Relationship between blood lactate concentration and substrate utilization during exercise in type 2 diabetic postmenopausal women.
Increased blood lactate concentration and alterations of substrate utilization have been shown to be partly involved in development of insulin resistance in obese and type 2 diabetic patients. As blood represents the first great distribution space and participates to lactate exchange in whole body, we investigated lactate transport in red blood cells at rest and the potential relationships between elevated blood lactate and substrate utilization in 7 obese controls and 7 obese type 2 diabetic postmenopausal women during an incremental exercise test. Blood samples were collected at rest, 30%, 50%, and 60% of maximal power and at 8 and 20 minutes of recovery time. Baseline lactatemia and its increase during exercise were higher in the diabetic group (P < .05). We found a negative correlation between basal and 30% maximal power lactatemia and 2 indexes of substrate utilization (crossover point: r = -0.79, r = -0.82 and maximal lipid oxidation point: r = -0.83, r = -0.80; P < .05) in diabetic group only. Furthermore, there were positive correlations between the affinity constant, maximal velocity transport, and basal lactate level in diabetic subjects (r = 0.91 and r = 0.73, respectively; P < .05). These results show that the elevation of blood lactate is associated with a greater carbohydrate oxidation in type 2 diabetes, but the mechanisms underlying the alteration of substrate utilization need to be clarified. Furthermore, increased lactate levels cannot be explained by alterations of lactate transport in red blood cells, but it could affect monocarboxylate transporter 1 properties.
Metz
Lore
L
Département de physiologie des Interactions EA 701 Muscles et Pathologies Chroniques, Institut de biologie, CS 89508, 34060 Montpellier Cedex 2, France. lore_metz@hotmail.com
Sirvent
Pascal
P
Py
Guillaume
G
Brun
Jean-Frederic
JF
Fédou
Christine
C
Raynaud
Eric
E
Mercier
Jacques
J
D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000503:physiopathology*; D004734:Energy Metabolism / Q000502:physiology; D004912:Erythrocytes / Q000378:metabolism; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D019344:Lactic Acid / Q000097:blood*; D008875:Middle Aged; D027501:Monocarboxylic Acid Transporters / Q000378:metabolism; D010101:Oxygen Consumption / Q000502:physiology; D017698:Postmenopause; D027981:Symporters / Q000378:metabolism; D000099233:Monocarboxylate Transport Protein 1
D019344:Lactic Acid; D027501:Monocarboxylic Acid Transporters; D027981:Symporters; D000099233:Monocarboxylate Transport Protein 1