title: Contractile proteins: possible targets for the cardiotonic action of MCI-154, a novel cardiotonic agent?
abstract: The effect on the contractile protein system of MCI-154, a novel and potent cardiotonic agent, was examined by using thin bundles of chemically skinned fibers from the guinea-pig papillary muscles. MCI-154 increased the Ca2+ sensitivity of the contractile protein system of the cardiac skinned fibers. Moreover, MCI-154 enhanced the maximum tension developed at pCa 4.4. These results suggest that an increase in responses of the contractile protein system to Ca2+ ion is, at least in part, responsible for the positive inotropic action of MCI-154.
mesh_terms: D000818:Animals; D002316:Cardiotonic Agents; D003285:Contractile Proteins / Q000502:physiology*; D006168:Guinea Pigs; D007093:Imidazoles / Q000494:pharmacology; D066298:In Vitro Techniques; D020105:Milrinone; D009200:Myocardial Contraction / Q000187:drug effects; D010210:Papillary Muscles / Q000187:drug effects; D011724:Pyridazines / Q000494:pharmacology*; D011728:Pyridones / Q000494:pharmacology
chemical_list: D002316:Cardiotonic Agents; D003285:Contractile Proteins; D007093:Imidazoles; D011724:Pyridazines; D011728:Pyridones; C052228:MCI 154; C029758:sulmazole; D020105:Milrinone