Erigeron breviscapus prevents defective endothelium-dependent relaxation in diabetic rat aorta

We examined the endothelium-dependent relaxation response to acetylcholine (Ach) in streptozotocin-induced diabetic rat aorta at the stages of 2- and 6-wks' duration in vitro, and compared with another two groups which were t reated with dietary supplement of 0.1% Aminoquanidine (AG) and 0.5% Erigero n breviscapus(EB) from 1-week of diabetes induction. At the stage of 2-wks' duration of diabetes, relaxation responses to lower concentrations of Ach in 0.3uM phenylepherine-precontracted aortas were diminished significantly (P<0.05) compared with age-matched control, but the maximal relaxation of A ch remained unchanged. At the stage of 6-wks' duration, diabetes caused an approximately 60% (P<0.001) deficit in maximum relaxation, and this was sig nificantly (P<0.001) prevented in AG and EB treated groups. There was an ap proximately 40% enhancement in the maximum contractile response to phenylep herine with diabetes (P<0.05), which was unaffected significantly by AG and EB treatments. The data suggest that the defective endothelium-dependent r elaxation in diabetic rat aorta occurred as early as 2-wks' duration of dia betes, and the treatments of AG and EB could protect vascular endothelium a lthough the deficits in vascular smooth muscle contractile responses were n ot protected.