Electrical coupling in sustentacular cells of the mouse olfactory epithelium.

Sustentacular cells (SCs) line the apical surface of the olfactory epithelium (OE) and provide trophic, metabolic, and mechanical support for olfactory receptor neurons. Morphological studies have suggested that SCs possess gap junctions, although physiological evidence for gap junctional communication in mammalian SCs is lacking. In the present study we investigated whether coupling exists between SCs situated in tissue slices of OE from neonatal (P0-P4) mice. Using whole cell and cell-attached patch recordings from SCs, we demonstrate that SCs are electrically coupled by junctional resistances on the order of 300 M(omega). Under whole cell recording conditions, Alexa 488 added to the pipette solution failed to reveal dye coupling between SCs. Electrical coupling was deduced from the biexponential decay of capacitive currents recorded from SCs and from the bell-shaped voltage dependency of a P2Y-receptor-activated current, both of which were abolished by 18beta-glycyrrhetinic acid (20-50 microM), a blocker of gap junctions. These data provide strong evidence for functional coupling between SCs, the physiological importance of which is discussed.