1. Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Casilla 70058, Santiago‐7, Chile
2. Centro de Estudios Científicos (CECS), Casilla 1469, Valdivia, Chile
3. August Krogh Institute, University of Copenhagen, 13 Universitetsparken, 2100 Copenhagen Ø, Denmark
4. IMB, Department of Physiology and Pharmacology, Southern Danish University, Odense, Denmark