Hyperglycemia induces accumulation of glucose in human skeletal muscle.
The effect of hyperglycemia on whole body substrate utilization and the metabolic profile of skeletal muscle has been investigated. Eight glucose-tolerant men were infused with somatostatin (S) for 190 min. During the last 120 min of S infusion, glucose was infused to achieve a steady-state plasma level of 26 mmol/l. Biopsies were obtained from the quadriceps femoris muscle immediately before and 35 and 120 min after induction of hyperglycemia. Steady-state glucose disposal during hyperglycemia averaged (+/- SE) 33.8 +/- 3.2 mumol.kg fat-free mass-1.min-1, and approximately 70% of the glucose disposal was accounted for by skeletal muscle. Intracellular glucose increased from 0.9 +/- 0.2 mmol/kg dry wt during S to 9.5 +/- 2.5 during hyperglycemia (P less than 0.01). It was estimated that approximately 35% of the glucose taken up by muscle during 120 min of hyperglycemia was not phosphorylated. Muscle contents of alpha-D-glucose 1,6-diphosphate, D-glucose 6-phosphate, ATP, ADP, and AMP (both of which are based on the phosphocreatine-to-creatine ratio), which have been shown to inhibit hexokinase in vitro, did not change significantly during hyperglycemia, nor were there any significant changes in any of the other postphosphofructokinase intermediates, D-fructose 2,6-diphosphate, and citrate. Hyperglycemia did not alter the fractional activities of glycogen synthase or phosphorylase, nor total phosphorylase activity. However, hyperglycemia resulted in a 55% increase in glycogen synthase-specific activity (P less than 0.01). It is concluded that hyperglycemia results in a marked increase in muscle glucose.(ABSTRACT TRUNCATED AT 250 WORDS)
Katz
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A
Department of Kinesiology, University of Illinois, Urbana 61801.
Raz
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Spencer
M K
MK
Rising
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R
Mott
D M
DM
D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005947:Glucose / Q000378:metabolism*; D005958:Glucosephosphates / Q000378:metabolism; D006006:Glycogen Synthase / Q000378:metabolism; D006801:Humans; D006943:Hyperglycemia / Q000378:metabolism*; D007328:Insulin / Q000097:blood; D007700:Kinetics; D008297:Male; D009132:Muscles / Q000378:metabolism*; D010710:Phosphates / Q000378:metabolism; D006005:Phosphorylases / Q000378:metabolism; D013004:Somatostatin / Q000494:pharmacology
D001786:Blood Glucose; D005230:Fatty Acids, Nonesterified; D005958:Glucosephosphates; D007328:Insulin; D010710:Phosphates; D013004:Somatostatin; C031590:glucose-1-phosphate; D006005:Phosphorylases; D006006:Glycogen Synthase; D005947:Glucose