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Ventilatory and central neurochemical reorganisation of O2 chemoreflex after carotid sinus nerve transection in rat.
- Source :
-
The Journal of physiology [J Physiol] 2000 Feb 01; Vol. 522 Pt 3, pp. 493-501. - Publication Year :
- 2000
-
Abstract
- 1. The first step of this study was to determine the early time course and pattern of hypoxic ventilatory response (HVR) recovery following irreversible bilateral carotid sinus nerve transection (CSNT). The second step was to find out if HVR recovery was associated with changes in the neurochemical activity of the medullary catecholaminergic cell groups involved in the O2 chemoreflex pathway. 2. The breathing response to acute hypoxia (10% O2) was measured in awake rats 2, 6, 10, 45 and 90 days after CSNT. In a control group of sham-operated rats, the ventilatory response to hypoxia was principally due to increased respiratory frequency. There was a large reduction in HVR in the CSNT compared to the sham-operated rats (-65%, 2 days after surgery). Within the weeks following denervation, the CSNT rats progressively recovered a HVR level similar to the sham-operated rats (-37% at 6 days, -27% at 10 days, and no difference at 45 or 90 days). After recovery, the CSNT rats exhibited a higher tidal volume (+38%) than the sham-operated rats in response to hypoxia, but not a complete recovery of respiratory frequency. 3. Fifteen days after CSNT, in vivo tyrosine hydroxylase (TH) activity had decreased in caudal A2C2 (-35%) and A6 cells (-35%). After 90 days, the CSNT rats displayed higher TH activity than the sham-operated animals in caudal A1C1 (+51%), caudal A2C2 (+129%), A5 (+216%) and A6 cells (+79%). 4. It is concluded that HVR following CSNT is associated with a profound functional reorganisation of the central O2 chemoreflex pathway, including changes in ventilatory pattern and medullary catecholaminergic activity.
- Subjects :
- Animals
Body Weight physiology
Brain Stem enzymology
Brain Stem physiology
Denervation
Hyperventilation blood
Hyperventilation physiopathology
Male
Pulmonary Ventilation physiology
Rats
Rats, Sprague-Dawley
Recovery of Function physiology
Tidal Volume physiology
Time Factors
Tyrosine 3-Monooxygenase metabolism
Wakefulness physiology
Carotid Body physiology
Carotid Sinus innervation
Carotid Sinus physiology
Hypoxia physiopathology
Respiration
Subjects
Details
- Language :
- English
- ISSN :
- 0022-3751
- Volume :
- 522 Pt 3
- Database :
- MEDLINE
- Journal :
- The Journal of physiology
- Publication Type :
- Academic Journal
- Accession number :
- 10713972
- Full Text :
- https://doi.org/10.1111/j.1469-7793.2000.t01-4-00493.x