Soluble dietary fibre improves insulin sensitivity by increasing muscle GLUT-4 content in stroke-prone spontaneously hypertensive rats

1. The effects of soluble dietary fibre (psyllium) on peripheral insulin se nsitivity and skeletal muscle GLUT-4 protein expression were studied in 12 male stroke-prone spontaneously hypertensive rats (SHRSP) fed a high-calori c diet from 5 to 9 weeks of age. 2. In the psyllium-supplemented group, fasting plasma glucose was significa ntly reduced and glucose levels following an oral glucose tolerance test we re significantly lower than in the cellulose-supplemented group at 30 (P < 0.05) and 60 min (P < 0.01). However, there was no difference in insulin se cretion. 3, In the psyllium-supplemented group skeletal muscle LUT-4 content was sig nificantly increased in the plasma membrane (P < 0.001), but not in the int racellular membrane. 4. No significant difference was found in phosphatidylinositol 3 (PI3)-kina se activity between cellulose and psyllium diet not only in the basal state but also when stimulated by insulin. 5. These results demonstrate that psyllium increases blood glucose disposal by increasing skeletal muscle plasma membrane GLUT-4 content without PI3-k inase activation.