We used high resolution optical mapping for the study of changes of activation sequence of a rabbit sinoatrial node induced by adrenergic stimulation during natural and paced rhythm. Activation of adrenoreceptors with isoproterenol (10, 100 nanoM, 1 microM) as well as stimulation of intramural postganglionic sympathetic nerves caused pacemaker migration within sinoatrial node and increase of the rate of generation of excitation. Pacemaker migration in cases of pronounced acceleration of rhythm could proceed in two stages. Termination of adrenergic influences has been followed by restoration of initial chronotopography of excitation of sinoatrial node.