EPYLRFamide-mediated reduction of acetylcholine-induced inward currents in Helix lucorum-identified neurones: role of NAADP-dependent and IP3-dependent Ca2+ release from internal stores, calmodulin and Ca2+/calmodulin-dependent protein kinase II.
The effect of seven compounds intracellularly applied by spontaneous diffusion were investigated on the EPYLRFamide-induced reduction of acetylcholine-induced inward current (ACh-current) recorded from identified neurones from Helix lucorum. Inward currents were recorded from neurones LPa2, LPa3, RPa3 and RPa2 in isolated ganglia preparations using two-electrode voltage clamp technique. ACh was applied ionophoretically. Heparin, an antagonist of IP(3) receptors (IP(3)Rs), and IP(3), the agonist of IP(3)Rs, decreased the effect of EPYLRFamide. Thio-NADP, a blocker of NAADP-induced Ca(2+) release, beta-NAADP, Ca(2+) releaser, R24571, W-7 (both calmodulin antagonists), and KN-62, a selective inhibitor of Ca(2+)/calmodulin-dependent protein kinase II, did not change the modulatory effect of EPYLRFamide. These data suggest that EPYLRFamide decreases ACh-current through elevation of the basal intracellular level of the putative endogenous agonist of IP(3)Rs which activates release of Ca(2+) from intracellular stores. It is concluded that intracellular free Ca(2+) acts on ACh receptor/ionic channel without activation of calmodulin and Ca(2+)/calmodulin-dependent protein kinase II.
Pivovarov
Arkady S
AS
Department of Higher Nervous Activity, Biological Faculty, Moscow Lomonosov State University, Moscow 119899, Russia.
Walker
Robert J
RJ
D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000737:chemistry / Q000378:metabolism*; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002147:Calmodulin / Q000037:antagonists & inhibitors / Q000378:metabolism*; D004594:Electrophysiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006372:Helix, Snails; D006493:Heparin / Q000494:pharmacology; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism*; D009249:NADP / Q000031:analogs & derivatives* / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D009479:Neuropeptides / Q000378:metabolism / Q000494:pharmacology*; D018408:Patch-Clamp Techniques; D011950:Receptors, Cholinergic / Q000378:metabolism; D018179:Receptors, Thrombin / Q000378:metabolism
D002147:Calmodulin; D004791:Enzyme Inhibitors; D009479:Neuropeptides; D011950:Receptors, Cholinergic; D018179:Receptors, Thrombin; C015541:thionicotinamide adenine dinucleotide phosphate; D009249:NADP; C024376:NAADP; D015544:Inositol 1,4,5-Trisphosphate; D006493:Heparin; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D000109:Acetylcholine; D002118:Calcium