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Rabbit Ventilatory Responses to Peripheral Chemoexcitators: Effects of Chronic Hypoxia

  • Julio AlcayagaEmail author
  • Rodrigo Del Rio
  • Esteban A. Moya
  • Matías Freire
  • Rodrigo Iturriaga
Conference paper
Part of the Advances in Experimental Medicine and Biology book series (AEMB, volume 758)

Abstract

Exposure to prolonged hypobaric hypoxia increases baseline ventilation and the ventilatory response to acute hypoxia, a phenomenon known as hypoxic ventilatory acclimatization (HVA). It is currently accepted that the carotid bodies and the reduced PO2 levels are key elements in the generation of the HVA. However, because most of these experiments have been performed in hypobaric conditions, we studied the effects of 15 days of chronic normobaric hypoxia (CNH) on the rabbit ventilatory responses to hypoxia and chemoexcitatory molecules. New Zealand White rabbits were placed in a 0.3 m³ chamber with controlled temperature and a mean O2 content of 9.17 ± 0.09 %. Animals with or without CNH exposition (naïve) were anesthetized (ketamine/xylazine 75/7.5 mg/kg, i.m.), cannulated and air flow was measured. In naïve animals hypoxic challenges and NaCN increase ventilation, effect completely abolished after bilateral chemodenervation. However, ventilatory responses to nicotine, ATP and dopamine remained largely unchanged after bilateral chemodenervation, suggesting a centrally mediated effect for these drugs. Basal ventilation was reduced in CNH animals, but the dose dependent ventilatory increases induced by NaCN presented an increased sensibility. Further experiments are needed to elucidate the mechanisms responsible for these acclimatized responses.

Keywords

Chronic hypoxia Ventilatory acclimatization Ventilatory reflexes Acetylcholine ATP Dopamine Cyanide 

Notes

Acknowledgements

Study supported by Grant 1090157 from the Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT), Chile.

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Copyright information

© Springer Science+Business Media Dordrecht 2012

Authors and Affiliations

  • Julio Alcayaga
    • 1
    Email author
  • Rodrigo Del Rio
    • 2
  • Esteban A. Moya
    • 2
  • Matías Freire
    • 1
  • Rodrigo Iturriaga
    • 2
  1. 1.Laboratorio de Fisiología Celular, Facultad de CienciasUniversidad de ChileSantiagoChile
  2. 2.Laboratorio de Neurobiología, Facultad de Ciencias BiológicasP Universidad Católica de ChileSantiagoChile

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