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Ethanol selectively affects Na + ‐gradient dependent intestinal transport systems
Author(s) -
O'Neill Brigitte,
Weber Fritz,
Hornig Dietrich,
Semenza Giorgio
Publication year - 1986
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(86)80073-4
Subject(s) - chemistry , ethanol , biophysics , biochemistry , biology
Moderate concentrations of ethanol reduce the velocity of uptake of three representative Na + ‐symport systems (D‐glucose, L‐alanine, L‐ascorbate), whether electrogenic (the first two) or electroneutral (L‐ascorbate). This ‘inhibition’ is observed only if these transport systems are tested in the presence of an initial Na + gradient (out > in); no inhibition is found in tracer‐equilibrium exchange measurements. A representative Na + ‐ in dependent system (D‐fructose) is not inhibited by ethanol. ‘Passive diffusion’ (measured as uptake of L‐glucose) is increased somewhat by alcohol. All these observations can be rationalized [as suggested by Tillotson et al. (1981) Arch. Biochem. Biophys. 207, 360–370] by an effect of ethanol on passive diffusion, which leads to a faster collapse of the Na + gradient, with the resulting reduction of the uptake velocities of Na + ‐dependent transport systems when tested with the added driving force of an Na + out → in gradient.