Heart-type fatty acid-binding protein reciprocally regulates glucose and fatty acid utilization during exercise.

Shearer J, Fueger PT, Rottman JN, Bracy DP, Binas B, Wasserman DH
Am J Physiol Endocrinol Metab. 2005 288 (2): E292-7

PMID: 15454399 · DOI:10.1152/ajpendo.00287.2004

The role of heart-type cytosolic fatty acid-binding protein (H-FABP) in mediating whole body and muscle-specific long-chain fatty acid (LCFA) and glucose utilization was examined using exercise as a phenotyping tool. Catheters were chronically implanted in a carotid artery and jugular vein of wild-type (WT, n = 8), heterozygous (H-FABP(+/-), n = 8), and null (H-FABP(-/-), n = 7) chow-fed C57BL/6J mice, and mice were allowed to recover for 7 days. After a 5-h fast, conscious, unrestrained mice were studied during 30 min of treadmill exercise (0.6 mph). A bolus of [(125)I]-15-(p-iodophenyl)-3-R,S-methylpentadecanoic acid and 2-deoxy-[(3)H]glucose was administered to obtain rates of whole body metabolic clearance (MCR) and indexes of muscle LCFA (R(f)) and glucose (R(g)) utilization. Fasting, nonesterified fatty acids (mM) were elevated in H-FABP(-/-) mice (2.2 +/- 0.9 vs. 1.3 +/- 0.1 and 1.3 +/- 0.2 for WT and H-FABP(+/-)). During exercise, blood glucose (mM) increased in WT (11.7 +/- 0.8) and H-FABP(+/-) (12.6 +/- 0.9) mice, whereas H-FABP(-/-) mice developed overt hypoglycemia (4.8 +/- 0.8). Examination of tissue-specific and whole body glucose and LCFA utilization demonstrated a dependency on H-FABP with exercise in all tissues examined. Reductions in H-FABP led to decreasing exercise-stimulated R(f) and increasing R(g) with the most pronounced effects in heart and soleus muscle. Similar results were seen for MCR with decreasing LCFA and increasing glucose clearance with declining levels of H-FABP. These results show that, in vivo, H-FABP has reciprocal effects on glucose and LCFA utilization and whole body fuel homeostasis when metabolic demands are elevated by exercise.

MeSH Terms (13)

Animals Blood Glucose Carrier Proteins Fatty Acid-Binding Proteins Fatty Acids Homeostasis Metabolic Clearance Rate Mice Mice, Inbred C57BL Mice, Knockout Muscle, Skeletal Physical Conditioning, Animal Physical Exertion

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