Age-dependent chemosensitive pontine inhibition of medullary respiratory rhythm generation in the isolated brainstem of the neonatal rat

Age-dependence and chemosensitivity of the pontine inhibitory effect on medullary respiratory rhythm generation were examined in the isolated brainstem-spinal cord of the neonatal rat. In early preparations (days 1-2), the increase in RR (ΔRR) induced by the pons resection was larger in 8% CO₂ (pH 7.2) than in 2% CO₂ (pH 7.8). That difference was not found in late preparations (days 3-4). Under a given pH, the ΔRR was larger in early preparations than in late preparations.