Myocardial metabolism of exogenous FDP is consistent with transport by a dicarboxylate transporter.
The extent to and the mechanism by which fructose-1,6-bisphosphate (FDP) crosses cell membranes are unknown. We hypothesized that its transport is either via band 3 or a dicarboxylate transporter. The question was addressed in isolated Langendorff rat hearts perfused under normoxic conditions. Groups of hearts received the following metabolic substrates (in mM): 5 FDP; 5 FDP + either 5, 10, or 20 fumarate; 10 FDP and either 5, 10, or 20 fumarate; or 5 FDP + 2 4,4'-dinitrostilbene-2,2'-disulfonate (DNDS), a band 3 inhibitor. FDP uptake and metabolism were measured as production of [(13)C]lactate from [(13)C]FDP or (14)CO(2) and [(14)C]lactate from uniformly labeled [(14)C]FDP in sample perfusates. During 30 min of perfusion, FDP metabolism was 12.4 +/- 2.6 and 31.2 +/- 3.0 micromol for 5 and 10 mM FDP, respectively. Addition of 20 mM fumarate reduced FDP metabolism over a 30-min perfusion period to 3.1 +/- 0.6 and 6.3 +/- 0.5 micromol for 5 and 10 mM FDP groups, respectively. DNDS did not affect FDP utilization. These data are consistent with transport of FDP by a dicarboxylate transport system.
Hardin
C D
CD
Department of Physiology, University of Missouri, Columbia, 65212, USA. hardinc@missouri.edu
Lazzarino
G
G
Tavazzi
B
B
Di Pierro
D
D
Roberts
T M
TM
Giardina
B
B
Rovetto
M J
MJ
D000818:Animals; D001457:Anion Exchange Protein 1, Erythrocyte / Q000378:metabolism; D001692:Biological Transport / Q000502:physiology; D002245:Carbon Dioxide / Q000378:metabolism; D002250:Carbon Radioisotopes; D029382:Dicarboxylic Acid Transporters / Q000378:metabolism*; D004734:Energy Metabolism / Q000502:physiology*; D005635:Fructosediphosphates / Q000493:pharmacokinetics*; D005650:Fumarates / Q000493:pharmacokinetics; D006019:Glycolysis / Q000502:physiology; D006863:Hydrogen-Ion Concentration; D019344:Lactic Acid / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D017202:Myocardial Ischemia / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism*; D051381:Rats; D012508:Sarcolemma / Q000378:metabolism
D001457:Anion Exchange Protein 1, Erythrocyte; D002250:Carbon Radioisotopes; D029382:Dicarboxylic Acid Transporters; D005635:Fructosediphosphates; D005650:Fumarates; D002245:Carbon Dioxide; D019344:Lactic Acid; C032005:fumaric acid; C029063:fructose-1,6-diphosphate