title: Effects of streptozotocin-induced diabetes on markers of skeletal muscle metabolism and monocarboxylate transporter 1 to monocarboxylate transporter 4 transporters.
abstract: Diabetes is known to alter both oxidative and glycolytic pathways in a fiber type-dependent manner. In various skeletal muscles of normal rats, monocarboxylate transporter 1 (MCT1) has been found to be highly correlated to lactate uptake, as well as to oxidative capacity, whereas the distribution and characteristics of MCT4 make it a good candidate for the extrusion of lactic acid from glycolytic muscle cells. Since a previous study found decreased sarcolemmal lactate uptake in streptozotocin (STZ)-diabetic rats, we investigated the presence of MCT1 in relation to enzymatic markers of both oxidative and glycolytic pathways, as well as MCT4 content, in STZ-diabetic rats. Soleus (SOL), red tibialis anterior (RTA), extensor digitorus longus (EDL), heart, and preparations of purified sarcolemmal vesicles (SV) from control and STZ-diabetic rats were harvested for MCT1 and MCT4 content, citrate synthase activity (CS), and lactate dehydrogenase (LDH) isozymes. Basal blood lactate concentration was increased by 38% in the diabetic rats (close to 1.91 mmol/L). However, no change was found in either MCT1 or MCT4 content in these rats. The diabetic rats presented fiber type-specific decrease in CS activity. We noted a redistribution in LDH isozymes in diabetic muscles with a general increase in type H-LDH. Regression analyses indicated (1) a strong relationship between LDH-4 and LDH-5 and (2) MCT1 was still correlated with CS activity in diabetic muscles. These results suggest that diabetes-induced hyperlactatemia is not associated with changes in MCT1 or MCT4 expression, but with alterations of oxidative and glycolytic enzymes.
authors.affiliation: Département de Physiologie, Laboratoire de Physiologie des Interactions, Institut de Biologie, Montpellier, France.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Py
authors.forename: Karen
authors.initials: K
authors.lastname: Lambert
authors.forename: Ollivier
authors.initials: O
authors.lastname: Milhavet
authors.forename: Nicolas
authors.initials: N
authors.lastname: Eydoux
authors.forename: Christian
authors.initials: C
authors.lastname: Préfaut
authors.forename: Jacques
authors.initials: J
authors.lastname: Mercier
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000032:analysis; D001786:Blood Glucose; D001835:Body Weight; D002352:Carrier Proteins / Q000378:metabolism*; D002950:Citrate (si)-Synthase / Q000378:metabolism; D003921:Diabetes Mellitus, Experimental / Q000139:chemically induced / Q000378:metabolism*; D004195:Disease Models, Animal; D007328:Insulin / Q000097:blood; D007527:Isoenzymes / Q000378:metabolism; D007657:Ketone Bodies / Q000097:blood; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D019344:Lactic Acid / Q000097:blood; D008297:Male; D026901:Membrane Transport Proteins; D027501:Monocarboxylic Acid Transporters / Q000378:metabolism*; D009124:Muscle Proteins; D018482:Muscle, Skeletal / Q000737:chemistry / Q000378:metabolism*; D009206:Myocardium / Q000737:chemistry / Q000378:metabolism; D051381:Rats; D012508:Sarcolemma / Q000737:chemistry; D013311:Streptozocin; D027981:Symporters / Q000378:metabolism*; D000099233:Monocarboxylate Transport Protein 1
chemical_list: D015415:Biomarkers; D001786:Blood Glucose; D002352:Carrier Proteins; D002950:Citrate (si)-Synthase; D007328:Insulin; D007527:Isoenzymes; D007657:Ketone Bodies; D007770:L-Lactate Dehydrogenase; D019344:Lactic Acid; D026901:Membrane Transport Proteins; D027501:Monocarboxylic Acid Transporters; D009124:Muscle Proteins; D013311:Streptozocin; D027981:Symporters; D000099233:Monocarboxylate Transport Protein 1; C491393:Mct3 protein, rat; C490427:SLC16A7 protein, human; C516342:Slc16a3 protein, rat; C091633:Slc16a7 protein, rat