ABSTRACT
AIM: To investigate the changes of potassium channels in thoracic aorta of streptozotocin-induced diabetic mouse in the early stage of diabetes mellitus. METHODS: The effects of 60 mmol/L KCl, phenylephrine (PE), sodium nitroprusside (SNP) were measured and concentration-response curves to SNP were determined in the presence and in the absence of the inhibitors of potassium channels on the thoracic aortic rings of diabetic and age-matched control mice in vitro. RESULTS: STZ-diabetic mice showed a significant increase in the maximum contractile response and sensitivity of thoracic aorta to 60 mmol/L KCl and PE. The endothelium-independent relaxation response to SNP was increased by diabetes and were decreased significantly by pretreatment of the vessels with 1 mmol/L tetraethylammonium (TEA), 1 mmol/L 4-aminopyridine (4-AP) and 10 ?mol/L glibenclamide in diabetes thoracic aorta. Only 4-AP decreased relaxation response to SNP in age-matched control mice. The -logIC 50 difference of TEA in thoracic aorta rings of diabetes was significantly higher than age-matched control mice.CONCLUSION: In early stage of diabetes mellitus, the opening or expression of K Ca channels is significantly enhanced.The opening of K ATP channels is also enhanced in this stage.