Dialysis of inositol 1,4,5-trisphosphate induces inward currents and Ca2+ uptake in frog olfactory receptor cells

Abstract

Frog olfactory receptor cells (Rana ridibunda) were isolated with an enzyme-free procedure and loaded with fura-2 from the patch pipette. The cells responded to superfusion with "IP3-odorants" with an inward current and an increase of the intracellular Ca2+ concentration. [Ca2+]i. An odorant-induced inward current and an increase in [Ca2+]i were also observed while flooding cells with 1 mM cAMP from the pipette, a condition which drives the cAMP signal pathway into adaptation. Flooding of cells with 50 microM IP3 from the pipette also induced an inward current with an increase in [Ca2+]i in normal Ringer solution and an inward current without changes in [Ca2+]i in Ca(2+)-free solution. The experiments suggest that IP3 activates a cation channel at the plasma membrane, allowing inflow of Na+ and Ca2+ ions.