Section of Diabetic Complications
Role of nitric oxide synthase inhibitor in the skeletal muscle contractile dysfunction of type 2 diabetic rats
Li Xiaomei, Fu Sihai, Lei Yanping, Lin Yuan, Xiong Yan
Published 2017-10-20
Cite as J Chin Physician, 2017,19(10): 1462-1468. DOI: 10.3760/cma.j.issn.1008-1372.2017.10.004
Abstract
ObjectiveTo investigate the role of endogenous nitric oxide synthase (NOS) inhibitor asymmetric dimethylarginine (ADMA) in the contractile dysfunction of skeletal muscle in diabetic rats and on which the therapeutic effects of L-Arginine.
MethodsType 2 diabetic rats were induced by high fat diet and a single intraperitoneal injection of streptozotocin (STZ, 30 mg/kg), followed by high fat diet for 8 weeks. Specific twicth tension and specific tetanic tension of soleus (SOL) and extensor digitorum longus (EDL) isolated from control and diabetic rats were detected by electric stimulation to reflect contractile function of skeletal muscle. ADMA content of skeletal muscle was analyzed by enzyme linked immunosorbent assay (ELISA), and activities of dimethylarginie dimethylaminohydrolase (DDAH) and NOS, NO content were measured by colorimetry. The protein expression of ADMA synthetase protein arginine methyl transferase 1 (PRMT1) and ADMA hydrolase DDAH and NOS were determined detected by Western blott-ing. Oral glucose tolerance test and protein expressions of phosphorylated insulin receptor substrate 1(p-IRS-1) and protein kinase B (p-Akt) as well as the membrane transportation of glucose transporter 4 (Glut4) were measured to reflect insulin resistance.
ResultsIn comparison with control rats, specific twicth tension and tetanic tension of SOL and EDL in diabetic rats were significantly decreased (P<0.01), indicating the contractile dysfunction. Increased ADMA content (P<0.05), decreased DDAH and NOS activities as well as NO content (P<0.01) in comparison with up-regulated protein expression of PRMT1 and down-regulated protein expression of DDAH, endothelial NOS (eNOS) and neuronal NOS (nNOS)(P<0.05) were observed in the skeletal muscle of diabetic rats compared to control rats, indicating that the pathway of PRMT1/ADMA/DDAH/ NOS/NO was disordered in the skeletal muscle of diabetic rats. Furthermore, the glucose tolerance, both IRS-1 and Akt protein phosphorylation as well as the membrane translocation of Glut4 were decreased (P<0.05), indicating the insulin resistance in diabetic rats. Treatment with L-Arginine for 8 weeks not only significantly improved the contractile dysfunction but also reversed the disorder of ADMA signaling pathway and insulin resistance in skeletal muscle of diabetic rats compared to untreated diabetic rats.
ConclusionsThe accumulation of endogenous NOS inhibitor ADMA contributes to the contractile dysfunction of skeletal muscle in diabetic rats, the underlying mechanism may be related to insulin resistance.
Key words:
Asymmetric dimethylarginine; Type 2 diabetes mellitus; Contractile dysfunction; Insulin resistance; L-arginine
Contributor Information
Li Xiaomei
Guangzhou Institute of Snake Venom Research, School of Pharmaceutical Sciences, Guangzhou Medical University, Guangzhou 511436, China; Center of Medical Experiment, the Fifth Affiliated Hospital of Guangzhou Medical University, Guangzhou 510750, China
Fu Sihai
Guangzhou Institute of Snake Venom Research, School of Pharmaceutical Sciences, Guangzhou Medical University, Guangzhou 511436, China
Lei Yanping
Guangzhou Institute of Snake Venom Research, School of Pharmaceutical Sciences, Guangzhou Medical University, Guangzhou 511436, China
Lin Yuan
Guangzhou Institute of Snake Venom Research, School of Pharmaceutical Sciences, Guangzhou Medical University, Guangzhou 511436, China
Xiong Yan
Guangzhou Institute of Snake Venom Research, School of Pharmaceutical Sciences, Guangzhou Medical University, Guangzhou 511436, China; Center of Medical Experiment, the Fifth Affiliated Hospital of Guangzhou Medical University, Guangzhou 510750, China