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Chronic hypoxia enhances the phrenic nerve response to arterial chemoreceptor stimulation in anesthetized rats. J Appl Physiol (1985) 1999 Aug;87(2):817-23 PMID: 10444644

Pubmed ID

10444644

Abstract

Chronic exposure to hypoxia results in a time-dependent increase in ventilation called ventilatory acclimatization to hypoxia. Increased O(2) sensitivity of arterial chemoreceptors contributes to ventilatory acclimatization to hypoxia, but other mechanisms have also been hypothesized. We designed this experiment to determine whether central nervous system processing of peripheral chemoreceptor input is affected by chronic hypoxic exposure. The carotid sinus nerve was stimulated supramaximally at different frequencies (0.5-20 Hz, 0.2-ms duration) during recording of phrenic nerve activity in two groups of anesthetized, ventilated, vagotomized rats. In the chronically hypoxic group (7 days at 80 Torr inspired PO(2)), phrenic burst frequency (f(R), bursts/min) was significantly higher than in the normoxic control group with carotid sinus nerve stimulation frequencies >5 Hz. In the chronically hypoxic group, peak amplitude of integrated phrenic nerve activity ( integral Phr, percent baseline) or change in integral Phr was significantly greater at stimulation frequencies between 5 and 17 Hz, and minute phrenic activity ( integral Phr x f(R)) was significantly greater at stimulation frequencies >5 Hz. These experiments show that chronic hypoxia facilitates the translation of arterial chemoreceptor afferent input to ventilatory efferent output through a mechanism in the central nervous system.

Author List

Dwinell MR, Powell FL

Author

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




Scopus

2-s2.0-0032841030   84 Citations

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

Acclimatization
Anesthesia
Animals
Blood Pressure
Carotid Sinus
Chemoreceptor Cells
Electric Stimulation
Hypoxia
Neurons, Afferent
Neurons, Efferent
Phrenic Nerve
Pulmonary Ventilation
Rats
Rats, Sprague-Dawley
Vagotomy
jenkins-FCD Prod-300 626508253d14e4184314fb9f66322a03a5906796