Close relation between endothelium-dependent flow-mediated dilation in coronary and brachial artery in human

12-Week Exercise Training, Independent of the Type of Exercise, Attenuates Endothelial Ischaemia-Reperfusion Injury in Heart Failure Patients

Introduction: Reperfusion is required to salvage ischaemic tissue, but also causes further damage (i.e., ischaemia/reperfusion-injury). Heart failure patients reveal exaggerated ischaemia/reperfusion-injury, whilst traditional ischaemic preconditioning cannot prevent ischaemia/reperfusion-injury. Exercise training may be a more powerful preconditioning stimulus, especially high-intensity interval training given the similarities with ischaemic preconditioning. Therefore, we examined the impact of 12-week continuous training vs. high-intensity interval training on brachial artery endothelial ischaemia/reperfusion-injury in heart failure patients New York Heart Association-class II-III.

Methods: Twenty heart failure patients (male:female 19:1, 64 ± 8 years, ejection fraction 38 ± 6%) were allocated to 12-weeks of high-intensity interval training (10^∗1-min 90% maximal workload – 2.5-min 30% maximal workload) or continuous training (30-min 60–75% maximal workload). Before and after the intervention, we measured brachial artery endothelial function with flow-mediated dilation (FMD) before and after ischaemia/reperfusion (5-min ischemic exercise, 15-min reperfusion).

Results: Ischaemia/reperfusion caused a significant decline in FMD (continuous training (n = 10): 5.2 ± 2.5 to 3.4 ± 1.6%, high-intensity interval training (n = 10): 5.3 ± 2.6 to 3.5 ± 1.6%, P = 0.01), which was not different between groups (P > 0.05). Training improved maximal workload and fitness (P < 0.05), with no differences between groups (P > 0.05). Exercise training did not alter FMD (P > 0.05), whilst ischaemia/reperfusion did not impair FMD after exercise training (continuous training: 4.8 ± 3.0 to 4.2 ± 2.3%, high-intensity interval training: 4.7 ± 2.5 to 3.8 ± 2.3%, P > 0.05). No changes were found in FMD before or after ischaemia/reperfusion after 12-weeks in controls (n = 9).

Conclusion: We found that 12-week exercise training in heart failure patients mitigated endothelial ischaemia-reperfusion injury, an effect independent of the type of exercise. These changes may contribute to the cardioprotective effects of exercise training, whilst our findings highlight the potency of exercise as a preconditioning stimulus.

Review: Endothelial dysfunction and pre-symptomatic atherosclerosis in type 1 diabetes — pathogenesis and identification

The vascular endothelium offers an attractive model for detecting functional abnormalities prior to structural changes in the vasculature. Demonstration of progression from endothelial dysfunction through to atherosclerosis is required. Measurements of forearm bloodflow, biochemical markers and biophysical assessments of the endothelium have been employed as research tools for investigating pre-symptomatic atherosclerosis.

However, studies examining endothelial function in type 1 diabetes have been sparse and conflicting. Differences in methodology and the study populations were potential confounding factors. Augmented vasodilatory prostanoids compensate for reduced nitric oxide bioavailability in determining endothelial function in type 1 diabetes. Hyperglycaemia appears to be the initiating event in type 1 diabetes which promotes a variety of biochemical events which are pathogenic to the endothelium.

Improved understanding of the endothelium may facilitate the development of novel diagnostic tools and interventions targeting the accelerated atherosclerosis associated with type 1 diabetes.