Voltage-gated channel properties of epithelial cells in porcine vomeronasal organ.
Bipolar vomeronasal sensory neurons (VSNs) in the vomeronasal organ (VNO) are believed to detect pheromones in most mammals. The vomeronasal sensory epithelium (VSE) is composed of VSNs and supporting cells. There are morphological differences in VNOs between species. Many electrophysiological experiments have been performed on rodent VSEs but few on other mammals. We therefore investigated voltage-gated channel properties of cells in the porcine VSE using slice whole-cell voltage-clamp techniques. In immunohistochemical study of the porcine VSE, most PGP9.5-immunoreactive cells were found between the middle and basal region, and negative cells were distributed in the apical to middle region. Depolarizing pulses to epithelial cells from -90mV produced transient inward Na+ channel currents and sustained outward K+ channel currents with various amplitudes. The distribution of cells having high and low Na+ current densities was mostly consistent with the histological distribution of VSNs and supporting cells, respectively. The half-inactivation voltage of voltage-gated Na+ channels in supporting cells was 26mV more negative than that in VSNs. Voltage-gated K+ channel currents in both cell types were suppressed by tetraethylammonium to the same extent. VSNs possessed TTX-sensitive voltage-gated Na+ channels and Ni2+ -sensitive T-type Ca2+ channels. These results suggest that the histological distribution of porcine vomeronasal epithelial cells is more similar to the dog and goat than to rodents, and that the electrophysiological characteristics of porcine vomeronasal epithelial cells are similar to those of rodents. It is also suggested that porcine VSNs detecting pheromones generate action potentials through these channels.
Ishida
Tetsuya
T
Laboratory of Pharmacology, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo 060-0818, Japan.
Takei
Ryo
R
Gautam
Shree Hari
SH
Otsuguro
Ken-Ichi
K
Ohta
Toshio
T
Ito
Shigeo
S
Habara
Yoshiaki
Y
Saito
Toshiyuki
T
D000200:Action Potentials / Q000502:physiology; D000818:Animals; D015220:Calcium Channels / Q000378:metabolism; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism*; D019143:Evolution, Molecular; D005260:Female; D015640:Ion Channel Gating / Q000502:physiology*; D007473:Ion Channels / Q000378:metabolism*; D008564:Membrane Potentials / Q000502:physiology; D051379:Mice; D009924:Organ Culture Techniques; D018408:Patch-Clamp Techniques; D010675:Pheromones / Q000502:physiology; D026902:Potassium Channel Blockers / Q000494:pharmacology; D024642:Potassium Channels, Voltage-Gated / Q000378:metabolism; D015222:Sodium Channels / Q000378:metabolism; D013045:Species Specificity; D034421:Sus scrofa; D019789:Tetraethylammonium / Q000494:pharmacology; D043222:Ubiquitin Thiolesterase / Q000378:metabolism; D019147:Vomeronasal Organ / Q000166:cytology / Q000378:metabolism*
D015220:Calcium Channels; D007473:Ion Channels; D010675:Pheromones; D026902:Potassium Channel Blockers; D024642:Potassium Channels, Voltage-Gated; D015222:Sodium Channels; D019789:Tetraethylammonium; C489034:UCHL1 protein, rat; D043222:Ubiquitin Thiolesterase