Intracellular-Messenger-Mediated Cation Channels in Cultured Olfactory Receptor Neurons

After 2–3 weeks in culture, pupal olfactory receptor neurons from the antennae of male Manduca sexta respond to their species-specific sex pheromone by opening cation channels. These pheromone-dependent cation channels are the only channels previously found in cultured olfactory neurons that promote inward currents at membrane potentials more negative than the resting potential. The pheromone-dependent currents depend on external Ca²⁺ concentration. They are inwardly rectified with 10⁻⁷ mol l⁻¹ external Ca²⁺ and linear with 6mmol l⁻¹ Ca²⁺. This paper shows that perfusion of cultured olfactory receptor neurons with GTPγS, ATP, inositol 1,4,5,-trisphosphate or 10⁻⁶moll⁻¹ Ca²⁺ elicits cation currents resembling the pheromone-dependent cation currents in expressing inward rectification with 10⁻⁷ mol l⁻¹ external Ca²⁺ and being linear at external Ca²⁺ concentrations of 2 μmol l⁻¹ or more. Stimulation with protein kinase C also elicits cation currents that share properties with the pheromone-dependent cation currents. All agent-induced cation currents appear to depend either directly or indirectly on Ca²⁺concentration.