ESTIMATION OF THE JUNCTIONAL RESISTANCE BETWEEN ELECTRICALLY COUPLED RECEPTOR-CELLS IN NECTURUS TASTE-BUDS

Junctional resistance between coupled receptor cells in Necturus taste buds was estimated by modeling the results from single patch pipette voltage clamp studies on lingual slices. The membrane capacitance and input resistance of coupled taste receptor cells were measured to monitor electrical coupling and the results compared with those calculated by a simple model of electrically coupled taste cells. Coupled receptor cells were modeled by two identical receptor cells connected via a junctional resistance. On average, the junctional resistance was similar to 200-300 M Omega. This was consistent with the electrophysiological recordings. A junctional resistance of 200-300 M Omega is close to the threshold for Lucifer yellow dye-coupling detection (similar to 500 M Omega). Therefore, the true extent of coupling in taste buds might be somewhat greater than that predicted from Lucifer yellow dye coupling. Due to the high input resistance of single taste receptor cells (>1 G Omega), a junctional resistance of 200-300 M Omega assures a substantial electrical communication between coupled taste cells, suggesting that the electrical activity of coupled cells might be synchronized.