Experimental Research On Endothelial Function In Diabetes By Ultrasonography

Objective:To evaluate application of high-frequency ultrasound in Diabetic vascular endothelial function and observe the changes of vascular endothelial function after early drug intervention by the adoption of high-frequency ultrasound to assess the vascular endothelium-dependent and independent diastolic function in Diabetic rabbit model.Methods:1.36 Japanese Giant Ear Rabbits were randomly divided into two groups control group(group A,n=18) and Diabetic group (group B,n=18),which were developed by alloxan.Then group A and B were divided into three sub-groups respectively(n=6 in each subgroup): 6 weeks group (A1, B1), 12 weeks group (A2, B2), 18 weeks (A3, B3).At different periods of Diabetic Course(the 6th week, 12th week, 18th week), blood glucose and serum level of lipids were tested, and the reactive hyperemia of rabbits and their changes in diameter of external iliac artery after taking nitroglycerin were inspected with high-frequency ultrasound, meanwhile the right external iliac artery was stained by HE and observed by light microscope. 2.24 Japanese Giant Ear Rabbits were randomly divided into three groups:A.Diabetic control group, B.VitC + VitE treatment group, C.Ato treatment group.The rabbits models of Diabetes mellitus were developed by alloxan.Group B and C were given VitC + VitE and Ato intervention respectively for eighteen weeks.At different periods of Diabetic Course(the 6th week, 12th week, 18th week), blood glucose and serum level of lipids were tested, and the reactive hyperemia of rabbits and their changes in diameter of external iliac artery after taking nitroglycerin were inspected with high-frequency ultrasound, meanwhile the right external iliac artery was stained by HE and observed by light microscope.Results:1.At the 6th week of Diabetic duration, the serum level of TG,TC,LDL-C, HDL-C in Diabetes rabbits began to change.With comparison to that of control group at the same period ,the serum level of TG,TC,LDL-C in Diabetes rabbits increased significantly(P <0.05) while HDL - C did not decrease significantly until the 12th week of Diabetic duration.2.With the extension of the course, the function of vascular endothelial -dependent relaxation and endothelial-independent relaxation in Diabetes group reduced to a greater or lesser degree.At the 6th week the function of vascular endothelial-dependent relaxation were damaged more significantly than that of the control group at the same period(P <0.05).There was no significant difference in the functional damage of vascular endothelial-independent relaxation between two groups at the 6th week (P> 0.05) until the 12th week.3.At the 6th week, there was no evidences of arteriosclerosis in the external iliac artery of Diabetic rabbits under observation of light microscope, while at the 12th week, the endothelial cells exfoliated and some multi-shedding foam cells outstood into the lumen, and the pathological changes were more serious at the 18th week.4.Compared with that of the same period of Group A, EDD% of external iliac artery in Group B had improved, but there was no significant difference untill the 12th week (P <0.05), while EDD% of external iliac artery of Group C improved significantly from the 6th week compared with that of Group A and B (P <0.05).Compared with that of Group A at the same period ,EID% of Group B and C after drug treatment improved significantly at the 18th and 12th week respectively while no significant improvement at the 6th week(P> 0.05).Conclusions:1.High-frequency ultrasound can detect the early changes of diabetic vascular endothelial function, and the ultrasonic changes are corresponding to the pathological changes of vascular endothelial cells.2. The damage of Diabetic endothelium-dependent-dilatation occurs earlier than that of endothelium-independent-dilatation, that is to say the functional damage of vascular endothelium occurs earlier than morphological abnormalities.3.Ato can improve diabetic vascular endothelial function, and the mechanism includes lipid-regulating function and non- lipid-regulating function.4.Combination of VitC and VitE can improve diabetic vascular endothelial function.