The Role of α-Adrenergic Receptors in the Regulation of Electrical Activity of Right Atrial Myocardiocytes from 21-Day-Old Rats.

We studied the influence of the α-adrenergic receptor agonist methoxamine on the frequency of spontaneous activity and the parameters of electrical activity of the atrial myocardium from 21-day-old rats with normal sinus (preserved sinus node) or paced rhythm. Stimulation with methoxamine increased the frequency of spontaneous activity. Under the conditions of preserved sinus rhythm, the α-adrenergic agonist decreased the duration of the repolarization phase of the action potential, whereas at paced rhythm, this parameter increased.