MRI based arterial spin labeling is a noninvasive assessment not using contrast agents to measure the functional parameters of the kidney. This is avoiding serious complications such as acute kidney failure and nephrogenic systemic fibrosis. There is no known negative impact to the patient. In addition we now want to analyze the validity of this MRI‐technique by provoking acutely changes of renal plasma flow. As a further provocative maneuver we selected the cold pressor test as a physiological stress test. Forehead cooling activates the sympathetic nervous system and increases blood pressure and heart rate by causing pain. This mechanism has got an impact on renal haemodynamics. To minimize the possible cold injuries we use the 1°C ice water pack only for 60 seconds and avoid the contact to the eyes.