Increased concentrations of glycogen synthase protein in skeletal
muscle of patients with niddm.
L[diaeresis]ofman, Monika, Hannele Yki-J[umlaut]arvinen, Maija
Parkkonen, Jaana Lindstr[diaeresis]om, Laslzo Koranyi, Camilla
Schalin-J[umlaut]antti, and Leif Groop.
Fourth Department of Medicine, Helsinki University Hospital, Second
Department of Medicine, Helsinki University Hospital, Department of
Biochemistry, Helsinki University, Helsinki, Finland, and Hungarian
Heart Centre, Balatonfuered, Hungary.
APStracts 2:0050E, 1995.
To examine whether changes in the glycogen synthase protein
concentration contributes to impaired insulin-stimulated glycogen
metabolism in patients with non-insulin dependent diabetes mellitus
(NIDDM), muscle biopsies were taken before and after a 4 h euglycemic
hyperinsulinemic clamp to measure glycogen synthase activity and
glycogen synthase protein concentrations in 14 patients with NIDDM
and in 17 control subjects. Non-oxidative glucose metabolism was
reduced by 64% in patients with NIDDM compared with control subjects,
and correlated with insulin-stimulated glycogen synthase activity (r
= 0.55, p<0.05). The concentration of glycogen synthase protein in
skeletal muscle was higher in patients with NIDDM than in control
subjects (6.75 +/- 0.88 vs. 4.41 +/- 0.50 cpm/[mu]g protein,
p<0.05), whereas there was no significant difference in glycogen
synthase mRNA concentration between the two groups. The glycogen
synthase protein concentration correlated inversely with the rate of
non-oxidative glucose metabolism (r = - 0.63, p<0.05). These
findings indicate that the amount of glycogen synthase protein is
increased in skeletal muscle of patients with NIDDM. The increase in
the glycogen synthase protein may serve to compensate for a
functional defect in the activation of the enzyme by insulin.
Received 30 November 1993; accepted in final form 9 January 1995.
APS Manuscript Number E472-3.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 28 March 1995.