Ca2(+)-dependent adaptive properties in the solitary olfactory receptor cell of the newt.
The time-dependent decay of the olfactory receptor potential was analyzed with a solitary cell preparation by using the whole-cell patch clamp technique. During prolonged stimulation by 10 mM N-amylacetate under standard conditions, 17 out of 63 isolated olfactory cells responded with slow depolarization. Of these 17 cells, response amplitudes in 14 cells ('phasic/tonic' response) gradually decayed within 9 s, with a half-decay time of 1.71 +/- 1.10 s (mean +/- S.D.). The relative amplitude (ratio of tonic component to peak amplitude, Vtonic/Vmax) was 0.29 +/- 0.10. The response decay was attributed to the inactivation of the odorant-activated conductance. The recovery after inactivation, which was determined with double pulse experiments, was dependent on the resting interval. The inactivation of the odorant-activated conductance was found to be observed only when the external medium contained Ca2+. In addition, it was found that the odorant-activated conductance was capable of permeating Ca2+ (PCa/PNa = 6.5), and a rise in the internal EGTA concentration (to 50 mM) inhibited the inactivation. These observations suggest that the decay of the olfactory response to prolonged stimulation is mediated by Ca2+ influx.
Kurahashi
T
T
Institute of Biological Sciences, University of Tsukuba, Ibaraki, Japan.
Shibuya
T
T
D000818:Animals; D002118:Calcium / Q000502:physiology*; D002490:Central Nervous System / Q000502:physiology*; D004533:Egtazic Acid / Q000494:pharmacology; D004558:Electric Stimulation; D008564:Membrane Potentials; D009475:Neurons, Afferent / Q000502:physiology*; D009812:Odorants; D009831:Olfactory Mucosa / Q000294:innervation* / Q000502:physiology; D009833:Olfactory Pathways / Q000502:physiology*; D012455:Salamandridae / Q000502:physiology*
D004533:Egtazic Acid; D002118:Calcium