TRANSCELLULAR AND PARACELLULAR PATHWAYS IN LINGUAL EPITHELIA AND THEIR INFLUENCE IN TASTE TRANSDUCTION

The lingual epithelium is innervated by special sensory (taste) and ge neral sensory (trigeminal) nerves that transmit information about chem ical stimuli introduced into the mouth to the higher brain centers. Un derstanding the cellular mechanisms involved in eliciting responses fr om these nerves requires a detailed understanding of the contributions of both the paracellular and transcellular pathways. In this paper we focus on the contribution of these 2 pathways to the responses of sal ts containing sodium and various organic anions in the presence and ab sence of amiloride. Electrophysiological recordings from trigeminal ne rves, chorda tympani nerves, and isolated lingual epithelia were combi ned with morphological studies investigating the location (and permeab ility) of tight junctions, the localization of amiloride-inhibitable c hannels, and Na-K-ATPase in taste and epithelial cells. Based on these measurements, we conclude that diffusion across tight junctions can m odulate chorda tympani and trigeminal responses to sodium-containing s alts and rationalize the enhancement of taste responses to saccharides by NaCl. (C) 1993 Wiley-Liss, Inc.