Ca2+ resting current and Ca2+-induced Ca2+ release in insect neurosecretory neurons.
The effect of a Ca2+ resting current on spiking and intracellular Ca2+ concentration [Ca2+]i of isolated cockroach dorsal unpaired median neurons was investigated by combining microfluometry (Fura2) with patchclamping. The resting current was reduced by 10 microM 5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB) and 10 microM mefenamic acid, which caused slower spiking of cells. Up-modulation of the resting current by neurohormone D (NHD, 100 fM to 10 pM) transiently increased [Ca2+]i. This Ca2+ transient was largely reduced by the ryanodine receptor antagonist dantrolene (10 microM) but it was not reduced by the IP3-receptor antagonist heparin which indicates Ca2+-induced Ca2+ release. The NHD-effect on [Ca2+]i was strongly attenuated by NPPB and mefenamic acid. Thus, NHD caused Ca2+-induced Ca2+ release by enhancing the Ca2+ resting current.
Heine
M
M
Institut für Allgemeine Zoologie und Tierphysiologie, Friedrich-Schiller-Universität Jena, Germany.
Wicher
D
D
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D000925:Anticoagulants / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D003620:Dantrolene / Q000494:pharmacology; D004594:Electrophysiology; D006493:Heparin / Q000494:pharmacology; D007301:Insect Hormones / Q000494:pharmacology; D008528:Mefenamic Acid / Q000494:pharmacology; D009125:Muscle Relaxants, Central / Q000494:pharmacology; D009474:Neurons / Q000737:chemistry* / Q000187:drug effects / Q000378:metabolism*; D009479:Neuropeptides / Q000494:pharmacology; D009490:Neurosecretory Systems / Q000737:chemistry / Q000166:cytology; D018377:Neurotransmitter Agents / Q000378:metabolism; D009579:Nitrobenzoates / Q000494:pharmacology; D010526:Periplaneta; D019837:Ryanodine Receptor Calcium Release Channel / Q000378:metabolism*; D015854:Up-Regulation / Q000187:drug effects
D000925:Anticoagulants; D016861:Cyclooxygenase Inhibitors; D007301:Insect Hormones; D009125:Muscle Relaxants, Central; D009479:Neuropeptides; D018377:Neurotransmitter Agents; D009579:Nitrobenzoates; D019837:Ryanodine Receptor Calcium Release Channel; D008528:Mefenamic Acid; C058176:5-nitro-2-(3-phenylpropylamino)benzoic acid; D006493:Heparin; C043192:glutamyl-valyl-asparaginyl-phenylalanyl-seryl-prolyl-asparaginyl-tryptophanamide; D003620:Dantrolene; D002118:Calcium