title: Active electrolyte transport in mammalian buccal mucosa.
abstract: The transmural electrical potential difference (PD) was measured in vivo across the buccal mucosa of humans and experimental animals. Mean PD was -31 +/- 2 mV in humans, -34 +/- 2 mV in dogs, -39 +/- 2 mV in rabbits, and -18 +/- 1 mV in hamsters. The mechanisms responsible for this PD were explored in Ussing chambers using dog buccal mucosa. After equilibration, mean PD was -16 +/- 2 mV, short-circuit current (Isc) was 15 +/- 1 microA/cm2, and resistance was 1,090 +/- 100 omega.cm2, the latter indicating an electrically "tight" tissue. Fluxes of [14C]mannitol, a marker of paracellular permeability, varied directly with tissue conductance. The net fluxes of 22Na and 36Cl were +0.21 +/- 0.05 and -0.04 +/- 0.02 mueq/h.cm2, respectively, but only the Na+ flux differed significantly from zero. Isc was reduced by luminal amiloride, serosal ouabain, or by reducing luminal Na+ below 20 mM. This indicated that the Isc was determined primarily by active Na+ absorption and that Na+ traverses the apical membrane at least partly through amiloride-sensitive channels and exits across the basolateral membrane through Na+-K+-ATPase activity. We conclude that buccal mucosa is capable of active electrolyte transport and that this capacity contributes to generation of the buccal PD in vivo.
mesh_terms: D000328:Adult; D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D001693:Biological Transport, Active; D006224:Cricetinae; D004285:Dogs; D004553:Electric Conductivity; D004573:Electrolytes / Q000378:metabolism*; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D008297:Male; D008353:Mannitol / Q000378:metabolism; D008564:Membrane Potentials; D009061:Mouth Mucosa / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D013045:Species Specificity
chemical_list: D004573:Electrolytes; D008353:Mannitol; D000584:Amiloride