Does detraining restore influence of exercise training on microvascular responses in streptozotocin-induced diabetic rats?

Several findings demonstrated that exercise training has therapeutic and protective effects in type 1 diabetes and could correct micro and macro vascular dysfunction. Regarding all benefits of exercise training on vascular function, however, the mechanisms and persistence of these benefits are only partially understood.Method: Male Wistar rats (220 ± 10 g, N = 85) were made diabetic by streptozotocin (60 mg/kg, subcutaneously). One week after diabetes induction, animals were submitted to exercise training for 10 weeks on a treadmill and detrained for 5 weeks. To characterize cutaneous microvascular responses by Laser Doppler flowmetery, animals were deeply anaesthetized by intra peritoneal injection of pentobarbital sodium and placed on a heating pad, a rectal thermometer was inserted, and body temperature was maintained at 37 ± 0.5 °C. A tracheotomy was performed to minimize respiratory difficulties.Results in diabetic rats after training: (1) l-arginine (l-ARG) and Acetylcholine (Ach)-induced cutaneous perfusion were increased. However, these effects were reversed by detraining and Nw-nitro-l-arginine (l-NNA); (2) sodium nitroprusside (SNP)-induced cutaneous perfusion did not significantly change; and (3) cutaneous microvascular responses to SNP were reduced after detraining.The results suggest that in diabetic rats, beneficial effect of regular exercise on cutaneous microvascular endothelium-dependent dilatation and l-ARG/Nitric oxide pathway activity was approximately reversed by 5 weeks of detraining. Training did not affect endothelium-independent dilatation; however, detraining reduced it significantly.

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