Peripheral arterial disease (PAD) is a debilitating condition that is characterised by a reduction in leg blood flow capacity and a reduced exercise tolerance. The degree to which blood flow is impaired during low intensity exercise, and the precise mechanism of this blood flow impairment, is not known. The objective of this study was to compare leg blood flow and vessel dilation during low intensity exercise and passive movement, and to assess levels of key proteins of vasodilator pathways in participants with and without PAD. Ten PAD (age: 68.5 ± 6.5 y) and 9 control (age: 62.1 ± 12.3 y) participants underwent duplex ultrasound measures of femoral artery blood flow and vessel diameter at rest, following thigh-cuff occlusion (reactive hyperaemia), and during 5-min bouts of passive, active (10 W) and maximal seated leg-kicking exercise. Resting biopsy samples were obtained from the vastus lateralis to determine muscle protein content for phosphorylated endothelial nitric oxide synthase, cyclooxygenase 1 and 2, thromboxane synthase, prostacyclin synthase, endothelin B receptor, and NADPH oxidase. Blood flow did not differ between groups at rest (PAD: 127 ± 54; CON 189 ± 76 ml.min-1) or during the final stage of passive (PAD: 221 ± 148; CON 280 ± 157 ml.min-1) and active (PAD: 1476 ± 773; CON 1856 ± 1061 ml.min-1) exercise. PAD participants tended (p = 0.3, NS) to have lower blood flow during maximal exercise (PAD: 2596 ± 1092; CON 3197 ± 1323 ml.min-1), reflecting their lower maximal workloads. Thirty seconds after cuff occlusion, changes in blood flow (PAD: 176 ± 198; CON 962 ± 333 ml.min-1) and vessel diameter (PAD: -2.9 ± 2.9; CON 0.4 ± 0.7 mm) were smaller in PAD. PAD subjects had significantly greater levels of NADPH oxidase (PAD: 1.04 ±0.59; CON 0.50±0.19 arbitrary units). An important and novel finding is that individuals suffering from PAD have elevated levels of NADPH oxidase which produces reactive oxygen species and may reduce the bioavailability of nitric oxide and therefore interfere with vessel health and reactivity. While PAD participants had normal dilation and blood flow during rest and low-intensity exercise, they demonstrated impaired responses during reactive hyperemia.
6th Exercise & Sports Science Australia (ESSA) Conference and Sports Dietitians Australia Update: Research into Practice, Adelaide, Australia 10-12 April 2014
Proceedings of the 6th Exercise & Sports Science Australia Conference and Sports Dietitians Australia Update /