Oxidative Stress Mechanisms of Treadmill with Different Intensity on Endothelial Function and Ultrastructure in Spontaneously Hypertensive Rats

Objective:To investigate the effects of treadmill exercise with different intensity on spontaneously hypertensive rats' endothelial function and ultrastructure.Methods:Threemonth-old male SHR and WKY were randomly assigned to six groups:sedentary control group(SHR-C,WKY-C),moderate-intensity exercise group(SHR-M,WKY-M),and high-intensity exercise group(SHR-H,SHR-H).The animals in the exercise-trained groups ran on a motor treadmill(0°slope)at 18~20m/min(~55~65% of the maximal aerobic velocity)and26~28m/min(~75~85% of the maximal aerobic velocity),respectively.Each exercisetrained group ran 60 min per day,5days per week for 8weeks.Blood pressure examined by non-invasive methods,endothelial ultrastructure observed by transmission electron microscope,tension test to isolated vessel ring measured by DMT,protein determined by western blotting and detection for enzyme activity.Result:1)Systolic pressureand diastolic pressure in SHR-M were much lower than in SHR-C,and SHR-H significantly different from SHR-C(P<0.05).2)Oxidative product MDA demonstrated that compared to MDA in WKY-C,SHR-C had the trend to rise,but no significant difference.SHR-H were significantly higher than SHR-M(P<0.05).Antioxidant enzymes including GSH-Px,SOD demonstrated that GSH-Px in SHR-C were lower in comparison with WKY-C,GSH-Px in SHR-H and SHR-M were significantly higher compared to SHR-C(P<0.05);SOD in WKY-M were significantly higher than in WKY-C(P<0.05),SOD in SHR exercise-trained groups had no significant difference compared to SHR-C(P<0.05).3)Transmission electron microscope in SHR-C and SHR-H showed that endothelial cells' malformation,collagen proliferation.However,SHR-M showed the intact of endothelial cells.4)Endothelial-dependent vasodilator function in SHR-C wasstrikingly lower in comparison with WKY-C,SHR-M ameliorated endothelium-dependent dilation dysfunction induced by hypertension;However,endothelial-dependent dilation was apparently decreased in SHR-H compared to SHR-C(P<0.05).Conclusion:Moderate-intensity exercise can reduce the SHR blood pressure,ameliorate endothelial function and ultrastructure.Whereas high-intensity exercise has an opposite effect that the increase of oxidative stress and the disorder of endothelium dependent dilation.