Oral administration of glucose promotes intracellular partitioning of fatty acid toward storage in white but not in red muscle.
Lipid accumulation in non-adipose tissues is strongly associated with the metabolic syndrome, possibly due to aberrant partitioning of intracellular fatty acids between storage and oxidation. In the present study, we administered the non-metabolizable fatty acid analog [9,10-(3)H]-(R)-2-bromopalmitate, and authentic (14)C-palmitate to conscious rats, in order to directly examine the initial intracellular fate of fatty acids in a range of insulin-sensitive tissues, including white and red muscles, liver, white adipose tissue, and heart. Rats were studied after administration of an oral glucose load to examine the effect of physiological elevation of glucose and insulin. The tracer results showed that glucose administration partitioned fatty acid toward storage in white muscle (storage:uptake ratios, vehicle vs glucose; 0.64 +/- 0.02 vs 0.92 +/- 0.09, P < 0.05), and in liver (0.66 +/- 0.07 vs 0.98 +/- 0.04, P < 0.05), but not in red muscle (1.18 +/- 0.07 vs 1.36 +/- 0.11, P = not significant). These results demonstrate the physiological relevance of the so-called 'reverse' Randle cycle, but surprisingly show that it may be more important in white rather than oxidative red muscle.
Fosgerau
Keld
K
In vivo Pharmacology, Rheoscience, Ledøje Bygade 23B, DK-2765 Ledøje-Smørum, Denmark. kf@rheoscience.com
Fledelius
Christian
C
Pedersen
Kent E
KE
Kristensen
Jesper B
JB
Daugaard
Jens R
JR
Iglesias
Miguel A
MA
Kraegen
Edward W
EW
Furler
Stuart M
SM
D000273:Adipose Tissue / Q000378:metabolism; D000284:Administration, Oral; D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D002247:Carbon Isotopes; D005227:Fatty Acids / Q000378:metabolism*; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005947:Glucose / Q000008:administration & dosage*; D005951:Glucose Tolerance Test; D005990:Glycerol / Q000097:blood; D007328:Insulin / Q000378:metabolism; D007333:Insulin Resistance; D050356:Lipid Metabolism; D008099:Liver / Q000378:metabolism; D008297:Male; D008657:Metabolic Clearance Rate; D018656:Muscle Fibers, Fast-Twitch / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism; D010084:Oxidation-Reduction; D010168:Palmitates / Q000008:administration & dosage / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley
D001786:Blood Glucose; D002247:Carbon Isotopes; D005227:Fatty Acids; D005230:Fatty Acids, Nonesterified; D007328:Insulin; D010168:Palmitates; D005947:Glucose; D005990:Glycerol