Subjects with a known diagnosis of peripheral artery disease as measured by an abnormal ankle
brachial index (<.9 or >1.1) will undergo a single 5 min exposure of 670 nm light, 1 cm above
the gastrocnemius muscle. Blood flow will be measured by infusion of ultrasound contrast and
subsequent acquisition of ultrasound images. 2 blood samples will be collected for
measurement of nitric oxide metabolites.