Effect of Losartan on Retinal Endothelial Function in Patients With Essential Hypertension

Inclusion Criteria: Male and female patients aged 18-65 years with essential hypertension Exclusion Criteria: Secondary forms of hypertension Advanced damage of vital organs (grade III and IV retinopathy) History of serious hypersensitivity reaction to AT1-receptor blockers Actual or anamnestic alcohol- or drug abuse. Smokers or ex-smokers < 1 year. Patients with Diabetes mellitus (oral medication or insulin). Patients with arterial fibrillation or AV-Block (II° or more). Patients with anamnestic myocardial infarction. Patients with instable angina pectoris including EcG-aberrations or cardiac insufficiency NYHA III or IV. History of malignancy (unless a documented disease-free period exceeding 10 years is present) with teh exception of basal cell carcinoma of the skin History of allograft transplantation Therapy with not approved concomitant medication, or participation in a clinical study within 4 weeks preceding treatment start. Disease which interfere with the pharmacodynamics and pharmacokinetics of the study drug. Liver-or kidney disease with SGOT, GPT, g-GT, AP, bilirubin and creatinin or above 200% of standard. Patients, who are not sufficiently compliant, or patients, who are not capable or willing to appear for controlling vistas. Presumed risk of transmission of HIV or hepatitis via blood from the participant