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+ cur rent in cultured colliculi neurons. The aim of the present study was to cha racterize the channel responsible for this cAMP-dependent effect. We detect ed the presence of a non-inactivating voltage-dependent 16-pS K+ channel th at displayed long-lasting inhibition upon a brief application of cAMP and g reater sensitivity to tetraethylammonium than to 4-aminopyridine. In additi on 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. The se results suggest the presence of common sustained cAMP-dependent processe s responsible for both up- and down-regulation of these channels in the neu rons studied. They indicate that the 16-pS, but not the 8-pS or the 49-pS c hannels, participates in the cAMP-inhibited macroscopic K+ current.