Subcellular distribution of GLUT 4 in the skeletal muscle of lean type 2 (non-insulin-dependent) diabetic patients in the basal state

Abstract

Insulin resistance of the skeletal muscle is a key feature of Type 2 (non-insulin-dependent) diabetes mellitus. To determine whether a decrease of glucose carrier proteins or an altered subcellular distribution of glucose transporters might contribute to the pathogenesis of the insulin resistant state, we measured glucose transporter numbers in membrane fractions of gastrocnemius muscle of 14 Type 2 diabetic patients and 16 non-diabetic control subjects under basal conditions. Cytochalasin-B binding and immunoblotting with antibodies against transporter-subtypes GLUT 1 and GLUT 4 were applied. The cytochalasin-B binding values (pmol binding sites/g muscle) found in a plasma membrane enriched fraction, high and low density membranes of both groups (diabetic patients and non-diabetic control subjects) suggested a reduced number of glucose transporters in the plasma membranes of the diabetic patients compared to the control subjects (diabetic patients: 1.47 +/- 1.01, control subjects: 3.61 +/- 2.29, p less than or equal to 0.003). There was no clear difference in cytochalasin-B binding sites in high and low density membranes of both groups (diabetic patients: high density membranes 3.76 +/- 1.82, low density membranes: 1.67 +/- 0.81; control subjects: high density membranes 5.09 +/- 1.68, low density membranes 1.45 +/- 0.90). By Western blotting analysis we determined the distribution of the glucose transporter subtypes GLUT 1 and GLUT 4 in the plasma membrane enriched fraction and low density membranes of seven patients of each group.(ABSTRACT TRUNCATED AT 250 WORDS)