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-mu-m. 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.