Calcium-dependent toxic effects of digoxin in isolated myocardial preparations
Wagner, J.; Salzer, W.W.
Archives Internationales de Pharmacodynamie et de Therapie 223(1): 4-14
1976
ISSN/ISBN: 0003-9780 PMID: 999401 Document Number: 100610
On isolated guinea-pig papillary muscles as well as on electrically driven atria digoxin was infused into the bath fluid until cardiac arrest occurred. The concentration of digoxin which caused standstill is defined as the toxic one. The toxicity was determined under various Ca2+-concentrations. On the papillary muscle the increase of extracellular Ca2+ from 0.9 to 7.2 mM increased the toxicity of digoxin, i.e. significantly diminished its toxic concentrations. Likewise, on electrically driven atria an increase of Ca2+ from 0.45 to 7.2 mM increased the toxicity of digoxin. These results demonstrate that with regard to the toxicity Ca2+ and digoxin act synergistically.