Blood glycerol is an important precursor for intramuscular triacylglycerol synthesis

Zeng Kui Guo, Michael D. Jensen

Research output: Contribution to journalArticle

69 Scopus citations

Abstract

The utilization of blood glycerol and glucose as precursors for intramuscular triglyceride synthesis was examined in rats using an intravenous infusion of [2-14C]g-lycerol and [6-3H]glucose or [6- 14C]glucose. In 24-h fasted rats, more glycerol than glucose was incorporated into intramuscular triglyceride glycerol in soleus (69 ± 23 versus 4 ± 1 nmol/μmol triglyceride/h, respectively, p = 0.02 glycerol versus glucose) and in gastrocnemius (25 ± 5 versus 9 ± 2 nmol/μmol triglyceride/h, respectively, p = 0.02). Blood glucose was utilized more than blood glycerol for triglyceride glycerol synthesis in quadriceps. In fed rats, the blood glycerol incorporation rates (4 ± 2, 8 ± 3, and 9 ± 3 nmol/μmol triglyceride/h) were similar (p > 0.3) to those of glucose (5 ± 2, 9 ± 2, and 5 ± 2 nmol/μmol triglyceride/h for quadriceps, gastrocnemius, and soleus muscle, respectively). Glucose incorporation into intramuscular triglycerides was less with [6-3H]glucose than with [6- 14C]glucose, suggesting an indirect pathway for glucose carbon entry into muscle triglyceride. The isotopic equilibrium between plasma and intramuscular free glycerol ([U-13C]glycerol) was complete in quadriceps and gastrocnemius, but not soleus, within 2 h after beginning the tracer infusion. We conclude that blood glycerol is a direct and important precursor for muscle triglyceride synthesis in rats, confirming the presence of functionally important amounts of glycerol kinase in skeletal muscle.

Original languageEnglish (US)
Pages (from-to)23702-23706
Number of pages5
JournalJournal of Biological Chemistry
Volume274
Issue number34
DOIs
StatePublished - Aug 20 1999

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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