Voltage-dependent currents in microvillar receptor cells of the frog vomeronasal organ.
Vomeronasal receptor cells are differentiated bipolar neurons with a long dendrite bearing numerous microvilli. Isolated cells (with a mean dendritic length of 65 microns) and cells in mucosal slices were studied using whole-cell and Nystatin-perforated patch-clamp recordings. At rest, the membrane potential was -61 +/- 13 mV (mean +/- SD; n = 61). Sixty-four per cent of the cells had a resting potential in the range of -60 to -86 mV, with almost no spontaneous action potential. The input resistance was in the G omega range and overshooting repetitive action potentials were elicited by injecting depolarizing current pulses in the range of 2-10 pA. Voltage-dependent currents were characterized under voltage-clamp conditions. A transient fast inward current activating near -45 mV was blocked by tetrodotoxin. In isolated cells, it was half-deactivated at a membrane potential near -75 mV. An outward K+ current was blocked by internal Cs+ ions or by external tetraethylammonium or Ba2+ ions. A calcium-activated voltage-dependent potassium current was blocked by external Cd2+ ions. A voltage-dependent Ca2+ current was observed in an iso-osmotic BaCl2 solution. Finally, a hyperpolarization-activated inward current was recorded. Voltage-dependent currents in these microvillar olfactory receptor neurons appear qualitatively similar to those already described in ciliated olfactory receptor cells located in the principal olfactory epithelium.
Trotier
D
D
Laboratoire de Neurobiologie Sensorielle, EPHE, Massy, France.
Døving
K B
KB
Rosin
J F
JF
D000818:Animals; D002118:Calcium / Q000502:physiology; D002628:Chemoreceptor Cells / Q000166:cytology / Q000502:physiology*; D004594:Electrophysiology; D008564:Membrane Potentials; D008871:Microvilli / Q000502:physiology; D009296:Nasal Cavity / Q000502:physiology*; D009300:Nasal Septum / Q000502:physiology*; D009474:Neurons / Q000502:physiology / Q000648:ultrastructure; D011188:Potassium / Q000502:physiology; D011893:Rana esculenta / Q000502:physiology*; D013779:Tetrodotoxin / Q000494:pharmacology
D013779:Tetrodotoxin; D011188:Potassium; D002118:Calcium