Postnatal development of ATP signaling involved in respiratory response to hypoxia in rats.

Abstract

In adults, ATP, acting through P2X receptors, plays an important role in both carotid body excitation and brainstem respiratory stimulation during hypoxia. In this study, we addressed whether the contributions of P2X receptors undergo developmental changes in newborn, during which the hypoxic ventilatory response (HVR) matures. Using whole body plethysmography, HVR was measured in rats at 1, 4, 7, 12 and 21 postnatal days before and after intraperitoneal injection of suramin (P2X receptor antagonist, 40mg/kg) or vehicle. At each age, suramin reduced breathing frequency but not tidal volume (p<0.05, suramin vs vehicule group). The reduction in frequency was age dependent with greater effect at older ages (p<0.05). Using single‐unit recordings of carotid body activity, in vitro, suramin depressed discharge activity in both normoxia (150 torr PO2) and hypoxia (60 torr PO2), but the magnitude of depression was not age dependent. We conclude that ATP acting through P2X receptors plays an important role, both peripherally and centrally, in the HVR and this undergoes a developmental increase in the newborn period. These developmental changes primarily occur centrally. Founded PF‐RSR du FRSQ, IRSC.