Affiliation: | (1) Department of Pharmacology, University of Essen, Hufelandstraße 55, D-4300 Essen 1;(2) Ruhrlandklinik Essen-Heidhausen, Tüschener Weg 40, D-4300 Essen 16, Federal Republic of Germany;(3) Present address: Department of Pediatric Cardiology, University of Essen, Hufelandstr. 55, D-4300 Essen 1, Federal Republic of Germany |