Diabetes, Vol 36, Issue 11 1292-1296, Copyright © 1987 by American Diabetes Association
Direct effects of sulfonylurea agents on glucose transport in the BC3H-1 myocyte
BJ Rogers, ML Standaert and RJ Pollet
Department of Medicine, University of South Florida, Tampa.
The actions of sulfonylurea agents to increase peripheral glucose disposal
have been classically ascribed to an ability to potentiate insulin action.
However, in the BC3H-1 cultured muscle cell, tolbutamide, glipizide, and
glyburide directly provoked more than a twofold increase in 2-deoxyglucose
(2-DG) uptake in a dose-dependent manner in the absence of insulin.
Tolbutamide (3 mM) enhanced 2-DG uptake by 130% in the presence or absence
of insulin and did not significantly change insulin binding or the
sensitivity of the insulin response. The onset of tolbutamide-stimulated
hexose transport was seen after 30 min and reached a plateau after 12 h.
Tolbutamide-stimulated glucose transport was associated with a twofold
increase in the Vmax of 2-DG uptake and was completely blocked by 50 microM
cytochalasin B, indicating that this action is mediated by increase in cell
membrane glucose transporters. We show that sulfonylureas at therapeutic
concentrations directly increase glucose transport into muscle cells.
Because muscle is the major peripheral target tissue for glucose disposal,
these results provide the basis for the therapeutic effect of these agents
in improving peripheral glucose disposal in insulin-resistant type II
(non-insulin-dependent) diabetes mellitus.