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Uptake of 5‐methyltetrahydrofolic acid by the rat jejunum.
Author(s) -
Blair J A,
Matty A J,
Razzaque A
Publication year - 1975
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1975.sp011050
Subject(s) - zwitterion , incubation , solvent drag , jejunum , q10 , chemistry , chromatography , acetic acid , concentration gradient , diffusion , biochemistry , biophysics , biology , anatomy , organic chemistry , microstructure , respiration , physics , molecule , grain boundary , crystallography , thermodynamics
1. Everted sacs of rat jejunum were used to study the transport of 5‐methyltetrahydrofolic acid at various concentrations and at different pHs. 2. The transport of 5‐methyltetrahydrofolic acid appeared to be linear with increasing incubation time at a 5‐methyltetrahydrofolic acid concentration of 10(−5) M in the incubating medium. Tissue uptake was much higher than serosal uptake. 3. At ‘zero’ concentration gradient of 5‐methyltetrahydrofolic acid, the transport from mucosal to serosal sides was negligible but tissue uptake was appreciable. 4. Reducing the incubation temperature from 37 to 27 degrees C gave a Q10 value of 1‐8. 5. The characteristics of 5‐methyltetrahydrofolic acid uptake suggested a non‐saturable transport mechanism. 6. Studies were also carried out with isolated mucosal epithelial cells at different incubation times and at different pH values. 7. The over‐all results suggest that 5‐methyltetrahydrofolic acid transport is most likely a passive diffusion of its zwitterion and also a solvent drag with water flow. 8. The 5‐methyltetrahydrofolic acid may be converted to its zwitterion in an acid microclimate at the surface of the intestinal absorbing cell.