Basal conductance of frog olfactory cilia.

The conductance of isolated frog olfactory cilia in the absence of odorants and second messengers has been measured. Current flowing through the pipette-membrane seal rather than the ciliary membrane was subtracted. In normal physiological solutions, each cilium has a conductance averaging 92 pS at the neuronal resting potential. This basal conductance allows current to be carried by K+ or Na+ but not by Cl-. In some cases, single channels with a unit conductance of 153 pS were observed. The conductance of the ciliary membrane implies a length constant for electrotonic conduction of about 160 microns. Since the reversal potential of the basal conductance is near the neuronal resting potential, it should help to stabilize the ciliary potential at some cost to stimulus transduction efficiency.