[Ligand-dependent ionic conductivity in olfactory cilia]

We have examined the membrane conductance in the frog olfactory receptor cilia by the "whole cilia patch" method according to Kleen and Gesteland [1]. We always observed the cyclic AMP-gated conductance as reported previously on the excited inside-out membrane patch from the cilium. However, we could not detect a significant indication of the IP3-gated conductance in the ciliary membrane. On the contrary, Ca(2+)-gated chloride conductance was detected in most cilia. The mean value of this conductance was more than 10% of the cAMP-gated conductance measured in divalent cation free solution. This result may indicate the certain role of the chloride channel in the generation of the olfactory receptor potential.