Effects of vasoconstrictor and endothelium-dependent relaxationagent on thoracic aortic rings of diabetes mice

AIM: To discuss the effects of vasoconstrictor and endothelium-dependent relaxation agent on the thoracic aortic rings in different stages of diabetes mellitus. METHODS: Streptozotocin (STZ, 40 mg/kg) was injected intraperitoneally to establish diabetic model in C57BL/6J mice. At the 17th, 22nd, 28th week, diabetic and age-matched control mice were sacrificed respectively and the effects of vasoconstrictors: phenylephrine (PE), 60 mmol/L KCl and endothelium-dependent relaxation agent respectively (ACh) were measured in two groups using thoracic aortic rings. RESULTS: The level of fasting plasma glucose concentration 2 weeks after STZ treatment increased higher (≥11.1 mol/L) in STZ-induced diabetic mice than that in age-matched controls, and maintained at this level in entire experiment course. On the contrary, the weight was decreased significantly. The responses of thoracic aortic rings in STZ-induced diabetic mice to PE were increased, unaltered and increased at the 17th, 22nd, 28th weeks, respectively compared to that in age-matched controls. The responses to 60 mmol/L KCl were also increased in all stages. While the responses to ACh were increased, unaltered and decreased at the 17th, 22nd, 28th weeks, respectively compared to that in age-matched controls. CONCLUSION: The responses of thoracic aortic rings to vasoconstrictor enhance in STZ-induced diabetic mice. However, the endothelial functions potentiate initially due to compensation, and then lower exhibiting endothelial damage.