Faculty Collaboration Database

Carotid body denervation alters ventilatory responses to ibotenic acid injections or focal acidosis in the medullary raphe. J Appl Physiol (1985) 2005 Apr;98(4):1234-42

Date

12/08/2004

Pubmed ID

15579571

DOI

10.1152/japplphysiol.01011.2004

Scopus ID

2-s2.0-15444374658 (requires institutional sign-in at Scopus site)   37 Citations

Abstract

Our aim was to determine the effects of carotid body denervation (CBD) on the ventilatory responses to focal acidosis and ibotenic acid (IA) injections into the medullary raphe area of awake, adult goats. Multiple microtubules were chronically implanted into the midline raphe area nuclei either before or after CBD. For up to 15 days after bilateral CBD, arterial PCO2 (PaCO2) (13.3 +/- 1.9 Torr) was increased (P < 0.001), and CO2 sensitivity (-53.0 +/- 6.4%) was decreased (P <0.001). Thereafter, resting PaCO2 and CO2 sensitivity returned (P <0.01) toward control, but PaCO2 remained elevated (4.8 +/- 1.9 Torr) and CO2 sensitivity reduced (-24.7 +/- 6.0%) > or =40 days after CBD. Focal acidosis (FA) at multiple medullary raphe area sites 23-44 days post-CBD with 50 or 80% CO(2) increased inspiratory flow (Vi), tidal volume (Vt), metabolic rate (VO2), and heart rate (HR) (P <0.05). The effects of FA with 50% CO2 after CBD did not differ from intact goats. However, CBD attenuated (P <0.05) the increase in Vi, Vt, and HR with 80% CO2, but it had no effect on the increase in VO2. Rostral but not caudal raphe area IA injections increased Vi, BP, and HR (P < 0.05), and these responses were accentuated (P <0.001) after CBD. CO2 sensitivity was attenuated (-20%; P <0.05) <7 days after IA injection, but thereafter it returned to prelesion values in CBD goats. We conclude the following: 1) the attenuated response to FA after CBD provides further evidence that the carotid bodies provide a tonic facilitory input into respiratory control centers, 2) the plasticity after CBD is not due to increased raphe chemoreceptor sensitivity, and 3) the "error-sensing" function of the carotid body blunts the effect of strong stimulation of the raphe.

Author List

Hodges MR, Opansky C, Qian B, Davis S, Bonis JM, Krause K, Pan LG, Forster HV

Authors

Hubert V. Forster PhD Professor in the Physiology department at Medical College of Wisconsin
Matthew R. Hodges PhD Professor in the Physiology department at Medical College of Wisconsin

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

Acidosis
Adaptation, Physiological
Animals
Carotid Body
Denervation
Female
Goats
Ibotenic Acid
Male
Orchiectomy
Oxygen
Pulmonary Ventilation
Raphe Nuclei