title: Expression of potassium channels during postnatal differentiation of rabbit Müller glial cells.
abstract: The postnatal maturation of Müller glial cells from immature radial glial cells is accompanied by specific changes in the activity of distinct types of K+ channels, as shown by whole-cell and cell-attached records on freshly isolated cells from retinae of young (postnatal days 1-30, P1-P30) and adult rabbits. (i) The density of inwardly rectifying currents, providing the main K+ conductance in adult Müller cells, was very low (0.8 pA/pF) from P1 to P6 but increased rapidly thereafter until a relatively stable level of 11.0 pA/pF was established at P17. (ii) Transient (A-type) K+ currents were expressed in all immature cells at a high density (9.6 pA/pF). After P12, both the percentage of cells with A-type currents and the peak amplitudes of the currents (2.8 pA/pF) declined. (iii) Delayed rectifying K+ currents developed slowly until after P30. (iv) The postnatal maturation of radial glial cells was accompanied by a strong decrease in the activity of large-conductance, Ca2+-activated K+ channels, the open probability of which (measured at the resting membrane potential) decreased from 0.69 at P2-4 to 0.06 at P13-14. The developmental decrease of the activity of Ca2+-activated K+ channels is assumed to be mainly caused by alteration of the resting membrane potential which developed from low values (-49 mV) at P1-6 to high adult values (-84 mV) after P13. The activity of each distinct type of K+ channel investigated is differently modulated by developmental regulation. This may reflect different functional requirements of immature and mature Müller cells.
authors.affiliation: Paul Flechsig Institute of Brain Research, Department of Neurophysiology, University of Leipzig, Germany. bria@serrver3.medizin.uni-leipzig.de
authors.forename: A
authors.initials: A
authors.lastname: Bringmann
authors.forename: B
authors.initials: B
authors.lastname: Biedermann
authors.forename: A
authors.initials: A
authors.lastname: Reichenbach
mesh_terms: D000818:Animals; D000831:Animals, Newborn / Q000378:metabolism* / Q000502:physiology; D001920:Bradykinin / Q000378:metabolism; D002118:Calcium / Q000502:physiology; D002454:Cell Differentiation / Q000502:physiology; D004553:Electric Conductivity; D007473:Ion Channels / Q000502:physiology; D008564:Membrane Potentials / Q000502:physiology; D009457:Neuroglia / Q000166:cytology* / Q000378:metabolism* / Q000502:physiology; D015221:Potassium Channels / Q000378:metabolism* / Q000502:physiology; D011817:Rabbits; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism
chemical_list: D007473:Ion Channels; D015221:Potassium Channels; D001920:Bradykinin; D002118:Calcium