An analysis of Na+ currents in rat olfactory receptor neurons.
Na+ currents were observed in acutely-dissociated adult rat olfactory receptor neurons using the whole-cell recording techniques. The threshold for current activation was near -70 mV and currents were fully activated by -10 mV (midpoint: -45 mV). Steady-state inactivation was complete at potentials more positive than -70 mV and half complete at -110 mV (+/- less than 1, n = 8). Complete recovery from inactivation required one second at -100 mV (n = 7). The addition of 10 microM tetrodotoxin or 1 mM Zn2+ to the external solution was required to completely block the current. The current differs from those in amphibian and cultured neonatal rat olfactory neurons in its unusually negative voltage-dependence and slow recovery. Since mammalian olfactory neurons have very high input resistances, physiological resting potentials cannot usually be measured using whole-cell recording techniques. However, predominantly-capacitatively-coupled spikes activated by depolarisation were frequently observed in cell-attached patches. This indicates that the cells were excitable and implies that they must have had resting potentials more negative than -90 mV in order for this current to underlie the action potential.
Rajendra
S
S
School of Physiology and Pharmacology, University of New South Wales, Kensington, Sydney, Australia.
Lynch
J W
JW
Barry
P H
PH
D000200:Action Potentials; D000818:Animals; D007700:Kinetics; D008564:Membrane Potentials; D009832:Olfactory Nerve / Q000378:metabolism*; D051381:Rats; D011956:Receptors, Cell Surface / Q000378:metabolism*; D011984:Sensory Receptor Cells / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism*
D011956:Receptors, Cell Surface; D012964:Sodium