The effect of a low dose of clenbuterol on rat soleus muscle submitted to joint immobilization

The aim of the present study was to evaluate the effect of joint immobilization on morphometric parameters and glycogen content of soleus muscle treated with clenbuterol. Male Wistar (3-4 months old) rats were divided into 4 groups (N = 6 for each group): control, clenbuterol, immobilized, and immobilized treated with clenbuterol. Immobilization was performed with acrylic resin orthoses and 10 µg/kg body weight clenbuterol was administered subcutaneously for 7 days. The following parameters were measured the next day on soleus muscle: weight, glycogen content, cross-sectional area, and connective tissue content. The clenbuterol group showed an increase in glycogen (81.6 percent, 0.38 ± 0.09 vs 0.69 ± 0.06 mg/100 g; P < 0.05) without alteration in weight, cross-sectional area or connective tissue compared with the control group. The immobilized group showed a reduction in muscle weight (34.2 percent, 123.5 ± 5.3 vs 81.3 ± 4.6 mg; P < 0.05), glycogen content (31.6 percent, 0.38 ± 0.09 vs 0.26 ± 0.05 mg/100 mg; P < 0.05) and cross-sectional area (44.1 percent, 2574.9 ± 560.2 vs 1438.1 ± 352.2 µm²; P < 0.05) and an increase in connective tissue (216.5 percent, 8.82 ± 3.55 vs 27.92 ± 5.36 percent; P < 0.05). However, the immobilized + clenbuterol group showed an increase in weight (15.9 percent; 81.3 ± 4.6 vs 94.2 ± 4.3 mg; P < 0.05), glycogen content (92.3 percent, 0.26 ± 0.05 vs 0.50 ± 0.17 mg/100 mg; P < 0.05), and cross-sectional area (19.9 percent, 1438.1 ± 352.2 vs 1724.8 ± 365.5 µm²; P < 0.05) and a reduction in connective tissue (52.2 percent, 27.92 ± 5.36 vs 13.34 ± 6.86 percent; P < 0.05). Statistical analysis was performed using Kolmogorov-Smirnov and homoscedasticity tests. For the muscle weight and muscle glycogen content, two-way ANOVA and the Tukey test were used. For the cross-sectional area and connective tissue content, Kruskal-Wallis and Tukey tests were used. This study emphasizes the importance of anabolic pharmacological...

Effects of insulin and exercise on glucose uptake of skeletal muscle in diabetic rats / 영남의대학술지

The effects of insulin and exercise on glucose uptake of skeletal muscle were investigated in soleus muscle isolated from low dose streptozotocin induced diabetic rat in vitro. Glucose uptake was assessed by measuring ³H-methylglucose uptake in vitro. Basal glucose uptake in diabetes was reduced by approximately one-third of the control value (5.6±0.73µMol/g/20min. in diabetes versus 8.4±0.77 in control, P<0.01). There was also a significant decrease (P<0.01) in glucose uptake of diabetes at physiologic insulin concentration (200 µIU/ml) by 40% (6.1±1.20 versus 10.0±0.81). Furthermore, maximal insulin (20000 µIU/ml)-stimulated glucose uptake was 36% lower in diabetes as compared with control (7.3±1.29 versus 11.4±1.29, P<0.01). In contrast, exercise (1.0 km/hr, treadmill running for 45 min.) effect on glucose uptake was so dramatic in diabetes that glucose uptake at basal state was 8.+1.09 and insulin stimulated-glucose uptake were 10.2±1.47 and 11.9±1.64, in 200 and 20000 µIU/ml added insulin, respectively. These results suggest that insulin insensitivity develops in skeletal muscle after 2 weeks of streptozotocin-induced diabetes, but these insensitivity was recovered significantly by single session of running exercise.