Glycerol production and utilization in humans: sites and quantitation.
Liver is assumed to be the major site of glycerol uptake and fatty acid reesterification. [U-13C]glycerol was infused into ten 60 h-fasted healthy subjects. Measured were 1) blood glycerol concentrations and 13C enrichments in brachial and pulmonary arteries and in hepatic, renal, superficial, and deep forearm veins; 2) glycerol appearance rates in systemic circulation; and 3) splanchnic bed and kidney glycerol uptakes with use of balance and tracer methodology. Glycerol concentrations were one-fifth in hepatic, one-half in renal, 40% more in superficial, and the same in deep vein and pulmonary artery as in brachial artery blood. Glycerol enrichments were one-fifth in hepatic, two-thirds to three-quarters in renal and superficial veins, and the same in pulmonary as in brachial artery blood. Splanchnic glycerol uptake was 29% and kidney glycerol uptake was 17% of glycerol's rate of appearance, 5.11 mumol.min-1.kg-1. Splanchnic fatty acid uptake was 25% of calculated fatty acid release. Glycerol contributed 15% to glucose production. Most of the [13C]glycerol uptake by splanchnic bed and kidneys was incorporated into glucose. Thus, in 60 h-fasted individuals, most glycerol uptake does not occur in liver, and the extent of fatty acid reesterification in liver is in doubt.
Landau
B R
BR
Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, USA.
Wahren
J
J
Previs
S F
SF
Ekberg
K
K
Chandramouli
V
V
Brunengraber
H
H
D000328:Adult; D001835:Body Weight; D005990:Glycerol / Q000378:metabolism*; D006801:Humans; D008297:Male; D009928:Organ Specificity; D012039:Regional Blood Flow
D005990:Glycerol