Two distinct inwardly rectifying conductances are expressed in long term dibutyryl‐cyclic‐AMP treated rat cultured cortical astrocytes

FEBS Letters

Marchini, Cristina¹  Rapisarda, Carmela¹  Schubert, Peter²  Ferroni, Stefano¹ 

[1] Department of Human and General Physiology, University of Bologna, Via San Donato 19/2, 40127 Bologna, Italy;Max-Planck Institute for Psychiatry, Department of Neuromorphology, Martinsried, Germany

关键词: Rat cortical astrocyte;    Cyclic-AMP analog;    Inward-rectifying current;    K+ channel;    Cl− channel;    Gene expression regulation;   

DOI  :  10.1016/0014-5793(95)00588-Z

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

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 (Ba²⁺). 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 Ba²⁺. 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.

【 授权许可】

Unknown