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Angiotensin-Converting Enzyme Gene Polymorphisms and Tissue Oxygenation During Exercise: Discussion

Angiotensin-Converting Enzyme Gene Polymorphisms and Tissue Oxygenation During Exercise: DiscussionThe mean PAP after exercise was negatively correlated with ADo2/AVo2 (r = — 0.423, p = 0.0076; Fig 3). However, the mean PAP after exercise was not significantly correlated with Pvo2 after exercise (r = — 0.303, p = 0.515) and with ALactate (r = 0.253, p = 0.123). In this study, we evaluated the ADo2/AV02 during exercise as an index of convective oxygen transport to the peripheral tissues. We found that the ADo2/ AV02 was significantly lower in patients with the DD genotype than in those with the II and ID genotypes, and that the mean PAP after exercise was negatively correlated with the ADo2/AV02. Pulmonary hypertension with exercise can interfere with convective oxygen transport because of an inappropriate increase in Qt in response to exercise due to unloading of the left ventricle due to relative right ventricular failure caused by the exercise-induced increase in pulmonary afterload. In this study, the magnitude of pulmonary hypertension with exercise was greatest in patients with the DD genotype, with ID genotype patients having less pulmonary hypertension than DD genotype patients, and II genotype patients having the least pulmonary hypertension. Thus, the lower ADo2/AVo2 during exercise in patients with the DD genotype could be supported. Oxygen diffuses from the alveolar air into the pulmonary circulation and is transported to the muscles. In patients with COPD, the proportion of the total Vo2 utilized by the respiratory muscles during exercise is higher than in normal subjects, and the Vo2 available to the exercising nonrespiratory muscles would be correspondingly decreased. Therefore, it is conceivable that the disturbance of oxygen transport during exercise has a significant effect on the failure of nonrespiratory tissue oxygenation, in which oxygen transport to the peripheral exercising muscles is already reduced by blood flow diversion to respiratory muscles. canadian health & care mall

Fig3
Figure 3. Correlation between ADo2/AV o2, Pvo2 after exercise, A Lactate, and mean PAP after exercise.