cAMP-mediated long-term modulation of voltage-dependent K+ channels in cultured colliculi neurons.
Previously, we have described prolonged cAMP-induced inhibition of a K+ current in cultured colliculi neurons. The aim of the present study was to characterize the channel responsible for this cAMP-dependent effect. We detected the presence of a non-inactivating voltage-dependent 16-pS K+ channel that displayed long-lasting inhibition upon a brief application of cAMP and greater sensitivity to tetraethylammonium than to 4-aminopyridine. In addition to this channel, colliculi neurons express two other voltage-sensitive, non-inactivating K+ channels (8 and 49 pS) whose activity is facilitated by a brief application of cAMP, the effect of which is also long-lasting. These results suggest the presence of common sustained cAMP-dependent processes responsible for both up- and down-regulation of these channels in the neurons studied. They indicate that the 16-pS, but not the 8-pS or the 49-pS channels, participates in the cAMP-inhibited macroscopic K+ current.
Milhaud
D
D
CNRS UPR 9023, C.C.I.P.E., 141 rue de la Cardonille, F-34094 Montpellier Cedex 5, France.
Michel
J M
JM
Bockaert
J
J
Fagni
L
L
D015761:4-Aminopyridine / Q000494:pharmacology; D000818:Animals; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000494:pharmacology*; D004553:Electric Conductivity; D004622:Embryo, Mammalian; D008564:Membrane Potentials; D051379:Mice; D009474:Neurons / Q000502:physiology*; D018408:Patch-Clamp Techniques; D026902:Potassium Channel Blockers; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology*; D003336:Tectum Mesencephali / Q000502:physiology*; D019789:Tetraethylammonium / Q000494:pharmacology
D026902:Potassium Channel Blockers; D015221:Potassium Channels; D019789:Tetraethylammonium; D015761:4-Aminopyridine; D000242:Cyclic AMP