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Two distinct inwardly rectifying conductances are expressed in long term dibutyryl‐cyclic‐AMP treated rat cultured cortical astrocytes
Author(s) -
Ferroni Stefano,
Marchini Cristina,
Schubert Peter,
Rapisarda Carmela
Publication year - 1995
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(95)00588-z
Subject(s) - chemistry , biophysics , cortical neurons , astrocyte , neuroscience , term (time) , microbiology and biotechnology , medicine , biology , central nervous system , physics , quantum mechanics
Long term incubation (1–3 weeks) with 250 μM dibutyryl‐cyclic‐AMP (dBcAMP) of pure cultured cortical astrocytes from newborn rats leads to the expression of voltage‐dependent, inward‐rectifying potassium (K + ) and chloride (Cl − ) currents which are lacking in shortly treated (4–24 h) and in control cultured astrocytes. Both conductances are already activated at the holding potential of −60 mV and are distinguishable for their gating kinetics and pharmacological sensitivity. K + currents have a fast activation kinetic and show a time‐ and voltage‐dependent inactivation at potentials negative to −120 mV. The conductive property of the K + currents increases upon elevation of the extracellular K + concentration ([K + ] 0 ) and they are reversibly blocked by extracellular 0.1 mM barium ions (Ba 2+ ). Cl − currents are activated only at negative membrane potentials; they display a slow activation kinetic, no time‐dependent inactivation and are not affected by 0.1 mM Ba 2+ . In individual astrocyte the K + and Cl − conductances can be expressed singularly or in combination. The results indicate that the expression of these two conductances is controlled by a cAMP‐dependent molecular signalling, presumably by regulating a late gene activation. Thus, the strengthening of this signalling would contribute to promote the maturation of less differentiated astrocytes in culture, implicating the expression of K + and Cl − membrane conductances which may operate together in the regulation of [K + ] 0 homeostasis via the mechanism of the local accumulation.