title: Mechanism of epithelial lithium transport. Evidence for basolateral Na:Na and Na:Li exchange.
abstract: Measurement of transmural sodium fluxes across isolated, ouabain-inhibited turtle colon in the presence of a serosal-to-mucosal sodium gradient shows that in the absence of active transport the amiloride-sensitive cellular path contains at least two routes for the transmural movement of sodium and lithium, one a conductive path and the other a nonconductive, cation-exchange mechanism. The latter transport element can exchange lithium for sodium, and the countertransport of these two cations provides a mechanistic basis for the ability of tight epithelia to actively absorb lithium despite the low affinity of the basolateral Na/K-ATPase for this cation.
mesh_terms: D000818:Animals; D001692:Biological Transport; D001696:Biomechanical Phenomena; D002412:Cations / Q000378:metabolism; D003106:Colon / Q000378:metabolism*; D004848:Epithelium / Q000378:metabolism; D007474:Ion Exchange; D008094:Lithium / Q000378:metabolism*; D008433:Mathematics; D010042:Ouabain / Q000494:pharmacology; D012964:Sodium / Q000378:metabolism*; D014426:Turtles / Q000378:metabolism*
chemical_list: D002412:Cations; D010042:Ouabain; D008094:Lithium; D012964:Sodium