A novel method to assess intracellular glucose concentration in
muscle, in vivo..
Cline, Gary W., Beat M. Jucker, Zlatko Trajanoski, Alexander J. M.
Rennings, Gerald I Shulman.
Department of Internal Medicine, Yale University School of
Medicine, New Haven, CT. University Hospital Leiden, Department of
Internal Medicine, Section of Endocrinology, Leiden, The
Netherlands.
APStracts 4:0267E, 1997.
Intracellular glucose concentration in skeletal muscle of awake rats
was determined under conditions of hyperglycemic (10.2+/-0.6mM)
-hyperinsulinemia (1200 pM) and hyperglycemic (20.8+/-1.5mM)
-hypoinsulinemia (<12 pM) using 13C-NMR spectroscopy, during a
prime-constant infusion of [1-13C]glucose and [1-13C]mannitol, with
either insulin (10 mU/kg/min), or somatostatin (1.0 [mu]g/kg/min).
Intracellular glucose was calculated as the difference between the
concentrations of total tissue glucose (calculated from the in vivo
13C-NMR spectrum using mannitol as an internal concentration
standard) and extracellular glucose, corrected by the ratio of intra-
and extracellular water space. Extracellular concentration was
corrected for an interstitial fluid to plasma glucose concentration
gradient of 0.83+/-0.07, determined by open flow microperfusion. The
mean ratio of intra- to extracellular glucose space, determined from
the relative NMR signal intensities and concentrations of mannitol
and total creatine, was 9.2+/-1.1 (hyperglycemic-hyperinsulinemia,
n=10), and 9.0+/-1.7 ( hyperglycemic-hypoinsulinemia, n=7). Mean
muscle intracellular glucose concentration was -0.09+/-0.10 mM under
hyperglycemic-hyperinsulinemic conditions (n=10), and 0.32+/-0.06 mM
under hyperglycemic-hypoinsulinemic conditions (n=7). This method is
noninvasive and should prove useful for resolving the question of
whether glucose transport or phosphorylation is responsible for the
reduced rate of muscle glycogen synthesis observed in diabetic
subjects.
Received 26 August 1997; accepted in final form 17 November 1997.
APS Manuscript Number E397-7.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1997 The American Physiological Society.
Published in APStracts on 12 December 1997