Intense exercise training is not effective to restore the endothelial NO-dependent relaxation in STZ-diabetic rat aorta

Background: The aim of this study was to examine the effects of intense physical training on vascular function in streptozotocin-diabetic rats. We focused on the endothelium-dependent relaxation (EDR) induced by acetylcholine (ACh) and stable ADP adenosine-5'-O-(2-thiodiphosphate) (ADP beta S). Methods: Control or diabetic male Wistar rats (n=44) were randomly assigned to sedentary or trained groups. The training program consisted in a regular period of running on a treadmill during 8 weeks (10 degrees incline and up to 25 m/min, 60 min/day). The reactivity of isolated thoracic aorta rings of healthy, diabetic and/or trained has been tested. Results: ACh and ADP beta S-induced EDR were observed in phenylephrine (PE) pre-contracted vessels. As compared to sedentary control group, diabetic rats showed an increase in PE-induced contraction and a decrease in ACh and ADP beta S-induced EDR (p<0.05). Moreover, there were no increase in ACh and ADP beta S-induced EDR in diabetic rats. N-Nitro-L-Arginine Methyl Ester inhibited the nitric oxide synthase in diabetic and control rats, thereby resulting in a strong inhibition of the EDR induced by ACh and ADP beta S (10(-6) M). Conclusion: Diabetes induced an endothelium dysfunction. Nevertheless, our intense physical training was not effective to restore the aorta endothelial function.