Abstract.
L-lactate transport mechanism across rat jejunal enterocyte was investigated using isolated membrane vesicles. In basolateral membrane vesicles l-lactate uptake is stimulated by an inwardly directed H+ gradient; the effect of the pH difference is drastically reduced by FCCP, pCMBS and phloretin, while furosemide is ineffective. The pH gradient effect is strongly temperature dependent. The initial rate of the proton gradient-induced lactate uptake is saturable with respect to external lactate with a K m of 39.2 ± 4.8 mm and a J max of 8.9 ± 0.7 nmoles mg protein−1 sec−1. A very small conductive pathway for l-lactate is present in basolateral membranes. In brush border membrane vesicles both Na+ and H+ gradients exert a small stimulatory effect on lactate uptake. We conclude that rat jejunal basolateral membrane contains a H+-lactate cotransporter, whereas in the apical membrane both H+-lactate and Na+-lactate cotransporters are present, even if they exhibit a low transport rate.
Author information
Authors and Affiliations
Additional information
Received: 22 October 1996/Revised: 11 March 1997
Rights and permissions
About this article
Cite this article
Orsenigo, M., Tosco, M., Laforenza, U. et al. Facilitated Transport of Lactate by Rat Jejunal Enterocyte . J. Membrane Biol. 158 , 257 –264 (1997). https://doi.org/10.1007/s002329900262
Issue Date:
DOI: https://doi.org/10.1007/s002329900262