Effects of hydroxocobalamin on rat cardiac papillary muscle.
Hydroxocobalamin is a rapid and powerful antidote in acute cyanide poisoning. The effects of hydroxocobalamin (0.1, 0.3, and 1 mM) on intrinsic myocardial contractility were studied on isolated rat cardiac papillary muscles (n = 10). Whatever the concentration, hydroxocobalamin did not modify the active isometric force and a slight increase in maximum unloaded shortening velocity was noted at 1 mM. Only 0.3 mM significantly impaired contraction-relaxation coupling under low load, suggesting a slight decrease in sarcoplasmic reticulum function. No changes in contraction-relaxation coupling under heavy load were noted, suggesting the lack of modification of myofilament calcium sensitivity. These results suggest that hydroxocobalamin does not induce noticeable changes in intrinsic myocardial contractility. An indirect mechanism might be involved in the previously reported decrease in cardiac function at supratherapeutic concentrations of hydroxocobalamin.
Beregi
J P
JP
Institut National de la Santé et de la Recherche Médicale U275, LOA-ENSTA-Ecole Polytechnique, Palaiseau, France.
Riou
B
B
Lecarpentier
Y
Y
D000818:Animals; D015220:Calcium Channels / Q000187:drug effects; D003486:Cyanides / Q000506:poisoning; D006439:Hemodynamics / Q000187:drug effects; D006879:Hydroxocobalamin / Q000494:pharmacology* / Q000627:therapeutic use; D009200:Myocardial Contraction / Q000187:drug effects*; D010210:Papillary Muscles / Q000187:drug effects*; D011041:Poisoning / Q000188:drug therapy; D051381:Rats
D015220:Calcium Channels; D003486:Cyanides; D006879:Hydroxocobalamin