The shift of the leading pacemaker site within the sinoatrial node (SAN) may act as a mechanism of the sinus rhythm (SR) modulation. However, conventional methods of myocardium mapping do not allow to observe beat-to-beat changes in the SAN activation sequence. Therefore, we applied high-resolution optical mapping technique to register beat-to-beat changes in the SAN activation pattern during cholinergic and adrenergic influence. Acetylcholine (10 mM) or stimulation of the intramural parasympathetic nerves caused slowing of the SR as well as pacemaker shift (PS) and formation of inexcitable region in the central part of the SAN. The latter effect may be one of the reasons of the PS. The slowing of the SR, which exceeded 12.83.1 % of the control rate of the SR, was always accompanied with PS. Isoproterenol (10 nM–1 mM) or stimulation of sympathetic postganglionic nerves also evoked the PS, but without formation of the inexcitable zone. The acceleration of the SR by more than 10.51.3 % of the control rate of the rhythm, always coincided with PS. Thus, either cholinergic or adrenergic factors cause PS in the rabbit SAN. Modest changes of the SR does not coincide with PS, but greater changes are always accompanied by the shift and may be due to it, according to one of the hypothesis. Formation of inexcitable zone at the site of the basic leading pacemaker location seems to be one of the mechanisms of the PS, but not the only.