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Effect of intermittent hypercapnia on respiratory control in rat pups

Justin A Steggerda1, Catherine A Mayer, Richard J Martin

  • 1Department of Pediatrics, Case Western Reserve University, Cleveland, Ohio, USA.

Neonatology
|September 16, 2009
PubMed

Insights

Daily exposure to intermittent hypercapnia in neonatal rats enhances their ventilatory response to hypoxia. This suggests altered neonatal respiratory control, impacting preterm infant development.

Area of Science:

  • Neonatal physiology
  • Respiratory control mechanisms
  • Chemoreceptor function

Background:

  • Preterm infants experience blood gas instability due to immature respiratory control.
  • Intermittent hypoxia in early life increases chemoreceptor sensitivity and breathing pattern instability.
  • The effects of intermittent hypercapnia on neonatal respiratory control are not well understood.

Purpose of the Study:

  • To investigate the effects of intermittent hypercapnia on respiratory control in neonatal rat pups.
  • To test the hypothesis that intermittent hypercapnia alters ventilatory responses to subsequent hypercapnic and hypoxic challenges.
  • To understand potential implications for respiratory regulation in vulnerable neonates.

Main Methods:

  • Neonatal rat pups (postnatal days 7-14) were exposed daily to cycles of intermittent hypercapnia (5% CO2) and normoxia for one week.
  • Diaphragm electromyograms (EMGs) were analyzed to assess ventilatory responses.
  • Pups were subjected to subsequent acute hypercapnic (5% CO2) and hypoxic (12% O2) challenges.

Main Results:

  • Intermittent hypercapnia exposure did not significantly alter the ventilatory response to a subsequent hypercapnic challenge.
  • Neonatal rats exposed to intermittent hypercapnia showed an enhanced ventilatory response to hypoxic challenge (118% of baseline EMG).
  • Control pups exhibited a smaller increase in ventilatory response to hypoxia (107% of baseline EMG).

Conclusions:

  • Prior intermittent hypercapnia exposure in neonatal rats perturbs respiratory control.
  • This perturbation manifests as an enhanced ventilatory response to subsequent hypoxia.
  • The findings suggest a potential role for peripheral chemoreceptor sensitization, impacting neonatal respiratory regulation.

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