Chinese Medicine, Jiang-Tang-Ke-Li, Improves Insulin Resistance by Modulating Muscle Fiber Composition and Muscle Tumor Necrosis Factor-.ALPHA. in Fructose-Fed Rats

Abstract

Insulin resistance and hyperinsulinemia are common findings in patients with essential hypertension. These impairments in glucose metabolism are commonly associated with diabetes mellitus, hypertension, and dyslipidemia, which are high risk factors of cardiovascular diseases, and recent evidence indicates that they may play a role in the development of coronary artery disease. The aim of this study was to determine the effect of Jiang-Tang-Ke-Li (JTKL), a traditional Chinese medicine used to treat diabetes mellitus in China, on insulin resistance and hypertension in fructose-fed rats (FFR). Systolic blood pressures in the FFR groups were significantly higher than that in the control group, although JTKL had no effect on systolic blood pressure for the last 2 weeks of treatment with the medicine. The average rate of glucose infusion during a glucose clamp, as an index of insulin sensitivity (M value), was significantly lower in the FFR than in the control rats, and treatment with JTKL for 2 weeks significantly increased the M value to that of the control. Treatment with Panax ginseng (PG), a component of JTKL, for 2 weeks also significantly increased the M value of FFR to the control level. The composite ratio of type I fibers in soleus muscle decreased significantly in the FFR compared to that in the control, and treatment with JTKL led to recovery of the composite ratio of type I fibers to the same level as that of the control group. The M value showed a significant positive correlation with the composite ratio of type I fibers and a significant negative correlation with the composite ratio of type II fibers. Tumor necrosis factor (TNF)-α levels were significantly higher in the soleus and extensor digitorum longus (EDL) muscles of the FFR than in those of the control rats. Treatment with JTKL for 2 weeks significantly lowered TNF-α levels to the control levels. M values showed a significant negative correlation with TNF-α in both the soleus and EDL muscles. The results suggest that the Chinese medicine JTKL, which contains PG as one of its valid components, improves insulin resistance by modulating muscle fiber composition and TNF-α in skeletal muscles in hypertensive and insulin-resistant FFR. (Hypertens Res 2003; 26: 527-532)