To investigate if treatment with ticagrelor can mitigate the transient loss of endothelium-dependent vasodilatation of the resistance vasculature following a short period of ischemia, compared with clopidogrel at standard clinical doses. The effect of ticagrelor or clopidogrel will be studied after a loading dose and after a two weeks period of regular intake on FBF in response to the vasodilators acetylcholine or nitroglycerin before and 10 min after a 20 min forearm ischemia, respectively.

Ischemia-reperfusion (IR) causes tissue injury. Preclinical animal data suggest that ticagrelor but not clopidogrel protects against IR injury due to inhibition of cellular adenosine uptake and NO-synthase stimulation. It is unclear if this action is part of the beneficial clinical effect of ticagrelor in patients with a history of acute coronary syndrome. The preventive action of ticagrelor on IR injury may also be of interest for the peripheral vasculature, where IR injury is known to result in endothelial dysfunction. This study aims to investigate if treatment with ticagrelor can mitigate the transient loss of endothelium-dependent vasodilatation of the resistance vasculature following a short period of ischemia, compared with clopidogrel at standard clinical doses. We will study the effect of ticagrelor or clopidogrel after a loading dose and after a two weeks period of regular intake on forearm blood flow (FBF) reactivity in response to the vasodilators acetylcholine (ACh; endothelium-dependent agonist) or nitroglycerin (GTN; endothelium-independent vasodilator) before and 10 min after a 20 min forearm ischemia, respectively

Inclusion Criteria:

• Healthy male subjects; 18 - 40 years of age
• Body mass index between 18 and 27 kg/m2
• Written informed consent
• Normal findings in medical & bleeding history
• Non-smoking

Exclusion Criteria:

• Regular intake of any medication including OTC drugs and herbals within 2 weeks before IMP administration
• Known coagulation disorders (e.g. haemophilia, von Willebrand´s disease)
• Known disorders with increased bleeding risk (e.g. peridontosis, haemorrhoids, acute gastritis, peptic ulcer, intestinal ulcer)
• Known sensitivity to common causes of bleeding (e.g. nasal)
• History of thromboembolism
• History of occlusive vascular diseases
• History of vascular anomalies
• Impaired liver function (AST, ALT, gGT, bilirubin >2 x ULN)
• Impaired renal function (serum creatinine > 1.3 mg/dl)
• Any other relevant deviation from the normal range in clinical chemistry, haematology or urine analysis
• HIV-1/2-Ab, HbsAg or HCV-Ab positive serology
• Systolic blood pressure above 145 mmHg, diastolic blood pressure above 95 mmHg
• Known allergy against any test agent under study
• Regular daily consumption of more than on litre of xanthine-containing beverages or more than 40g alcohol
• Participation in another clinical trial during the preceding 3 weeks