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Rezumat articol ediţie STUDIA UNIVERSITATIS BABEÅž-BOLYAI
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Rezumat: The Effect of Digoxin on Some Parameters of the Contraction of Ventricular Myocardium in Frog. The role of digoxin in affecting transmembrane calcium fluxes is well established in mammalian cardiac myocytes. In order to see whether digoxin also induces calcium-related effects on ventricular parameters in ectotherms, we performed the present experiments on isolated frog hearts by means of a previously presented data acquisition system. Taking into consideration that the digoxin-induced calcium disturbances would be reflected mainly in changes of the ventricular contractility, we have measured its classical parameters – contraction amplitude, contraction period, contraction plateau and relaxation period, as well as some original ones, such as contraction velocity, force, mechanical work and heart power. Our results are consistent with those obtained by others in mammalian hearts and demonstrate that digoxin has a positive inotropic effect on the frog ventricle. Thus, all the parameters mentioned above showed significant initial increases, followed by their stabilisation above the basic values during the second and the third time intervals. In terms of cardiac frequency, we have established a severe bradycardia which was not observed in mammals. Therefore, the conclusion of our study is that, like in mammals, digoxin affects the mechanical activity of the frog hearts, and its inotropic and chronotropic effects are probably due to changes induced by this agent in the calcium activity. |
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