ABSTRACT
<p><b>OBJECTIVE</b>To study the effects of Compound Danshen Dripping Pill (CDDP) on the structure and functions of sternohyoid muscle in metabolic syndrome (MS) rats, and to study whether it has therapeutic effects on obstructive sleep apnea-hypopnea syndrome (OSAHS).</p><p><b>METHODS</b>Twenty-one healthy male SD rats were randomly divided into three groups, i.e., the normal control group (n = 6), the MS group (n = 8), and the CDDP group (n = 7). Rats in the normal control group were routinely fed. High lipid forage was given to rats in the rest two groups. Nine weeks later, CDDP (at the dose of 375 mg/kg) was additionally given to rats in the CDDP group by gastrogavage, and then rats in the CDDP group and the MS group were fed with the same high lipid forage for 12 successive weeks. The content of malondialdehyde (MDA) and the activities of superoxide dismutase (SOD) in the sternohyoid muscle were detected in the three groups. The capillary density, capillary-to-fiber ratio (C/F), the section area of type I muscle fiber were detected using myosin-ATPase histochemical assay. The contractile changes of isometric stemohyoid muscles were determined under electric stimulation by different frequencies.</p><p><b>RESULTS</b>The contents of MDA were obviously lower in the CDDP group than in the MS group, while the activities of SOD, the capillary density, C/F, the section area of type I muscle fiber, the tension of stemohyoid muscle at 10 -60 Hz, and the 1-5 min tension percentages of the stemohyoid muscle were higher in the CDDP group than in the MS group (P < 0.05, P < 0.01).</p><p><b>CONCLUSION</b>CDDP could improve oxidative stress induced intramuscularly microcirculation disturbance and changes of muscular fiber structures of the upper airway muscles, and elevate their contractile functions, thus possibly contributing to favorable effects on OSAHS.</p>