After 15 minutes of rest the first bood samples are taken. An infusion 3 ml/kg bodyweight Albumin 20% is given during 30 minutes. The first hour after study start (start of infusion) blood samples are taken every 10 minutes. The following 4 hours another 9 blood samples are collected. Hemoglobin, albumin and colloidosmotic pressure will be measured at every occasion.