Fig. 9.

Fractional 2[³H]DG uptake in gastrocnemius of mice expressing 0, 0.5, 1.0 and ∼3.5 fold WT GLUT4 levels during the steady state period of a 4.0 mU·kg⁻¹·min⁻¹ insulin clamp or during an equal duration saline infusion (top). The same comparisons are made for sedentary (Sed) and exercised mice (bottom). HK II content was either normal (WT) or the protein was overexpressed. GLUT4 only affected fractional 2[³H]DG uptake during saline infusion when it was overexpressed. On the other hand, the absence of GLUT4 caused a marked attenuation of fractional 2[³H]DG uptake during insulin stimulation regardless of whether HK II was overexpressed. HK II overexpression had no effect on the response during saline infusion but increased the maximal response to insulin. Each point is means ± SE for 8–11 in vivo mouse experiments. Data are from Fueger and colleagues (25, 31).