Effects of dietary nitrate supplementation on the oxygen cost of exercise and walking performance in individuals with type 2 diabetes: a randomized, double-blind, placebo-controlled crossover trial.

Dietary nitrate supplementation has been shown to reduce the oxygen (O2) cost of exercise and enhance exercise tolerance in healthy individuals. This study assessed whether similar effects could be observed in individuals with type 2 diabetes (T2DM). In a randomized, double-blind, placebo-controlled crossover study, 48 participants with T2DM supplemented their diet for 4 days with either nitrate-rich beetroot juice (70ml/day, 6.43mmol nitrate/day) or nitrate-depleted beetroot juice as placebo (70ml/day, 0.07mmol nitrate/day). After each intervention period, resting plasma nitrate and nitrite concentrations were measured subsequent to participants completing moderate-paced walking. Pulmonary gas exchange was measured to assess the O2 cost of walking. After a rest period, participants performed the 6-min walk test (6MWT). Relative to placebo, beetroot juice resulted in a significant increase in plasma nitrate (placebo, 57±66 vs beetroot, 319±110µM; P < 0.001) and plasma nitrite concentration (placebo, 680±256 vs beetroot, 1065±607nM; P < 0.001). There were no differences between placebo juice and beetroot juice for the O2 cost of walking (946±221 vs 939±223ml/min, respectively; P = 0.59) and distance covered in the 6MWT (550±83 vs 554±90m, respectively; P = 0.17). Nitrate supplementation did not affect the O2 cost of moderate-paced walking or improve performance in the 6MWT. These findings indicate that dietary nitrate supplementation does not modulate the response to exercise in individuals with T2DM.

The effect of dietary nitrate supplementation on the oxygen cost of cycling, walking performance and resting blood pressure in individuals with chronic obstructive pulmonary disease: A double blind placebo controlled, randomised control trial.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) results in exercise intolerance. Dietary nitrate supplementation has been shown to lower blood pressure (BP), reduce the oxygen cost of exercise, and enhance exercise tolerance in healthy volunteers. This study assessed the effects of dietary nitrate on the oxygen cost of cycling, walking performance and BP in individuals with mild-moderate COPD. METHODS: Thirteen patients with mild-moderate COPD were recruited. Participants consumed 70 ml of either nitrate-rich (6.77 mmol nitrate; beetroot juice) or nitrate-depleted beetroot juice (0.002 mmol nitrate; placebo) twice a day for 2.5 days, with the final supplement ~3 hours before testing. BP was measured before completing two bouts of moderate-intensity cycling, where pulmonary gas exchange was measured throughout. The six-minute walk test (6 MWT) was completed 30 minutes subsequent to the second cycling bout. RESULTS: Plasma nitrate concentration was significantly elevated following beetroot juice vs. placebo (placebo; 48 ± 86 vs. beetroot juice; 215 ± 84 µM, P = 0.002). No significant differences were observed between placebo vs. beetroot juice for oxygen cost of exercise (933 ± 323 vs. 939 ± 302 ml: min(-1); P = 0.88), distance covered in the 6 MWT (456 ± 86 vs. 449 ± 79 m; P = 0.37), systolic BP (123 ± 14 vs. 123 ± 14 mmHg; P = 0.91), or diastolic BP (77 ± 9 vs. 79 ± 9 mmHg; P = 0.27). CONCLUSION: Despite a large rise in plasma nitrate concentration, two days of nitrate supplementation did not reduce the oxygen cost of moderate intensity cycling, increase distance covered in the 6 MWT, or lower BP.

Safety and feasibility of dobutamine stress cardiac magnetic resonance for cardiovascular assessment prior to renal transplantation.

AIMS: Current guidelines recommend cardiovascular risk assessment prior to renal transplantation. There is currently no evidence for the role of cardiovascular magnetic resonance (CMR) in this population, despite an established evidence base in the non-chronic kidney disease (CKD) population. Our aim is to determine the feasibility and safety of dobutamine stress CMR (DSCMR) imaging in the risk stratification of CKD patients awaiting renal transplantation. METHODS: CKD patients who were deemed at high risk for coronary artery disease (CAD) and awaiting renal transplantation underwent DSCMR. RESULTS: Forty-one patients whose median age was 56 years (range 28­73 years) underwent DSCMR. Nineteen were undergoing haemodialysis, 10 peritoneal dialysis and 12 pre-dialysis. The aetiology of the renal failure was diabetes mellitus in 29%, glomerulonephritis in 24%, hypertension in 22% and autosomal dominant polycystic kidney disease in 10%. Thirty-eight patients (93%) achieved the end point, either positive for ischaemia or negative, achieving at least 85% of age-predicted heart rate. Two of them did not achieve target heart rate and one was discontinued because of severe headache. Of the 38 patients who achieved the end point, 35 (92%) were negative for inducible wall motion abnormalities and four (10%) were positive. There were no serious adverse effects. CONCLUSION: DSCMR is a well tolerated and viable investigation for the cardiovascular risk stratification of high-risk CKD patients prior to renal transplantation. DSCMR already has an established evidence base in the non-CKD population with superiority over other noninvasive techniques. Larger studies with outcome data are now required to define its true utility in the CKD population.

The difference in blood pressure readings between arms and survival: primary care cohort study.

OBJECTIVE: To determine whether a difference in systolic blood pressure readings between arms can predict a reduced event free survival after 10 years. DESIGN: Cohort study. SETTING: Rural general practice in Devon, United Kingdom. PARTICIPANTS: 230 people receiving treatment for hypertension in primary care. INTERVENTION: Bilateral blood pressure measurements recorded at three successive surgery attendances. MAIN OUTCOME MEASURES: Cardiovascular events and deaths from all causes during a median follow-up of 9.8 years. RESULTS: At recruitment 24% (55/230) of participants had a mean interarm difference in systolic blood pressure of 10 mm Hg or more and 9% (21/230) of 15 mm Hg or more; these differences were associated with an increased risk of all cause mortality (adjusted hazard ratio 3.6, 95% confidence interval 2.0 to 6.5 and 3.1, 1.6 to 6.0, respectively). The risk of death was also increased in 183 participants without pre-existing cardiovascular disease with an interarm difference in systolic blood pressure of 10 mm Hg or more or 15 mm Hg or more (2.6, 1.4 to 4.8 and 2.7, 1.3 to 5.4). An interarm difference in diastolic blood pressure of 10 mm Hg or more was weakly associated with an increased risk of cardiovascular events or death. CONCLUSIONS: Differences in systolic blood pressure between arms can predict an increased risk of cardiovascular events and all cause mortality over 10 years in people with hypertension. This difference could be a valuable indicator of increased cardiovascular risk. Bilateral blood pressure measurements should become a routine part of cardiovascular assessment in primary care.