ascorbic-acid and Peripheral-Arterial-Disease

Exaggerated blood pressure (BP) responses to dynamic exercise predict cardiovascular mortality in patients with peripheral arterial disease (PAD). However, the underlying mechanisms are unclear and no attempt has been made to attenuate this response using antioxidants. Three physiological studies were conducted in patients with PAD and controls. In Protocol 1, subjects underwent 4 min of low-intensity (0.5-2.0 kg), rhythmic plantar flexion in the supine posture. In Protocol 2, patients with PAD received high-dose ascorbic acid intravenously before exercise. In Protocol 3, involuntary exercise was conducted via electrical stimulation of the tibial nerve. The primary outcome measure was Δ mean arterial pressure (MAP) during the first 20 s of exercise (i.e. the onset of sympathoexcitation by muscle afferents). Compared to controls, patients with PAD had significantly greater ΔMAP during plantar flexion, particularly at 0.5 kg with the most affected leg (11 ± 2 vs. 2 ± 1 mmHg) as well as the least affected leg (7 ± 1 vs. 1 ± 1 mmHg). This augmented response occurred before the onset of claudication pain and was attenuated by ∼50% with ascorbic acid. Electrically evoked exercise also elicited larger haemodynamic changes in patients with PAD compared to controls. Further, the ΔMAP during 0.5 kg plantar flexion inversely correlated with the ankle-brachial index, indicating that patients with more severe resting limb ischaemia have a larger BP response to exercise. The BP response to low-intensity exercise was enhanced in PAD. Chronic limb ischaemia may sensitize muscle afferents and potentiate the BP response to muscle contraction in a dose-dependent manner.

Topics: Aged; Antioxidants; Ascorbic Acid; Blood Pressure; Electric Stimulation; Exercise; Female; Heart Rate; Humans; Male; Middle Aged; Oxidative Stress; Peripheral Arterial Disease; Reflex; Tibial Nerve

There are limited studies of nutrient intake and peripheral artery disease (PAD). Some studies have not accounted for the functional consequences of PAD, potentially leading to biased results. To determine the associations between intakes of dietary fiber, folate, vitamins A, C, E, and B6 and PAD.. Cross-sectional analysis of 6534 adults aged 40 years and older in the U.S. National Health and Nutrition Examination Survey between 1999 and 2004, including measurement of ankle-brachial index (ABI) and nutrient intake by 24-h dietary recall. Weighted multivariable logistic regression models to determine odds ratios and 95% confidence intervals.. The prevalence of PAD (ABI < 0.9) was 5.3% (4.7-5.9). Inverse associations between PAD and intakes of fiber, folate, and vitamins A, B6, C, and E were statistically significant when adjusting for age, sex, hypertension, diabetes and smoking. In models further adjusted for energy intake and physical activity, these odds ratios all became null (p ≥ 0.1).. In this sample, dietary fiber, folate, and vitamins B6, C, and E were not associated with PAD after accounting for energy intake and activity. Adjustment for energy and physical activity are essential to avoid bias due to reverse causation in cross-sectional studies of diet and PAD.

Topics: Adult; Aged; Ankle Brachial Index; Ascorbic Acid; Body Mass Index; Cross-Sectional Studies; Diet Records; Dietary Fiber; Energy Intake; Feeding Behavior; Female; Folic Acid; Humans; Logistic Models; Male; Mental Recall; Micronutrients; Middle Aged; Motor Activity; Multivariate Analysis; Nutrition Surveys; Peripheral Arterial Disease; Prevalence; Sedentary Behavior; Vitamin A; Vitamin B 6; Vitamin E

Topics: Ascorbic Acid; Humans; Peripheral Arterial Disease; Peripheral Vascular Diseases; Vascular Diseases; Vitamins