Effect of Na+ on intestinal succinate transport and metabolism in vitro.
The effect of Na+ on 14CO2 production from [14C]succinate was studied in isolated rat enterocytes, and Na+-dependent succinate transport was characterized in pig intestinal brush-border membrane vesicles. The production of 14CO2 from [14C]succinate by enterocytes was decreased 12-fold when Na+ was replaced by N-methyl-D-glucamine in the absence of glutamine and 20-fold in the presence of 0.2 or 0.5 mM glutamine. The ratio of 14CO2 produced from [1,4-14C]succinate to that produced by [2,3-14C]succinate was not affected by Na+ replacement, indicating that the pattern of tricarboxylic acid cycle metabolism was not altered. The uptake of [14C]succinate by brush-border membrane vesicles was stimulated 10-fold in the presence of 100 mM NaCl compared with 100 mM KCl. When succinate uptake was corrected to transport into an osmotically sensitive space, the magnitude of the Na+ stimulation was 20-fold. Succinate transport into brush-border membrane vesicles was Na+ dependent, electroneutral, nonconcentrative, with an apparent Na+-succinate coupling ratio of 2:1. Results of this study indicate that Na+-stimulated CO2 production by enterocytes can be explained by the effect of Na+ on succinate transport across the brush-border membrane.
Moe
A J
AJ
George Washington University Medical Center, Washington, DC 20037.
Mallet
R T
RT
Jackson
M J
MJ
Hollywood
J A
JA
Kelleher
J K
JK
D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D066298:In Vitro Techniques; D007413:Intestinal Mucosa / Q000378:metabolism; D007422:Intestines / Q000187:drug effects*; D008297:Male; D010084:Oxidation-Reduction; D051381:Rats; D011919:Rats, Inbred Strains; D012964:Sodium / Q000494:pharmacology*; D013386:Succinates / Q000493:pharmacokinetics*; D013552:Swine; D014634:Valinomycin / Q000494:pharmacology
D013386:Succinates; D014634:Valinomycin; D000584:Amiloride; D012964:Sodium