Selective downregulation of an inactivating K+ conductance by analogues of cAMP in mouse Schwann cells

• Published in: The Journal of physiology Vol. 499; no. Pt 3; pp. 655 - 660
• Main Authors: Despeyroux, S, Beaudu-Lange, C, Coles, J A, Amedee, T
• Format: Journal Article
• Language: English
• Published: England The Physiological Society 15-03-1997
• Subjects: 8-Bromo Cyclic Adenosine Monophosphate - pharmacology; Animals; Cyclic AMP - analogs & derivatives; Cyclic AMP - pharmacology; Cyclic AMP - physiology; Cyclic AMP-Dependent Protein Kinases - antagonists & inhibitors; Cyclic GMP - analogs & derivatives; Cyclic GMP - pharmacology; Down-Regulation; Enzyme Inhibitors - pharmacology; Ganglia, Spinal - drug effects; Ganglia, Spinal - embryology; Mice; Potassium Channels - drug effects; Potassium Channels - physiology; Schwann Cells - drug effects; Schwann Cells - physiology; Structure-Activity Relationship; Thionucleotides - pharmacology
• ISSN: 0022-3751; 1469-7793
• DOI: 10.1113/jphysiol.1997.sp021958

1. Voltage-dependent K+ conductances on Schwann cells in organotypic cultures of mouse dorsal root ganglia were classified
as inactivating or sustained (responsible for currents IA and IK, respectively). IA is known to be much reduced on Schwann
cells that contact neurites. 2. In the absence of neurones, IA and IK were present. IA, but not IK, was markedly reduced (by
80% after 105 h of treatment) by 2 mM 8-(4-chlorophenylthio)-cAMP (cpt-cAMP), a weakly hydrolysable analogue of cAMP. The
effect did not appear for at least 2 h and was maximal after about 100 h. 3. The effect of 1 mM cpt-cAMP was abolished in
the presence of an inhibitor of protein kinases, N-[2-bromocinnamyl(amino)ethyl]-5-isoquinolinesulphonamide (H-89, 10 microM).
4. Other analogues of cAMP, but not an analogue of cGMP (8-bromo-cGMP), also reduced IA. 5. We conclude that IA, but not IK,
can be downregulated by activation of the protein kinase A pathway.