Effect of salvianolic acid A on vascular reactivity of streptozotocin-induced diabetic rats

The present study aims to evaluate the beneficial effect of salvianolic acid A (SAA) on the alterations in vascular reactivity of streptozotocin (STZ)-induced diabetic rats. Diabetes was induced by a single intraperitoneal injection of STZ (60 mg/kg). Following 16 weeks of SAA treatment (1 mg/kg/day), thoracic aortic rings of rats were mounted in organ baths. Contractile responses to noradrenaline (NA) and KCl and relaxant responses to acetylcholine (ACh) and sodium nitroprusside (SNP) were assessed. Loss of weight, hyperglycemia, elevated content of malondialdehyde (MDA) and decline of total antioxidant capacity (TAC) were observed in diabetic rats. SAA could reverse these metabolic and biochemical abnormalities. Compared to the control, the maximum contraction (Emax) to NA, but not sensitivity (pD2), increased significantly in diabetic aortas, which was prevented by SAA treatment. However, the response of rat aortas to KCl (Emax and pD2) was not altered either in diabetic group or SAA treatment compared with that of normal control group. We also observed the significant decrease in relaxation to ACh rather than SNP in diabetic group compared with controls, and SAA treatment could revert the ACh response. It is concluded that oral administration of SAA can significantly improve glucose metabolism and inhibit oxidative injury as well as protect against impaired vascular responsiveness in STZ-induced diabetic rats.