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Carotid body noradrenergic sensitivity in ventilatory acclimatization to hypoxia. Respir Physiol 1993 Apr;92(1):77-90 PMID: 8390087

Pubmed ID

8390087

Abstract

Norepinephrine inhibits ventilation in awake goats under normoxic, resting conditions. This inhibition is carotid body (CB) mediated and may be due to stimulation of noradrenergic receptor on the CB. Cao et al. (FASEB J. A118, 1991) recently suggested that CB noradrenergic receptors may be down regulated following 24-36 hours of hypoxic exposure in cats. Our study was aimed at determining whether a change in noradrenergic receptor sensitivity during ventilatory acclimatization to hypoxia (VAH) was responsible for the increased sensitivity of the CB to hypoxia during prolonged exposure to hypoxia in goats. We tested this hypothesis using intracarotid infusions of norepinephrine (NE) (0.5, 1.0, 5.0 micrograms.kg-1.min-1) and dopamine (DA) (1.0 micrograms.kg-1.min-1) in awake goats under control normoxic conditions, during 4 h of isocapnic hypoxia, and upon return to normoxia. NE and DA (1.0 micrograms.kg-1.min-1) both inhibited control ventilation significantly during the intracarotid infusions (56% and 62% decreases, respectively). No significant differences were found between the pre- and post-hypoxic infusions of NE and DA in normoxia. During hypoxia, inhibition of VE during NE and DA infusions was attenuated relative to control. Time-dependent change of the NE response were not apparent during the acclimatization period suggesting that a decreased carotid body chemoreceptor sensitivity to NE and DA is not responsible for the increased drive to breathe characteristic of ventilatory acclimatization to hypoxia.

Author List

Ryan ML, Hedrick MS, Pizarro J, Bisgard GE

Author

Melinda R. Dwinell PhD Center Associate Director, Associate Professor in the Physiology department at Medical College of Wisconsin




Scopus

2-s2.0-0027469614   23 Citations

MESH terms used to index this publication - Major topics in bold

Acclimatization
Animals
Blood Pressure
Carbon Dioxide
Carotid Body
Dopamine
Dose-Response Relationship, Drug
Goats
Heart Rate
Hydrogen-Ion Concentration
Norepinephrine
Oxygen
Oxygen Consumption
Receptors, Adrenergic
Respiration
Tidal Volume
jenkins-FCD Prod-296 4db9d02597e0a2e889e230f853b641c12f1c3ee3