The synthetic rate of muscle triglyceride but not phospholipid is increased in obese rabbits

Xiao jun Zhang, David L. Chinkes, Zhanpin Wu, David Herndon, Robert R. Wolfe

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

Fat is a major energy source for skeletal muscle, and disruption of normal trafficking of fatty acids in muscle is linked to insulin resistance. We quantified muscle triglyceride (TG) and phospholipid (PL) synthesis in lean and obese rabbits by means of l-[U-13C16]palmitate infusion. Intramyocellular palmitoyl-coenzyme A was used as the precursor for rates of TG and PL synthesis, which were compared with the rates calculated using plasma nonesterified palmitate as the precursor. The muscle of obese rabbits had a greater (P < .05) combined pool of fatty acyl-coenzyme A plus fatty acyl-carnitine than lean rabbits (40.9 ± 3.7 vs 28.6 ± 5.3 nmol/g). Although the fractional synthetic rates of muscle TG were almost identical (0.095%/h ± 0.016%/h vs 0.092%/h ± 0.019%/h), the absolute synthetic rates were greater (P < .01) in the obese than in lean rabbits (39.7 ± 9.5 vs 10.1 ± 2.5 nmol g-1 h-1) because of greater TG content in the muscle of obese rabbits. Plasma nonesterified fatty acids and TG accounted for 51% to 55% of the true precursor pool for muscle lipid synthesis in both groups, and the rest was derived from fatty acids recycled within the muscle. In contrast, the fractional and absolute synthetic rates of muscle PL as well as PL contents were comparable in the 2 groups. In conclusion, the content and synthetic rate of muscle TG rather than PL were increased in obese rabbits, which might be linked to insulin resistance. Plasma lipids and muscle lipolysis were the 2 predominate contributors to the intramyocellular fatty acyl-coenzyme A pool for lipid synthesis.

Original languageEnglish (US)
Pages (from-to)1649-1656
Number of pages8
JournalMetabolism: Clinical and Experimental
Volume58
Issue number11
DOIs
StatePublished - Nov 2009

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Phospholipids
Triglycerides
Rabbits
Muscles
Acyl Coenzyme A
Palmitates
Lipids
Insulin Resistance
Fatty Acids
Palmitoyl Coenzyme A
Carnitine
Lipolysis
Nonesterified Fatty Acids
Skeletal Muscle
Fats

ASJC Scopus subject areas

  • Endocrinology
  • Endocrinology, Diabetes and Metabolism

Cite this

The synthetic rate of muscle triglyceride but not phospholipid is increased in obese rabbits. / Zhang, Xiao jun; Chinkes, David L.; Wu, Zhanpin; Herndon, David; Wolfe, Robert R.

In: Metabolism: Clinical and Experimental, Vol. 58, No. 11, 11.2009, p. 1649-1656.

Research output: Contribution to journalArticle

Zhang, Xiao jun ; Chinkes, David L. ; Wu, Zhanpin ; Herndon, David ; Wolfe, Robert R. / The synthetic rate of muscle triglyceride but not phospholipid is increased in obese rabbits. In: Metabolism: Clinical and Experimental. 2009 ; Vol. 58, No. 11. pp. 1649-1656.
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AB - Fat is a major energy source for skeletal muscle, and disruption of normal trafficking of fatty acids in muscle is linked to insulin resistance. We quantified muscle triglyceride (TG) and phospholipid (PL) synthesis in lean and obese rabbits by means of l-[U-13C16]palmitate infusion. Intramyocellular palmitoyl-coenzyme A was used as the precursor for rates of TG and PL synthesis, which were compared with the rates calculated using plasma nonesterified palmitate as the precursor. The muscle of obese rabbits had a greater (P < .05) combined pool of fatty acyl-coenzyme A plus fatty acyl-carnitine than lean rabbits (40.9 ± 3.7 vs 28.6 ± 5.3 nmol/g). Although the fractional synthetic rates of muscle TG were almost identical (0.095%/h ± 0.016%/h vs 0.092%/h ± 0.019%/h), the absolute synthetic rates were greater (P < .01) in the obese than in lean rabbits (39.7 ± 9.5 vs 10.1 ± 2.5 nmol g-1 h-1) because of greater TG content in the muscle of obese rabbits. Plasma nonesterified fatty acids and TG accounted for 51% to 55% of the true precursor pool for muscle lipid synthesis in both groups, and the rest was derived from fatty acids recycled within the muscle. In contrast, the fractional and absolute synthetic rates of muscle PL as well as PL contents were comparable in the 2 groups. In conclusion, the content and synthetic rate of muscle TG rather than PL were increased in obese rabbits, which might be linked to insulin resistance. Plasma lipids and muscle lipolysis were the 2 predominate contributors to the intramyocellular fatty acyl-coenzyme A pool for lipid synthesis.

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