Ventilatory control in peripheral chemoreceptor-denervated ponies during chronic hypoxemia.
Abstract: The present study was designed to provide further insight into the role of the carotid and aortic chemoreceptors in ventilatory (VE) acclimatization during sojourn at altitude. Measurements were made: 1) on 10 ponies near sea level (SL, 740 Torr) under normal conditions, 2) on 6 of these at SL following chemoreceptor denervation (CD), and 3) subsequently on all 10 during 4 days of hypobaric hypoxia (PaO2 = 40-47 Torr). CD resulteo in hypoventilation at SL (deltaPaCO2 = d8 Torr, P less than 0.05), and it prevented hyperventilation normally observed with injection of NaCN and acute exposure to hypoxia (less than 1 h). In contrast, hyperventilation was evident in normal ponies during acute hypoxia (deltaPaCO2 = -6.7 Torr). Ventilation increased in both groups between the 2nd and 8th h of hypoxia (deltaPaCO2 from 1 h = -4 Torr, P less than 0.05). This change, a common characteristic of acclimatization, persisted throughout 4 days of hypoxia in the normal ponies. However, in the CD ponies this change was evident consistently only through the 12th h and after the 44 h hyperventilation was no longer evident. We conclude that the peripheral chemoreceptors are essential in ponies for normal VE acclimatization to this degree of hypoxemia. Two additional findings in CD ponies suggest the presence of a CNS inhibitory influence on the VE control center during chronic hypoxemia. First, acute hyperoxygenation on the 4th day of hypoxemia induced hyperventilation (deltaPaCO2 = -5 Torr, P less than 0.05). Second, again on the 4th day and during hyperoxygenation, VE responsiveness to CO2 and doxapram HCl was greater than at sea level.
Publication Date: 1976-12-01 PubMed ID: 1002641DOI: 10.1152/jappl.1976.41.6.878Google Scholar: Lookup
The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Journal Article
- Research Support
- U.S. Gov't
- P.H.S.
Summary
This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.
This research aimed to analyze the function of carotid and aortic chemoreceptors, which are key elements in ventilatory acclimatization, especially during high altitude exposure. The study found that these chemoreceptors are crucial for normal ventilatory adjustment in ponies subjected to sustained low oxygen conditions or hypoxemia.
Methodology
- The study was conducted on ten ponies at sea level under normal conditions, with six of them undergoing chemoreceptor denervation and all examined during four days of hypobaric hypoxia- a condition mimicking high altitude exposure.
- The ponies’ ventilation responses were observed and measured at each of these stages.
Findings
- Chemoreceptor denervation resulted in hypoventilation in ponies at sea level. This process also prevented the usual hyperventilation seen with NaCN injection and with sudden exposure to hypoxia (less than 1 hour).
- However, normal ponies did exhibit hyperventilation during sudden hypoxia.
- Both denervated and normal ponies showed increased ventilation during the second to eighth hours of hypoxia, i.e., the first stages of acclimatization.
- This increased ventilation persisted in normal ponies through four days of hypoxia, showing sustained acclimatization. However, in denervated ponies, this state lasted only through the twelfth hour, after which there was no evidence of sustained hyperventilation.
Conclusions
- The findings suggest that peripheral chemoreceptors (carotid and aortic) are critical for ponies to adapt ventilatory function during chronic hypoxemia effectively.
- Additional findings in denervated ponies pointed to a probable inhibitory influence on the ventilatory control center in the central nervous system during sustained hypoxia. Signs of this influence included heightened ventilation responses to hyperoxygenation on the fourth day and greater ventilation reactivity to CO2 and doxapram HCl (a respiratory stimulant) during hyperoxygenation.
These insights indicate the vital role of chemoreceptors in ventilatory acclimatization and the possible existence of central nervous system components that contribute to ventilation control during long-term hypoxia.
Cite This Article
APA
Forster HV, Bisgard GE, Rasmussen B, Orr JA, Buss DD, Manohar M.
(1976).
