2ND-MESSENGER-CONTROLLED MEMBRANE CONDUCTANCE IN LOCUST (LOCUSTA-MIGRATORIA) OLFACTORY NEURONS

The membrane conductance of olfactory neurons of Locusta migratoria wa s examined using the whole-cell configuration of the patch-clamp techn ique. Intracellular application of the second messenger inositol 1,4,5 trisphosphate (IP3) via a dual pipette technique elicited a clear inc rease in the membrane conductance. The IP3-induced conductance increas ed due to a rise in the extracellular concentration of calcium from 10 0 mu M to 4 mM. Micromolar concentrations of ruthenium red partially b locked the IP3-induced increase in membrane conductance. Stimulating o lfactory neurons with odour (hexenoic acid) resulted in an increase in the membrane conductance partially similar to that mediated IP3. Thes e findings suggest that stimulation with appropriate odours as well as intracellular application of IP3 activate the same calcium-permeable ion channels in the plasma membrane of insect olfactory neurons. (C) 1 997 Elsevier Science Ltd.