부산대학교 도서관

Exercise limitation is a cardinal feature in individuals with chronic respiratory disease (CRDs). This limitation occurs directly due to impairment and disability of one or more of the physiological systems (pulmonary system, cardiovascular system, and skeletal muscle), which contribute to breathlessness and reduced physical activity. Dietary nitrate supplementation can enhance NO availability via a nitrate-nitrite-NO pathway, and has been proposed as a potential complementary approach to improve exercise capacity in people with CRDs. However, studies to date have generally been short-term and existing studies on dietary nitrate supplementation in people with lung disease have mostly focused on COPD, typically in less severe disease. The objectives of this thesis were as follows: 1) to further extend the knowledge and synthesise the current evidence and evaluate the impact of dietary NO3- supplementation on exercise capacity and cardiovascular parameters in CRDs (Chapter 3), 2) to investigate the effects of acute NO3- administration on exercise performance, blood pressure, and endothelial function in hypoxic patients with pulmonary hypertension (Chapter 4), and 3) to investigate if there is a link between blood nitrate levels and the severity of lung disease (Chapter 5). Results from Chapter 3 indicated that dietary nitrate supplementation has the potential to reduce cardiovascular risk by lowering blood pressure in people with COPD as well as improving exercise capacity. In Chapter 4, following acute consumption of nitrate-rich beetroot juice (NR-BRJ), study participants walked for longer than following dosing with placebo. In Chapter 5, plasma nitrate levels negatively correlated with blood pressure parameters and positively correlated with the endothelial function and serum potassium level in stable COPD patients. However, no correlations were found between the plasma nitrate and breathlessness or any other marker of disease severity. The findings suggest that dietary nitrate supplementation might be used as a non-pharmacological intervention to augment exercise in people with CRDs and protect against vascular events. Larger and longer trials are required to determine the optimal dose and to understand the possible mechanisms of dietary nitrate supplementation in pulmonary circulation.