1. From the Institute of Physiology I, Life and Brain Center, Medical Faculty (M.H., A.B., K.K., N.V., B.K.F.), University of Bonn, Germany.
2. Institute of Physiology II (M.D., V.S.), University of Bonn, Germany.
3. Pharma Center Bonn (B.K.F.), University of Bonn, Germany.