A multicompartmental model of in vivo adipose tissue glycerol kinetics and capillary permeability in lean and obese humans

Simon W. Coppack, David L. Chinkes, John M. Miles, Bruce W. Patterson, Samuel Klein

Research output: Contribution to journalArticle

13 Scopus citations

Abstract

Lipolysis of adipose tissue triglycerides releases glycerol. Twenty-four volunteers, of whom 6 were obese and 13 were women, received a primed-constant infusion of 2H5-glycerol for 120 min during postabsorptive steady-state conditions. Arterial, abdominal venous, and interstitial (microdialysis) samples were taken, and a four-compartment model was applied to assess subcutaneous abdominal adipose tissue glycerol kinetics. Adipose tissue blood flow was measured using 133Xe washout. Venous glycerol concentrations (median 230 μmol/l [interquartile range 210-268]) were consistently greater than those of arterial blood (69.1 μmol/l [56.5-85.5]), while glycerol isotopic enrichments (tracer-to-tracee ratio) were greater in arterial blood (8.34% [7.44-10.1]) than venous blood (2.34% [1.71-2.69], P < 0.01). Microdialysate glycerol enrichment was 1.44% (1.11-1.79), indicating incomplete permeability of glycerol between capillary blood and interstitium. Calculated interstitial glycerol concentrations were between 270 μmol/l (256-350) and 332 μmol/l (281-371) (examining different boundary conditions). The calculated capillary diffusion capacity (ps) was between 2.21 ml · 100 g tissue-1 · min-1 (1.31-3.13) and 3.09 ml · 100 g tissue-1 · min-1 (1.52-4.90) and correlated inversely with adiposity (Rs ≤ -0.45, P < 0.05). Our results support previous estimates of interstitial glycerol concentration within adipose tissue and reveal capillary diffusion capacity is reduced in obesity.

Original languageEnglish
Pages (from-to)1934-1941
Number of pages8
JournalDiabetes
Volume54
Issue number7
DOIs
StatePublished - Jul 1 2005

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