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Responses of Xenopus laevis water nose to water-soluble and volatile odorants.

Iida A, Kashiwayanagi M - J. Gen. Physiol. (1999)

Bottom Line: Under voltage-clamp conditions, a voltage-dependent Na+ inward current, a sustained outward K+ current, and a Ca2+-activated K+ current were identified.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.

View Article: PubMed Central - PubMed

Affiliation: Graduate School of Pharmaceutical Sciences, Hokkaido University, Sapporo 060, Japan.

ABSTRACT
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.

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Inward currents in response to the amino acid cocktail (A and B). Inward currents in response to volatile odorant cocktail I (C) and cocktail II (D). All responses were recorded from different neurons (A∼D). (E) Inward currents in response to volatile odorant cocktail I, volatile odorant cocktail II, and the amino acid cocktail, respectively. The same inward current in response to the amino acid cocktail was shown with a short time scale in inset. All responses were recorded from the same neuron (E). The holding potential was −70 mV.
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Figure 4: Inward currents in response to the amino acid cocktail (A and B). Inward currents in response to volatile odorant cocktail I (C) and cocktail II (D). All responses were recorded from different neurons (A∼D). (E) Inward currents in response to volatile odorant cocktail I, volatile odorant cocktail II, and the amino acid cocktail, respectively. The same inward current in response to the amino acid cocktail was shown with a short time scale in inset. All responses were recorded from the same neuron (E). The holding potential was −70 mV.

Mentions: To evaluate the odor selectivity of the olfactory neuron of the lateral diverticulum, an amino acid cocktail and two volatile odorant cocktails were separately applied to neurons. The application of these three odorant cocktails induced inward currents in 46 of 238 neurons (Fig. 4). In 7 of 32 neurons responding to the amino acid cocktail, the magnitude of the inward current was reduced rapidly but not completely during continuous stimulation (Fig. 4 A). The remaining responses to the amino acid cocktail did not show sharp peaks (Fig. 4 B). The peak amplitude of inward currents in response to the amino acid cocktail ranged, typically, from 0 to 126 pA. The mean amplitude of inward currents in response to odorant cocktails was calculated using neurons that responded to any one of the three odorant cocktails.


Responses of Xenopus laevis water nose to water-soluble and volatile odorants.

Iida A, Kashiwayanagi M - J. Gen. Physiol. (1999)

Inward currents in response to the amino acid cocktail (A and B). Inward currents in response to volatile odorant cocktail I (C) and cocktail II (D). All responses were recorded from different neurons (A∼D). (E) Inward currents in response to volatile odorant cocktail I, volatile odorant cocktail II, and the amino acid cocktail, respectively. The same inward current in response to the amino acid cocktail was shown with a short time scale in inset. All responses were recorded from the same neuron (E). The holding potential was −70 mV.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2229635&req=5

Figure 4: Inward currents in response to the amino acid cocktail (A and B). Inward currents in response to volatile odorant cocktail I (C) and cocktail II (D). All responses were recorded from different neurons (A∼D). (E) Inward currents in response to volatile odorant cocktail I, volatile odorant cocktail II, and the amino acid cocktail, respectively. The same inward current in response to the amino acid cocktail was shown with a short time scale in inset. All responses were recorded from the same neuron (E). The holding potential was −70 mV.
Mentions: To evaluate the odor selectivity of the olfactory neuron of the lateral diverticulum, an amino acid cocktail and two volatile odorant cocktails were separately applied to neurons. The application of these three odorant cocktails induced inward currents in 46 of 238 neurons (Fig. 4). In 7 of 32 neurons responding to the amino acid cocktail, the magnitude of the inward current was reduced rapidly but not completely during continuous stimulation (Fig. 4 A). The remaining responses to the amino acid cocktail did not show sharp peaks (Fig. 4 B). The peak amplitude of inward currents in response to the amino acid cocktail ranged, typically, from 0 to 126 pA. The mean amplitude of inward currents in response to odorant cocktails was calculated using neurons that responded to any one of the three odorant cocktails.

Bottom Line: Under voltage-clamp conditions, a voltage-dependent Na+ inward current, a sustained outward K+ current, and a Ca2+-activated K+ current were identified.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.

View Article: PubMed Central - PubMed

Affiliation: Graduate School of Pharmaceutical Sciences, Hokkaido University, Sapporo 060, Japan.

ABSTRACT
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.

Show MeSH
Related in: MedlinePlus