Reviews of Physiology Biochemistry and Pharmacology 133. Editors: M. P. Blaustein, R. Greger, H. Grunicke, R. Jahn, W. J. Lederer, L. M. Mendell, A. Miyajima, D. Pette, G. Schultz, M. Schweiger. With 18 Figures and 5 Tables.