A proton gradient, not a sodium gradient, is the driving force for active transport of lactate in rabbit intestinal brush-border membrane vesicles.
An inward-directed H+ gradient markedly stimulated lactate uptake in rabbit intestinal brush-border membrane vesicles, and uphill transport against a concentration gradient could be demonstrated under these conditions. Uptake of lactate was many-fold greater in the presence of a H+ gradient than in the presence of a Na+ gradient. Moreover, there was no evidence for uphill transport of lactate in the presence of a Na+ gradient. The H+-gradient-dependent stimulation of lactate uptake was not due to the effect of a H+-diffusion potential. The uptake process in the presence of a H+ gradient was saturable [Kt (concn. giving half-maximal transport) for lactate 12.7 +/- 4.5 mM] and was inhibited by many monocarboxylates. It is concluded that a H+ gradient, not a Na+ gradient, is the driving force for active transport of lactate in rabbit intestinal brush-border membrane vesicles.
Tiruppathi
C
C
Department of Cell and Molecular Biology, Medical College of Georgia, Augusta 30912-2100.
Balkovetz
D F
DF
Ganapathy
V
V
Miyamoto
Y
Y
Leibach
F H
FH
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D002264:Carboxylic Acids / Q000494:pharmacology; D011232:Chemical Precipitation; D005947:Glucose / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007413:Intestinal Mucosa / Q000187:drug effects / Q000378:metabolism*; D007773:Lactates / Q000378:metabolism*; D019344:Lactic Acid; D008564:Membrane Potentials; D008871:Microvilli / Q000187:drug effects / Q000378:metabolism; D011522:Protons; D011817:Rabbits; D012964:Sodium / Q000378:metabolism
D002264:Carboxylic Acids; D007773:Lactates; D011522:Protons; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; D019344:Lactic Acid; D012964:Sodium; D005947:Glucose; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid