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 med ullary respiratory rhythm generation were examined in the isolated brainste m-spinal cord of the neonatal rat. In early preparations (days 1-2), the in crease in RR (Delta RR) induced by the pens resection was larger in 8 % CO2 (pH 7.2) than in 2% CO2 (pH 7.8). That difference was not found in late pr eparations (days 3-4). Under a given pH, the Delta RR was larger in early p reparations than in late preparations. (C) 2000 Elsevier Science B.V. All r ights reserved.