The effect of stimulation of the adrenergic receptors on the frequency depression of the temporal parameters of the action potential in the right atrium of rats]

At a stimulation rate of 1 Hz, activation of alpha-adrenoreceptors prolonged the AP duration at 10%, 50%, and 90% repolarisation at 10(-7), 10(-6) M in the rat isolated right atria, but shortened it at a higher concentration of 10(-5) M. The frequency-induced depression of the AP duration became more evident in cardiomyocytes stimulated by 10(-7), 10(-6) M and less obvious at 10(-5) M of alpha-adrenoagonist. Activation of alpha-adrenoreceptors by isoprenalin shortened the AP duration and enhanced the stimulation-rate-dependent changes in the atrial AP configuration.