Peracute Myocardial Infarction: Features of the Influence of [[alpha].sub.2]-Adrenoreceptor Stimulation on the Isolated Heart

We performed a comparative analysis of the effect of [[alpha].sub.2]-adrenoreceptor stimulation on the performance of Langendorff-isolated heart from rats with experimental myocardial infarction in the acute stage and sham-operated animals (control). In animals with peracute myocardial infarction, different agonist concentrations (clonidine, [10.sup.-6] and [10.sup.-9] M) produced a multidirectional effect on the left-ventricular developed pressure and speed and time parameters of heart contractility. In control rats, both concentrations of the agonist added to the perfused solution reduced contraction force. Clonidine in a concentration of [10.sup.-6] M reduced HR in both groups and in a concentration of [10.sup.-9] M, it decreased HR in control rats and caused multidirectional changes in rats with myocardial infarction. The coronary flow decreased in all series of experiments. Key Words: model of myocardial infarction; isolated heart; rat