TY - JOUR
T1 - Sources of blood glycerol during fasting
AU - Jensen, Michael D.
AU - Chandramouli, Visvanathan
AU - Schumann, William C.
AU - Ekberg, Karin
AU - Previs, Stephen F.
AU - Gupta, Sameer
AU - Landau, Bernard R.
PY - 2001
Y1 - 2001
N2 - To determine the source(s) of blood and very low density lipoprotein (VLDL)-triglyceride glycerol during fasting, four men ingested 2H2O from 14 to 20 h into a 60-h fast to achieve ∼0.5% body water enrichment. At 60 h of fasting, glycerol flux was measured using [2-14C]glycerol. Blood was taken for measurement of 2H enrichment at carbon 6 of glucose and at carbon 3 of free glycerol and VLDL-triglyceride glycerol. 2H enrichment of the 2 hydrogens bound to carbon 3 of VLDL-triglyceride glycerol was 105 ± 2% of the 2H enrichment of the 2 hydrogens bound to carbon 6 of glucose, indicating isotopic equilibrium between hepatic glyceraldehyde 3-P and glycerol 3-P. The 2H enrichment of the 2 hydrogens bound to carbon 3 of free glycerol was 17 ± 3% of VLDL-triglyceride glycerol, indicating that a significant percentage of free glycerol in blood originated from the hydrolysis of circulating VLDL-triglyceride or a pool of glycerol with similar 2H enrichment. Glycerol flux was 6.3 ± 1.1 μmol·kg-1·min-1. Glycerol appearing from nonadipose tissue sources was then ∼1.1 μmol·kg-1·min-1. Seven other subjects were fasted for 12, 42, and 60 h. A small percentage of glycerol in the circulation after 12 h of fasting was enriched with 2H. The enrichment of the 2 hydrogens bound to carbon 3 of free glycerol in the longer periods of fasting was ∼16% of the enrichment of the 2 hydrogens bound to carbon 6 of glucose. Therefore, as much as 15-20% of systemic glycerol turnover during fasting is not from lipolysis of adipose tissue triglyceride.
AB - To determine the source(s) of blood and very low density lipoprotein (VLDL)-triglyceride glycerol during fasting, four men ingested 2H2O from 14 to 20 h into a 60-h fast to achieve ∼0.5% body water enrichment. At 60 h of fasting, glycerol flux was measured using [2-14C]glycerol. Blood was taken for measurement of 2H enrichment at carbon 6 of glucose and at carbon 3 of free glycerol and VLDL-triglyceride glycerol. 2H enrichment of the 2 hydrogens bound to carbon 3 of VLDL-triglyceride glycerol was 105 ± 2% of the 2H enrichment of the 2 hydrogens bound to carbon 6 of glucose, indicating isotopic equilibrium between hepatic glyceraldehyde 3-P and glycerol 3-P. The 2H enrichment of the 2 hydrogens bound to carbon 3 of free glycerol was 17 ± 3% of VLDL-triglyceride glycerol, indicating that a significant percentage of free glycerol in blood originated from the hydrolysis of circulating VLDL-triglyceride or a pool of glycerol with similar 2H enrichment. Glycerol flux was 6.3 ± 1.1 μmol·kg-1·min-1. Glycerol appearing from nonadipose tissue sources was then ∼1.1 μmol·kg-1·min-1. Seven other subjects were fasted for 12, 42, and 60 h. A small percentage of glycerol in the circulation after 12 h of fasting was enriched with 2H. The enrichment of the 2 hydrogens bound to carbon 3 of free glycerol in the longer periods of fasting was ∼16% of the enrichment of the 2 hydrogens bound to carbon 6 of glucose. Therefore, as much as 15-20% of systemic glycerol turnover during fasting is not from lipolysis of adipose tissue triglyceride.
KW - Deuterated water
KW - Lipolysis
KW - Triglyceride
KW - Very low density lipoprotein
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U2 - 10.1152/ajpendo.2001.281.5.e998
DO - 10.1152/ajpendo.2001.281.5.e998
M3 - Article
C2 - 11595656
AN - SCOPUS:0035195582
SN - 0193-1849
VL - 281
SP - E998-E1004
JO - American Journal of Physiology - Endocrinology and Metabolism
JF - American Journal of Physiology - Endocrinology and Metabolism
IS - 5 44-5
ER -