The Vascular Biology of Dipyridamole in Peripheral Arterial Disease (PAD)

Inclusion Criteria: * Age between 18 - 79 * Women of child bearing potential using a medically acceptable method of birth control (oral/transdermal/vaginal hormonal contraception, depo-provera injection, IUD, condom with spermicide, progestin implant, tubal ligation, oophorectomy, TAH) or abstinence. * Capacity for giving written consent * Diagnosis of PAD by: * previous angiogram (\>0.5 stenosis of a peripheral artery) * ankle-brachial index (ABI) of systolic pressure \<0.80 * previous peripheral revascularization * Smokers who smoke \< 10 cigarettes / day Exclusion Criteria: * Female subjects who are pregnant or nursing a child. * Prior bleeding event related to drug therapy * History of gastrointestinal ulceration * History of known dipyridamole and/or aspirin allergy or intolerance * History of coagulation, bleeding or blood disorders. * Recent history of myocardial infarction or stroke in the previous 6 months * Resting blood pressure of \<110mmHg systolic or \<60mmHg diastolic or of \>165mmHg systolic or \>95mmHg diastolic * Patients with active infection as documented by abnormal laboratory tests at screen * Concomitant serious illness, such as cancer, as per the principal investigator's discretion * Current use of steroids for a chronic disease process * Presence of ischemic leg ulcers * History of contact allergies to the metal leads of the NIRS * History of drug or alcohol abuse within the last 6 months. * Subject who has received an experimental drug and/or used an experimental device within 30 days of screening. * Subject who has donated ≥ one pint of blood within 8 weeks prior to screen. * Use of aspirin for 2 weeks prior to the study * Use of any other NSAID or COX-inhibitor for one week prior to the start of the study * Use of any antioxidant vitamin for 2 weeks prior to the start of the study * Use of plavix, pletal or trental for one week prior to the start of the study * Use of acetaminophen for one week prior to each study visit * Use of alcohol, caffeine or high fat foods for 24 hours prior to each study visit * Has smoked any cigarettes for 24 hours prior to each study visit * Platelet aggregation blood test less than 60 percent at Visit 1