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

Authors :
Shearer, Jane
Fueger, Patrick T.
Rottman, Jeffrey N. Bracy, Deanna P.
Binas, Bert
Wasserman, David H.
Source :
The American Journal of Physiology. Feb, 2005, Vol. 288 Issue 2, pE292, 6 p.
Publication Year :
2005

Abstract

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-FAB[P.sup.+/-], n = 8), and null (H-FAB[P.sup.-/-], 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 [[sup.125]I]-15-(p-iodophenyl)-3-R, S-methylpentadecanoic acid and 2-deoxy-[[sup.3]H]glucose was administered to obtain rates of whole body metabolic clearance (MCR) and indexes of muscle LCFA ([R.sub.f]) and glucose ([R.sub.g]) utilization. Fasting, nonesterified fatty acids (mM) were elevated in H-FAB[P.sup.-/-] mice (2.2 [+ or -] 0.9 vs. 1.3 [+ or -] 0.1 and 1.3 [+ or -] 0.2 for WT and H-FAB[P.sup.+/-]). During exercise, blood glucose (mM) increased in WT (11.7 [+ or -] 0.8) and H-FAB[P.sup.+/-] (12.6 [+ or -] 0.9) mice, whereas H-FAB[P.sup.-/-] mice developed overt hypoglycemia (4.8 [+ or -] 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.sub.f] and increasing [R.sub.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. skeletal muscle; metabolism; substrate balance; 2-deoxyglucose; 15-(p-iodophenyl)-3-R, S-methylpentadecanoic acid

Details

Language :
English
ISSN :
00029513
Volume :
288
Issue :
2
Database :
Gale General OneFile
Journal :
The American Journal of Physiology
Publication Type :
Academic Journal
Accession number :
edsgcl.128974939