Responses of Xenopus laevis water nose to water-soluble and volatile odorants.
Using the whole-cell mode of the patch-clamp technique, we recorded action potentials, voltage-activated cationic currents, and inward currents in response to water-soluble and volatile odorants from receptor neurons in the lateral diverticulum (water nose) of the olfactory sensory epithelium of Xenopus laevis. The resting membrane potential was -46.5 +/- 1.2 mV (mean +/- SEM, n = 68), and a current injection of 1-3 pA induced overshooting action potentials. Under voltage-clamp conditions, a voltage-dependent Na+ inward current, a sustained outward K+ current, and a Ca2+-activated K+ current were identified. Application of an amino acid cocktail induced inward currents in 32 of 238 olfactory neurons in the lateral diverticulum under voltage-clamp conditions. Application of volatile odorant cocktails also induced current responses in 23 of 238 olfactory neurons. These results suggest that the olfactory neurons respond to both water-soluble and volatile odorants. The application of alanine or arginine induced inward currents in a dose-dependent manner. More than 50% of the single olfactory neurons responded to multiple types of amino acids, including acidic, neutral, and basic amino acids applied at 100 microM or 1 mM. These results suggest that olfactory neurons in the lateral diverticulum have receptors for amino acids and volatile odorants.
Graduate School of Pharmaceutical Sciences, Hokkaido University, Sapporo 060, Japan.
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Iida
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Kashiwayanagi
D000200:Action Potentials / Q000502:physiology; D000818:Animals; D009475:Neurons, Afferent / Q000166:cytology / Q000502:physiology*; D009812:Odorants; D009833:Olfactory Pathways / Q000166:cytology / Q000502:physiology; D018408:Patch-Clamp Techniques; D012679:Sense Organs / Q000502:physiology*; D012903:Smell / Q000502:physiology*; D012995:Solubility; D013268:Stimulation, Chemical; D014867:Water; D014982:Xenopus laevis / Q000502:physiology*
D014867:Water