Inclusion criteria:  Participants are eligible if they can provide informed consent and meet the following criteria:  Healthy men and women aged 20-60 years. Five participants of each gender are required in study II, whereto, gender is not of importance in study I. Healthy is defined as no use of medicine besides from contraceptives and vitamins.  Exclusion criteria:  The participants are not eligible if they fulfill any of the following criteria:  Exclusion criteria for the MRI are contraindication to MRI such as claustrophobia or the presence of a pacemaker or other implanted metallic device.  Persons with circumference including arms > 160 cm. (MR scanner bore size) Pregnant women are not allowed to volunteer.