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

Akio Iida,Makoto Kashiwayanagi

doi:10.1085/jgp.114.1.85

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.

Highlights

From the 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 of the olfactory sensory epithelium of Xenopus laevis
Anatomical observation has indicated that the olfactory sensory epithelium in the medial diverticulum comes into contact with air, while the epithelium in the lateral diverticulum is in contact with water (Altner, 1962)
On the assumption that these are odor receptors, the results suggest that olfactory neurons in the medial diverticulum are expected to respond to volatile odorants and neurons in the lateral diverticulum to water-soluble odorants

Summary

Akio Iida and Makoto Kashiwayanagi

From the 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. 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 induced current responses in 23 of 238 olfactory neurons These results suggest that the olfactory neurons respond to both water-soluble and volatile odorants. 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 ␮M or 1 mM These results suggest that olfactory neurons in the lateral diverticulum have receptors for amino acids and volatile odorants. We recorded the responses to water-soluble odorants as well as to volatile odorants from Xenopus laevis lateral olfactory receptor neurons under whole-cell voltage-clamp conditions. Many single olfactory neurons responded to a variety of amino acids, including acidic, basic, and neutral amino acids

Slice Preparation of Xenopus laevis Olfactory Sensory Epithelium

Data Recording and Analysis

Lucifer Yellow Dialysis

Cell Morphology

Findings

Voltage Response to Injected Current