Effect of aerobic exercise training on regional blood flow and vascular resistance in diabetic rats

Background: Hyperglycemia has been associated with decreased blood flow in various organs, leading to tissue damage and dysfunctions. Exercise training (ET) is known to promote beneficial changes in the autonomic nervous system and may have effects on circulation. The aim of this study was to evaluate coronary and renal blood flows and vascular resistances after ET in diabetic rats. Methods: Thirty-two rats were divided into four groups (n = 8): sedentary control (SC), trained control (TC), sedentary diabetic (SD), trained diabetic (TD). Diabetes was induced by an injection of streptozotocin (STZ, 50 mg/kg). The ET was performed on a treadmill for 10 weeks. The blood flows were measured using colored microspheres. Results: The diabetic groups presented hyperglycemia (blood glucose >350 mg/dL) and ET did not change this parameter. The SD group showed reduced renal blood flow when compared to SC group, and ET was able to normalize this parameter in TD rats (SC: 4.3 +/- 0.5; TC: 2.9 +/- 0.3; SD: 1.9 +/- 0.4; TD: 3.2 +/- 0.4 mL/min/g). TD group presented increased coronary blood flow in relation to SD group (SC: 2.3 +/- 0.23; TC: 2.8 +/- 0.5; SD: 1.2 +/- 0.4; TD: 3.0 +/- 0.4 mL/min/g). The heart and kidneys vascular resistance were increased in SD group when compared to SC group, and ET was able to reverse these changes. Conclusions: Given the relevance of cardiomyopathy and nephropathy in mortality of diabetics, our results demonstrated that ET is effective in improving coronary and renal blood flows and vascular resistances in STZ-diabetic rats, reinforcing the positive role of this approach in preventing hyperglycemia-induced long-term organ damage.