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

Abstract

BackgroundHyperglycemia 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.MethodsThirty-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.ResultsThe 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.ConclusionsGiven 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.

Effects of exercise training and TrkB blockade on cardiac function and BDNF-TrkB signaling postmyocardial infarction in rats

“…The increase in the cardiac index by exercise training was due to an increase in EDV and SV but not in heart rate, consistent with a previous study in healthy rats (24). Exercise training post-MI may increase venous return to the heart by reduction in vascular resistances, similarly as observed in healthy and diabetic rats (17,24) and patients with HF (20), as well as an increase in ventricular compliance by minimizing additional scar thinning (42,54) and collagen accumulation (54). In the present study, the increase in resting LVEDP post-MI was attenuated by exercise training, which may reflect the larger LV volume and improved ventricular compliance (43) analysis was done by one-way ANOVA followed by a Bonferroni post hoc test.…”

Optical Coherence Tomography Measurements in Type 1 Diabetic Subjects with Low and Moderate Daily Physical Activity

“…The blood flow was measured using microspheres. They demonstrated the improvement of blood flow, vascular resistance, and reduction of the long-term organ dysfunctions induced by hyperglycemia inexercise-trained rats [ 37 ]. Yet another study revealed the beneficial effects of physical exercise on diabetic rats that were active before the onset of DM, with an impact on reducing oxidative stress and improving renal function [ 38 ].…”

Peer Review #1 of "Driver versus navigator causation in biology: the case of insulin and fasting glucose (v0.1)"

“…STZ acts by specifically destroying the insulin producing β cells of the pancreatic islets (Szkudelski, 2001). A low dose of STZ that destroys a substantial population of β cells but does not lead to total destruction of their population is often perceived as a good model for T2D, whereas a high dose of STZ that destroys the β cell population almost entirely is perceived as a model of T1D (Akbarzadeh et al, 2007;Asrafuzzaman et al, 2017;Freitas et al, 2015;Gajdosík et al, 1999;Kagami et al, 2008;Kovacs et al, 2011;Szkudelski, 2001;Zhang et al, 2008). We searched literature to look for studies that carefully differentiated between steady state glucose from post load glucose in STZ models but did not find any studies that make this distinction clear.…”