Assessment of transcapillary glucose exchange in human skeletal muscle and adipose tissue.
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.
Regittnig
Werner
W
Dept. of Biophysics, Institute of Biomedical Engineering, Graz Univ. of Technology, Krenngasse 37, A-8010 Graz, Austria. werner.regittnig@healthgate.at
Ellmerer
Martin
M
Fauler
Günter
G
Sendlhofer
Gerald
G
Trajanoski
Zlatko
Z
Leis
Hans-Jörg
HJ
Schaupp
Lukas
L
Wach
Paul
P
Pieber
Thomas R
TR
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
D001786:Blood Glucose; D008353:Mannitol; D003903:Deuterium; D005947:Glucose