Inositol-trisphosphate-dependent calcium currents precede cation currents in insect olfactory receptor neurons in vitro.
Specialized olfactory receptor neurons in insects respond to species-specific sex pheromones with transient rises in inositol trisphosphate and by opening pheromone-dependent cation channels. These channels resemble cation channels which are directly or indirectly Ca(2+)-dependent. But there appear to be no internal Ca2+ stores in the outer dendrite where the olfactory transduction cascade is thought to start. Hence, it remains to be determined whether an influx of external Ca2+ precedes pheromone-dependent cation currents. Patch clamp measurements in cultured olfactory receptor neurons from Manduca sexta reveal that a transient inward current precedes pheromone-dependent cation currents. A transient inositol trisphosphate-dependent Ca2+ current, also preceding cation currents with the characteristics of pheromone-dependent cation currents, shares properties with the transient pheromone-dependent current. These results match the biochemical measurements with the electrophysiological data obtained in insect olfactory receptor neurons.
Stengl
M
M
Institut für Zoologie, Universität Regensburg, Germany.
D000818:Animals; D015220:Calcium Channels / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D004594:Electrophysiology; D007293:Inosine Triphosphate / Q000502:physiology*; D007473:Ion Channels / Q000187:drug effects / Q000502:physiology*; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009036:Moths / Q000502:physiology*; D009475:Neurons, Afferent / Q000187:drug effects / Q000502:physiology*; D018035:Receptors, Odorant / Q000187:drug effects / Q000502:physiology*; D012724:Sex Attractants / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013268:Stimulation, Chemical; D013757:Tetraethylammonium Compounds / Q000494:pharmacology; D013779:Tetrodotoxin / Q000494:pharmacology
D015220:Calcium Channels; D007473:Ion Channels; D018035:Receptors, Odorant; D012724:Sex Attractants; D013757:Tetraethylammonium Compounds; D007293:Inosine Triphosphate; D013779:Tetrodotoxin