2+). The activation kinetics and time course of decay of this current component were unaffected by Ba(2+). These results may help to understand better the roles of voltage-activated K(+)-currents in astrocytes from the rat CC in particular and glial cells in general.
authors.affiliation: Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Querétaro, 76230, México.
authors.forename: Daniel
authors.initials: D
authors.lastname: Reyes-Haro
authors.forename: Ricardo
authors.initials: R
authors.lastname: Miledi
authors.forename: Jesús
authors.initials: J
authors.lastname: García-Colunga
mesh_terms: D015761:4-Aminopyridine / Q000494:pharmacology; D000818:Animals; D001253:Astrocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D001464:Barium / Q000494:pharmacology; D015415:Biomarkers; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D048430:Cell Shape / Q000502:physiology; D002478:Cells, Cultured; D003337:Corpus Callosum / Q000166:cytology / Q000378:metabolism*; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009413:Nerve Fibers, Myelinated / Q000378:metabolism* / Q000648:ultrastructure; D018408:Patch-Clamp Techniques; D011188:Potassium / Q000378:metabolism*; D026902:Potassium Channel Blockers / Q000494:pharmacology; D024642:Potassium Channels, Voltage-Gated / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D019789:Tetraethylammonium / Q000494:pharmacology
chemical_list: D015415:Biomarkers; D005904:Glial Fibrillary Acidic Protein; D026902:Potassium Channel Blockers; D024642:Potassium Channels, Voltage-Gated; D001464:Barium; D019789:Tetraethylammonium; D015761:4-Aminopyridine; D011188:Potassium