Electrical properties of cells from human olfactory epithelium

The electrical properties of olfactory cells (OCs) are typically examined using animals such as newts, mice, and frogs, with few studies on human OCs. This study investigated the electrical properties of human cells from olfactory epithelium (hCOEs) obtained from subjects of olfactory epithelium showing no clinical symptoms during endoscopic sinus surgery. hCOEs were isolated by collagenase treatment for whole-cell patch clamp recording. The identity of the cells was confirmed by immunohistochemistry with an antibody against olfactory maker protein. Under the voltage clamp with the whole-cell recording configuration, the voltage-gated currents of isolated hCOEs were recorded when the membrane potential was depolarized from a holding potential of −100 mV in a stepwise manner between −90 mV and + 40 mV. Only one of 14 hCOE samples expressed a transient inward current at the depolarizing voltage step that was activated by depolarization beyond −40 mV and reached a peak at −30 mV. Delayed and sustained outward currents (444 ± 106 pA at + 40 mV pulse; n = 20) were suppressed by tetraethyl ammonium (n = 3), which is consistent with the properties of newt OCs. Most hCOEs did not exhibit the transient inward current observed in animal models. These findings provide insight into the physiological basis of the unique aspects of human olfactory signal transduction.