Previous studies have shown that the sympathetically mediated oscillations of arterial pressure (AP), the so-called Mayer waves, are shifted from 0.4 to 0.6 Hz after acute -adrenoceptor blockade in conscious rats. This raises the possibility that, under physiological conditions, Mayer waves are mediated by the conjoint action of both norepinephrine and other sympathetic cotransmitters. To evaluate the possible role of the cotransmitter ATP in determining Mayer wave's frequency, AP and renal sympathetic nerve activity (RSNA) were simultaneously recorded in 10 conscious rats with cardiac autonomic blockade before and after acute blockade of P2 receptors with pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid. P2 receptor blockade did not alter the mean level and overall variability of AP and RSNA but shifted peak coherence between AP and RSNA from 0.43 ± 0.02 to 0.22 ± 0.01 Hz. A model of the sympathetic limb of the arterial baroreceptor reflex was designed to simulate AP Mayer waves at 0.2 and 0.6 Hz, with either norepinephrine or ATP acting as the sole sympathetic cotransmitter, respectively. When both cotransmitters acted in concert, a single oscillation was observed at the frequency of 0.4 Hz when the gain ratio between the adrenergic and purinergic components was set at 15. The model thus accounted for an important role of ATP in determining Mayer wave's frequency while not being involved in sustaining the mean level of AP nor controlling its overall variability.