Peracute Myocardial Infarction: Features of the Influence of α-Adrenoreceptor Stimulation on the Isolated Heart.

We performed a comparative analysis of the effect of α-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 and 10 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.

Features of α-Adrenergic Regulation of Isolated Rat Heart after Hypokinesia.

We studied the effect of the α-adrenergic receptor agonist clonidine hydrochloride (10-10 M) on the isolated heart of adult rats after 30-day restriction of motor activity. In hypokinetic rats, in comparison with control animals, clonidine caused a positive inotropic effect; the dynamics of coronary flow was changed after stimulation of α-adrenergic receptors by clonidine in the minimum and maximum concentrations. Moreover, clonidine in concentrations of 10 and 10 M reduced coronary flow both in the control group and against the background of hypokinesia.

α-Adrenergic Receptor Blockade Inhibits Langendorff-Isolated Rat Heart Work.

We studied the effect of selective α-adrenergic receptor antagonist JP-1302 in concentrations of 10-10 M on inotropy, chronotropy, and coronary flow in the Langendorff-isolated rat heart. JP-1302 in all studied concentrations decreased the left-ventricular myocardium force contraction, HR, and coronary flow. The maximum inotropic, chronotropic, and vascular effects were observed when the antagonist was applied to the perfused solution in a concentration of 10 M.

The Effect of α-Adrenoreceptors Blockade on the Isolated Rat Heart during the Formation of Sympathetic Innervation.

We studied the effects of the α-adrenergic receptor antagonist yohimbine (10-10 M) on inotropy, chronotropy, and coronary flow in the Langendorff-isolated heart from 3- and 6-week-old rats. Yohimbine affected all the studied functional parameters of the isolated heart. The force of contraction of the left ventricular myocardium, HR, and coronary flow decreased at all studied concentrations of the antagonist.

Response of Isolated Rat Heart to α-Adrenergic Receptor Stimulation after I Current Blockade in the Late Postinfarction Period.

We studied the effect of α-adrenoreceptor activation after preliminary I-current blockade on the performance of the Langendorff-isolated rat heart 54 days after modeling myocardial infarction. Stimulation of α-adrenoreceptors against the background of application of I blocker ZD7288 in concentrations of 10 and 10 M decreased myocardial inotropy in isolated rat hearts by 50 and 39% (p<0.05) and increased HR by 20 and 15% (p<0.