Fig. 1

Heat stimulation in vivo facilitates muscle glucose uptake in vivo and in vitro. Under anesthesia, the hindlimbs of rats weighing ~250 and ~60 g were immersed for 30 min in temperature-controlled water set at either 36 or 42 °C. For measurement of the in vivo thermal effect on muscle glucose uptake in vivo (b), 2-deoxyglucose (2DG) was injected to rats weighing ~250 g through a cannula 10 min before the end of heat stimulation. Immediately after the cessation of heat stimulation, the temperatures of extensor digitorum longus (EDL) and soleus muscles were measured in situ (a), and then both muscles were snap-frozen. For measurement of the in vivo thermal effect on muscle glucose uptake in vitro (d), the temperatures of EDL and soleus muscles of rats weighing ~60 g were measured in situ immediately after the cessation of heat stimulation (c), and then both muscles were removed and were incubated with 2DG for 10 min at 36 °C. Data are expressed as the mean ± SE (n = 3 for a, n = 6 for b, n = 4–5 for c, n = 6 for d). ^# p < 0.05 as compared to the control (36 °C). Temp temperature