[1] Univ Halle Wittenberg, Cell Physiol Grp, Fac Med, D-06112 Halle An Der Saale, Germany
[2] Univ Lubeck, Inst Physiol, Lubeck, Germany
[3] Walter & Eliza Hall Inst Med Res, Melbourne, Vic 3050, Australia
[4] Univ Zurich, Inst Physiol, CH-8006 Zurich, Switzerland