Essential hypertension is characterized by impaired endothelial function. Data derived from normotensive subjects with a genetic predisposition to arterial hypertension suggest that endothelial dysfunction is a cause rather than a consequence of the condition. Given that, in normotensive offspring of hypertensive parents, impaired endothelium dependent vasodilation can be restored by supplementation of the nitric oxide (NO) precursor L-arginine, a defect in the L-arginine/NO pathway can be postulated. The investigators at the University of Erlangen-Nuremberg, hypothesize that impaired endothelial function in essential hypertension is associated with alterations in L-arginine metabolism and transport. This study will determine whether metabolism and transport of L-arginine are altered in patients with essential hypertension and whether these potential alterations can be targeted therapeutically.

Inclusion Criteria:

• Males, ages 18-65
• Male and female healthy control subjects ages 18-65

Exclusion Criteria:

• Any other coexisting condition
• Advanced damage of vital organs (grade III und IV retinopathy)
• Therapy with a not approved concomitant medication in the last 4 weeks prior to intake of the first trial medication, especially lipid lowering and antidiabetic medications (washout phase)
• Blood donation within the last 4 weeks
• Patients with arterial fibrillation or atrioventricular (AV)-block (II and more)
• Patients with anamnestic myocardial infarct
• Patients with depression
• Patients with seizure disorders
• Patients with unstable angina pectoris including electrocardiogram (ECG)-aberrations or cardiac insufficiency New York Heart Association (NYHA) Stadium III and IV
• History of a malignant illness with the exception of those patients who have recovered for more than 10 years or have a basalioma of the skin.
• Actual or anamnestic alcohol or drug abuse
• History of organ transplant
• Anaphylaxis or known therapy resistance to any of the used test matters.
• Therapy with a not approved concomitant therapy
• Participation in another study within three months prior to study inclusion
• Illnesses, which can influence the pharmacodynamics or pharmacokinetics of the test substance
• Liver or kidney diseases: SGOT, GPT , γ-GT, AP, bilirubin and creatinine above 200% of standard
• Patients who are not sufficiently compliant; or patients who are not capable or willing to appear for controlling visits.
• Severe or unstable medical or psychiatric illnesses, which will, in the estimation of the examiner, endanger the safety of the proband or the successful participation in the study
• Presumed risk of transmission of HIV or hepatitis via blood from the proband