Effect of glimepiride on insulin-stimulated glycogen synthesis in cultured human skeletal muscle cells: a comparison to glibenclamide.
OBJECTIVE
To examine the effect of glimepiride on insulin-stimulated glycogen synthesis in cultured human skeletal muscle cells in comparison with glibenclamide.


METHODS
Myotubes derived from glucose-tolerant subjects were incubated with glimepiride or glibenclamide (0-100 micro mol/l) for 4 h and with or without insulin (100 nmol/l) for 2 h, and subsequently glycogen synthesis was determined.


RESULTS
Glimepiride had no significant effect on basal glycogen synthesis; in contrast, glimepiride caused a dose-dependent increase of insulin-stimulated glycogen synthesis, with a maximal effect of 39.97 +/- 8.4% (mean +/- SEM, n = 4, P < 0,02). The time course of this glimepiride effect on insulin-stimulated glycogen synthesis showed a peak after 12 h incubation with a half maximal effect after 4 h. Preincubation of the myotubes with wortmannin (100 nmol/l), an inhibitor of phosphatidylinositol (PI)- 3 kinase, caused an inhibition of this glimepiride effect on insulin-stimulated glycogen synthesis. In contrast to glimepiride, incubation of myotubes with glibenclamide (0-100nmol/l), a second generation sulfonylurea, had no significant effect on basal or insulin-stimulated glycogen synthesis.


CONCLUSIONS
Incubation of cultured human skeletal muscle cells derived from glucose-tolerant subjects with glimepiride caused a dose-dependent increase of insulin-stimulated glycogen synthesis using therapeutic glimepiride concentrations. This glimepiride effect seems to be mediated via the PI3 kinase pathway. In contrast to glimepiride, glibenclamide had no significant effect on basal or insulin-stimulated glycogen synthesis. These results suggest that glimepiride, beside its well-known effect to stimulate insulin secretion, possess an insulin-sensitizing action in cultured human skeletal muscle cells in support of the concept of an extrapancreatic action of glimepiride.
Haupt
Axel
A
University of Tübingen, Department of Endocrinology and Metabolism, Germany.
Kausch
Christiana
C
Dahl
Dominik
D
Bachmann
Oliver
O
Stumvoll
Michael
M
Häring
Hans-U
HU
Matthaei
Stephan
S
D000730:Androstadienes / Q000494:pharmacology; D018929:Cell Culture Techniques / Q000379:methods; D002478:Cells, Cultured; D003924:Diabetes Mellitus, Type 2 / Q000235:genetics; D005260:Female; D005905:Glyburide / Q000494:pharmacology*; D006003:Glycogen / Q000096:biosynthesis*; D006801:Humans; D007004:Hypoglycemic Agents / Q000494:pharmacology*; D007328:Insulin / Q000494:pharmacology; D007700:Kinetics; D008297:Male; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism*; D013453:Sulfonylurea Compounds / Q000494:pharmacology*; D000077191:Wortmannin
D000730:Androstadienes; D007004:Hypoglycemic Agents; D007328:Insulin; D013453:Sulfonylurea Compounds; C057619:glimepiride; D006003:Glycogen; D005905:Glyburide; D000077191:Wortmannin