Ventilatory control in peripheral chemoreceptor-denervated ponies during chronic hypoxemia.
J Appl Physiol, 41(6), 878-885.
https://doi.org/10.1152/jappl.1976.41.6.878 Publication
Researcher Affiliations
MeSH Terms
- Acclimatization
- Acid-Base Equilibrium
- Altitude
- Animals
- Aortic Bodies / physiology
- Aortic Bodies / physiopathology
- Carbon Dioxide
- Carotid Body / physiology
- Carotid Body / physiopathology
- Cerebrospinal Fluid / metabolism
- Chemoreceptor Cells / physiology
- Chemoreceptor Cells / physiopathology
- Doxapram / pharmacology
- Horses / physiology
- Hypoxia / physiopathology
- Oxygen
- Oxygen Consumption
- Paraganglia, Nonchromaffin / physiology
- Respiration / drug effects
Citations
This article has been cited 11 times.- Buchholz KJ, Burgraff NJ, Neumueller SE, Hodges MR, Pan LG, Forster HV. Physiological and neurochemical adaptations following abrupt termination of chronic hypercapnia in goats.. J Appl Physiol (1985) 2021 Apr 1;130(4):1259-1273.
- Hoiland RL, Howe CA, Coombs GB, Ainslie PN. Ventilatory and cerebrovascular regulation and integration at high-altitude.. Clin Auton Res 2018 Aug;28(4):423-435.
- Pamenter ME, Powell FL. Time Domains of the Hypoxic Ventilatory Response and Their Molecular Basis.. Compr Physiol 2016 Jun 13;6(3):1345-85.
- Fatemian M, Herigstad M, Croft QP, Formenti F, Cardenas R, Wheeler C, Smith TG, Friedmannova M, Dorrington KL, Robbins PA. Determinants of ventilation and pulmonary artery pressure during early acclimatization to hypoxia in humans.. J Physiol 2016 Mar 1;594(5):1197-213.
- Hodges MR, Forster HV. Respiratory neuroplasticity following carotid body denervation: Central and peripheral adaptations.. Neural Regen Res 2012 May 15;7(14):1073-9.
- Pamenter ME, Carr JA, Go A, Fu Z, Reid SG, Powell FL. Glutamate receptors in the nucleus tractus solitarius contribute to ventilatory acclimatization to hypoxia in rat.. J Physiol 2014 Apr 15;592(8):1839-56.
- Wilkinson KA, Huey K, Dinger B, He L, Fidone S, Powell FL. Chronic hypoxia increases the gain of the hypoxic ventilatory response by a mechanism in the central nervous system.. J Appl Physiol (1985) 2010 Aug;109(2):424-30.
- Blain GM, Smith CA, Henderson KS, Dempsey JA. Peripheral chemoreceptors determine the respiratory sensitivity of central chemoreceptors to CO(2).. J Physiol 2010 Jul 1;588(Pt 13):2455-71.
- Smith CA, Forster HV, Blain GM, Dempsey JA. An interdependent model of central/peripheral chemoreception: evidence and implications for ventilatory control.. Respir Physiol Neurobiol 2010 Oct 31;173(3):288-97.
- McMurphy RM, Cribb PH. Alleviation of postanesthetic hypoxemia in the horse.. Can Vet J 1989 Jan;30(1):37-41.
- Dempsey JA, Forster HV, Bisgard GE, Chosy LW, Hanson PG, Kiorpes AL, Pelligrino DA. Role of cerebrospinal fluid [H+] in ventilatory deacclimatization from chronic hypoxia.. J Clin Invest 1979 Jul;64(1):199-205.
Use Nutrition Calculator
Check if your horse's diet meets their nutrition requirements with our easy-to-use tool Check your horse's diet with our easy-to-use tool
Talk to a Nutritionist
Discuss your horse's feeding plan with our experts over a free phone consultation Discuss your horse's diet over a phone consultation
Submit Diet Evaluation
Get a customized feeding plan for your horse formulated by our equine nutritionists Get a custom feeding plan formulated by our nutritionists
