Blood glycerol is an important precursor for intramuscular triacylglycerol synthesis

被引:75
作者
Guo, ZK [1 ]
Jensen, MD [1 ]
机构
[1] Mayo Clin, Endocrine Res Unit, Rochester, MN 55905 USA
关键词
D O I
10.1074/jbc.274.34.23702
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
The utilization of blood glycerol and glucose as precursors for intramuscular triglyceride synthesis was examined in rats using an intravenous infusion of [2-C-14]glycerol and [6-H-3]glucose or [6-C-14]glucose. In 24-h fasted rats, more glycerol than glucose was incorporated into intramuscular triglyceride glycerol in soleus (69 +/- 23 versus 4 +/- 1 nmol/mu mol triglyceride/h, respectively, p = 0.02 glycerol versus glucose) and in gastrocnemius (25 +/- 5 versus 9 +/- 2 nmol/mu mol 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/mu mol triglyceride/h) were similar (p > 0.3) to those of glucose (5 +/- 2, 8 +/- 2, and 5 +/- 2 nmol/mu mol triglyceride/h for quadriceps, gastrocnemius, and soleus muscle, respectively). Glucose incorporation into intramuscular triglycerides was less with [6-H-3]glucose than with [6-C-14]glucose, suggesting an indirect pathway for glucose carbon entry into muscle triglyceride. The isotopic equilibrium between plasma and intramuscular free glycerol ([U-C-13]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.
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页码:23702 / 23706
页数:5
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