FMD will be performed by measuring increase of diameter of the brachial artery above the elbow before and after interruption of circulation to the forearm for a period of 5 minutes by use of a tourniquet placed below the elbow. Flow through the brachial artery will be recorded immediately after circulation is restored for 15 s. Dilation will be expressed as a ratio relative to the diameter prior to interruption in percent. Blood samples will be analyzed for GP content and metabolites at KVL.