Leukocyte-endothelial cell interaction is attenuated by low-intensity exercise training and vitamin C supplementation in diabetic rats.

Objective: To determine the effects of vitamin C supplementation and low-intensity exercise training on diabetesinduced endothelial dysfunction. Methods: Male Spraque-Dawley rats were randomly divided into five groups: control (Con), diabetes (DM) (streptozotocin; 50 mg/kg BW, i.v.), diabetes with supplemented vitamin C (DM+Vit.C; 1 g/L mixed in drinking water), diabetes with low-intensity exercise-trained (DM+Ex; running 5 times/week with 13-15 m/min velocity for 30 minutes) and diabetes with supplemented vitamin C and exercisetrained (DM+Vit.C+Ex) groups. The number of leukocyte-endothelial cell (EC) interactions in mesenteric postcapillary venules was monitored using intravital fluorescence videomicroscopy. Liver malondialdehyde (MDA) level, an indicator for oxidative stress, was determined by using the thiobarbituric acid reaction. Results: At 24 weeks, the plasma vitamin C level was significantly increased (p<0.05) in DM+Vit.C and DM+Vit.C+Ex rats when compared with DM rats. DM+Ex and DM+Vit.C+Ex rats had lower triglyceride levels and heart weights when compared with DM rats (P<0.05). Mean arterial pressures were significantly decreased in all treatment groups. DM rats had significantly higher malondialdehyde (MDA) levels and lower activities of superoxide dismutase (SOD) than Con. The number of adherent leukocytes and levels of MDA were significantly lower in DM+Vit.C, DM+Ex and DM+Vit.C+Ex than those of DM rats. Conclusion: The increased leukocyte-EC adherence in diabetic rats is significantly related to increased ROS, based on lower MDA levels. Vitamin C supplementation and regular low-intensity exercise training can prevent these deleterious effects, including hypertension, cardiac hypertrophy, hypertriglyceridemia, and leukocyte-EC adherence. Vitamin C supplementation combined with low-intensity exercise training is highly effective in preventing diabetic cardiovascular complications.