Despite a focus on P2X receptors (Rs), new data have shown that inspiratory rhythm generating networks in the Pre-Bötzinger complex are very sensitive to P2Y1R modulation. Here we used nerve and whole cell recording in rhythmic and non-rhythmic medullary slices of neonatal rat to assess the effect of P2YR signaling on XII inspiratory activity and motoneuron (MN) properties respectively. Local application of UTP (1-10 mM; agonist at P2Y2,4,6,11-14) to the XII nucleus evoked tonic discharge in XII nerve and a small but significant increase (<20%) in burst amplitude. UTP (1 mM) also evoked slow inward currents (150-±30pA, n=11) that reversed near EK+, and increased input resistance by 15±5%. Local application of P2Y1R agonists 2MeSADP (1-10mM) and MRS2365 (0.1-1mM) to the XII nucleus also evoked tonic discharge but a 30-50% increase in burst amplitude. P2Y1R involvement was further supported by P2Y1R immunolabeling and slow onset, small amplitude 2MeSADP-evoked (1-10mM) inward currents (43±21 pA, n=6) that reversed near EK+ (3/6 MNs). Data indicate functional P2YRs on XII MNs. Despite UTP currents that were 4-fold greater than P2Y1R currents, P2Y1R agonists appear to have had larger effects on XII inspiratory burst amplitude. P2Y1R may be preferentially distributed to inspiratory XII MNs. [ABSTRACT FROM AUTHOR]