Title: Effect of isomazole on the responsiveness to calcium of the contractile elements in skinned cardiac muscle fibres of various species
Abstract: We report here that the new cardiotonic agent isomazole increases the Ca2+ responsiveness of skinned myocardial fibres from different species. Isomazole (0.01-1 mM) increased the half-maximal, Ca2+-activated force development in atrial fibres from humans and in ventricular fibres from pigs, monkeys, guinea-pigs and rats in a concentration-dependent manner. The maximal force development was also increased in fibres from all species except pig. Isomazole shifted force-calcium curves to the left and enhanced maximal force as demonstrated for guinea-pig and human fibres, indicating increases in both calcium sensitivity and maximum force-generating capability of the contractile apparatus. In guinea-pig tissue, the concentration dependence for the activation of skinned fibres was similar to that for the positive inotropic effect in papillary muscle. These results suggest a direct effect of isomazole on contractile proteins, but the degree to which this effect contributes to the overall positive inotropic action of isomazole remains to be determined.
Publication Year: 1988
Publication Date: 1988-01-01
Language: en
Type: article
Indexed In: ['crossref', 'pubmed']
Access and Citation
Cited By Count: 28
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