ISSN:
1432-2013
Keywords:
Key words Inward rectification
;
Baclofen
;
Barium
;
Caesium
;
Development
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract Biophysical and pharmacological properties, and development of the (–)-baclofen-induced potassium (KBac) conductance and the constitutively active inwardly rectifying potassium (KIR) conductance were characterised using the patch-clamp technique in cultured embryonic rat midbrain neurons. KBac conductance was induced by (–)-baclofen acting on γ-aminobutyric acid B (GABAB) receptors, and displayed a high degree of selectivity for potassium ions, an approximate square-root dependence of conductance on extracellular potassium concentration and strongly voltage-dependent activation. Ba2+ blocked the conductance in a voltage-independent manner, whereas Cs+ produced a voltage-dependent block. In the same preparation, the KIR conductance displayed biophysical properties indistinguishable from those of the KBac conductance. Block of KIR currents by Ba2+ was voltage independent (K I, 4 μM), whereas Cs+ produced a voltage-dependent block (K I, 370 μM at –100 mV, equivalent valence, z′, 1.67). The KBac and KIR conductances additionally displayed a strikingly similar pattern of development in culture; the specific conductance (nS/pF) of both conductances increased two- to three-fold between the first and second week in vitro, and remained constant thereafter.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s004240050247
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