Protein kinase C activators reduce the inositol trisphosphate-induced outward current and the Ca2+-activated outward current in identified neurons of Aplysia.
Effects of intracellularly injected activators of protein kinase C on the InsP3-induced K+ current and the Ca2+-activated K+ current recorded from identified neurons (R9-R12) of Aplysia kurodai were investigated with conventional voltage-clamp and pressure-injection techniques. Intracellular injection of InsP3 into identified neurons produced a 4-aminopiridine (4-AP)-resistant, tetraethylammonium (TEA)-sensitive, and quinidine-sensitive K+ current similar to the Ca2+ activated K+ current elicited by direct injection of Ca2+ ions into the same neurons. The diacylglycerol analogue 1,2-oleoylacetylglycerol (OAG) at an intracellular concentration of 65 nM produced irreversible decreases in both the InsP3-induced K+ current and the Ca2+-activated K+ current. The phorbol 12,13-dibutyrate (PDBu) at an intracellular concentration of 150 nM also decreased irreversibly both the InsP3-induced K+ current and the Ca2+-activated K+ current. These results suggest that protein kinase C activators reduce both the InsP3-induced K+ current and the Ca2+-activated K+ current recorded from certain identified neurons of Aplysia and that protein kinase C reduces the ability of Ca2+ to open K+ channels rather than affecting the ability of InsP3 to release Ca2+ from intracellular stores.
Sawada
M
M
Department of Physiology, Shimane Medical University, Izumo, Japan.
Ichinose
M
M
Maeno
T
T
D015761:4-Aminopyridine; D000631:Aminopyridines / Q000494:pharmacology*; D000818:Animals; D001048:Aplysia; D002118:Calcium / Q000494:pharmacology*; D004075:Diglycerides / Q000494:pharmacology; D004553:Electric Conductivity; D005724:Ganglia / Q000502:physiology; D066298:In Vitro Techniques; D015544:Inositol 1,4,5-Trisphosphate; D007295:Inositol Phosphates / Q000502:physiology*; D007700:Kinetics; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D015240:Phorbol 12,13-Dibutyrate / Q000494:pharmacology; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology*; D011493:Protein Kinase C / Q000378:metabolism*; D015290:Second Messenger Systems; D013403:Sugar Phosphates / Q000502:physiology*; D019789:Tetraethylammonium; D013757:Tetraethylammonium Compounds / Q000494:pharmacology*
D000631:Aminopyridines; D004075:Diglycerides; D007295:Inositol Phosphates; D015221:Potassium Channels; D013403:Sugar Phosphates; D013757:Tetraethylammonium Compounds; D015240:Phorbol 12,13-Dibutyrate; D019789:Tetraethylammonium; D015544:Inositol 1,4,5-Trisphosphate; C038237:1-oleoyl-2-acetylglycerol; D015761:4-Aminopyridine; D011493:Protein Kinase C; D002118:Calcium