title: Assessment of transcapillary glucose exchange in human skeletal muscle and adipose tissue.
abstract: We studied the kinetics of glucose exchange between plasma and interstitial fluid (ISF) in human skeletal muscle and adipose tissue under fasting conditions. Five normal human subjects received an intravenous [6,6-2H2]glucose infusion in a prime-continuous fashion. During the tracer infusion, the open-flow microperfusion technique was employed to frequently sample ISF from quadriceps muscle and subcutaneous adipose tissue. The tracer glucose kinetics observed in muscle and adipose tissue ISF were found to be well described by a capillary-tissue exchange model. As a measure of transcapillary glucose exchange efficiency, the 95% equilibrium time was calculated from the identified model parameters. This time constant was similar for skeletal muscle and adipose tissue (28.6 +/- 3.2 vs. 26.8 +/- 3.6 min; P = 0.60). Furthermore, we found that the (total) interstitial glucose concentration was significantly lower (P < 0.01) in muscle (3.32 +/- 0.46 mmol/l) and adipose tissue (3.51 +/- 0.17 mmol/l) compared with arterialized plasma levels (5.56 +/- 0.13 mmol/l). Thus the observed gradients and dynamic relationships between plasma and ISF glucose in muscle and adipose tissue provide evidence that transcapillary exchange of glucose is limited in these two tissues under fasting conditions.
authors.affiliation: Dept. of Biophysics, Institute of Biomedical Engineering, Graz Univ. of Technology, Krenngasse 37, A-8010 Graz, Austria. werner.regittnig@healthgate.at
authors.forename: Werner
authors.initials: W
authors.lastname: Regittnig
authors.forename: Martin
authors.initials: M
authors.lastname: Ellmerer
authors.forename: Günter
authors.initials: G
authors.lastname: Fauler
authors.forename: Gerald
authors.initials: G
authors.lastname: Sendlhofer
authors.forename: Zlatko
authors.initials: Z
authors.lastname: Trajanoski
authors.forename: Hans-Jörg
authors.initials: HJ
authors.lastname: Leis
authors.forename: Lukas
authors.initials: L
authors.lastname: Schaupp
authors.forename: Paul
authors.initials: P
authors.lastname: Wach
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Pieber
mesh_terms: D000273:Adipose Tissue / Q000098:blood supply* / Q000737:chemistry; D000328:Adult; D001158:Arteries; D001786:Blood Glucose / Q000378:metabolism*; D015992:Body Mass Index; D002196:Capillaries; D003903:Deuterium; D005110:Extracellular Space / Q000378:metabolism; D005947:Glucose / Q000032:analysis / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D008297:Male; D008353:Mannitol / Q000008:administration & dosage / Q000032:analysis; D008433:Mathematics; D018482:Muscle, Skeletal / Q000098:blood supply* / Q000737:chemistry
chemical_list: D001786:Blood Glucose; D008353:Mannitol; D003903:Deuterium; D005947:Glucose