scholarly journals Efficacy of Electrical Baroreflex Activation Is Independent of Peripheral Chemoreceptor Modulation

Hypertension ◽  
2020 ◽  
Vol 75 (1) ◽  
pp. 257-264 ◽  
Author(s):  
Karsten Heusser ◽  
Arvo Thöne ◽  
Axel Lipp ◽  
Jan Menne ◽  
Joachim Beige ◽  
...  
Keyword(s):  
Peripheral Chemoreceptor

Decline in peripheral chemoreceptor excitatory stimulation during acute hypoxia in the lamb

1987 ◽  
Vol 63 (2) ◽  
pp. 795-802 ◽  
Author(s):  
J. L. Carroll ◽  
M. A. Bureau
Keyword(s):  
Acute Hypoxia ◽  
Peripheral Chemoreceptor

Chemoreceptor function was studied in eight 2- to 3-day-old unanesthetized lambs to sequentially assess hypoxic chemoreflex strength during an 18-min exposure to hypoxia [inspired O2 fraction (FIO2) = 0.08]. The immediate ventilatory (VE) drop in response to five breaths of pure O2 was measured at 3, 7, and 15 min during hypoxia. Each lamb was studied again at 10–11 days of age. At 2–3 days of age VE increased, with the onset of hypoxia, from 658 +/- 133 (SD) ml.min-1 X kg-1 to a peak of 1,124 +/- 177 ml.min-1 X kg-1. A dampening of the VE response then occurred, with a mean decline in VE of 319 ml.min-1 X kg-1 over the 18-min hypoxia period. Each pure O2 test (Dejours test) resulted in an abrupt fall in VE (delta VEDejours). This VE drop was 937 +/- 163, 868 +/- 244, and 707 +/- 120 ml.min-1 X kg-1 at 3, 7, and 15 min of hypoxia, respectively. Comparing the three O2 tests, delta VEDejours was significantly decreased by 15 min, indicating a loss of about one-fourth of the O2 chemoreflex drive during hypoxia. Testing at 10–11 days of age revealed a smaller VE decline during hypoxia. O2 tests at the beginning and end of the hypoxic period were not significantly different, indicating a smaller loss of hypoxic chemoreflex drive in the more mature animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Peripheral chemoreceptors in health and disease

2004 ◽  
Vol 96 (1) ◽  
pp. 359-366 ◽  
Author(s):  
Nanduri R. Prabhakar ◽  
Ying-Jie Peng
Keyword(s):  
Heart Failure ◽  
Congestive Heart Failure ◽  
Defense Mechanism ◽  
Experimental Models ◽  
Cellular Mechanisms ◽  
Peripheral Chemoreceptor ◽  
Peripheral Chemoreceptors ◽  
Oxygen Homeostasis ◽  
Arterial Blood ◽  
Carotid Bodies

Peripheral chemoreceptors (carotid and aortic bodies) detect changes in arterial blood oxygen and initiate reflexes that are important for maintaining homeostasis during hypoxemia. This mini-review summarizes the importance of peripheral chemoreceptor reflexes in various physiological and pathophysiological conditions. Carotid bodies are important for eliciting hypoxic ventilatory stimulation in humans and in experimental animals. In the absence of carotid bodies, compensatory upregulation of aortic bodies as well as other chemoreceptors contributes to the hypoxic ventilatory response. Peripheral chemoreceptors are critical for ventilatory acclimatization at high altitude. They also contribute in part to the exercise-induced hyperventilation, especially with submaximal and heavy exercise. During pregnancy, hypoxic ventilatory sensitivity increases, perhaps due to the actions of estrogen and progesterone on chemoreceptors. Augmented peripheral chemoreceptors have been implicated in early stages of recurrent apneas, congestive heart failure, and certain forms of hypertension. It is likely that chemoreceptors tend to maintain oxygen homeostasis and act as a defense mechanism to prevent the progression of the morbidity associated with these diseases. Experimental models of recurrent apneas, congestive heart failure, and hypertension offer excellent opportunities to unravel the cellular mechanisms associated with altered chemoreceptor function.

Effect of peripheral chemoreceptor denervation on acclimatization of goats during hypoxia

1981 ◽  
Vol 50 (2) ◽  
pp. 392-398 ◽  
Author(s):  
H. V. Forster ◽  
G. E. Bisgard ◽  
J. P. Klein
Keyword(s):  
Sea Level ◽  
Chronic Hypoxia ◽  
Alveolar Ventilation ◽  
Simulated Altitude ◽  
Peripheral Chemoreceptor ◽  
Peripheral Chemoreceptors ◽  
Carotid Chemoreceptors ◽  
Co2 Output

The purpose of this study was to determine the effect of peripheral chemoreceptor denervation on ventilatory acclimatization of goats during chronic hypoxia. After 1 h of stimulated altitude (PB 450 Torr), arterial O2 tension (PaO2) in seven normal goats averaged 42 Torr, and arterial CO2 tension (PaCO2) was 1.3 Torr below control (P less than 0.001). In these goats nearly 66% of the increase in alveolar ventilation (VA) associated with acclimatization occurred between 1.5 and 4 h of hypoxia. Acclimatization was complete by the 3rd day of hypoxia, and it caused 1) a 23% increase in VA/CO2 output (P less than 0.001); 2) a 5-Torr increase in PaO2 (P less than 0.001); and 3) a 6.5-Torr decrease in PaCO2 (P less than 0.001). Denervation of the carotid chemoreceptors in seven goats caused hypoventilation during eupnea at sea level (PaCO2 change from control +7 Torr, P less than 0.001). Denervation also attenuated but did not eliminate peripheral chemoreceptor responsiveness. No additional changes were observed following attempted denervation of the aortic chemoreceptors. After 1 h of simulated altitude (PB 530 Torr), PaO2 in the denervated goats averaged 46 Torr, and PaCO2 was increased 1.1 Torr above control (P less than 0.001). In these goats VA did not change significantly during the subsequent 3 days of hypoxia. Accordingly, we conclude that the peripheral chemoreceptors are essential for ventilatory acclimatization of goats during chronic hypoxia.

Predominant role of peripheral chemoreceptors in the termination of apnea in maturing newborn lambs

1996 ◽  
Vol 80 (3) ◽  
pp. 892-898 ◽  
Author(s):  
C. Delacourt ◽  
E. Canet ◽  
M. A. Bureau
Keyword(s):  
Carotid Body ◽  
Pco2 Level ◽  
Peripheral Chemoreceptor ◽  
Arterial Pco2 ◽  
Postnatal Maturation ◽  
Body Function ◽  
Life Threatening ◽  
Prolonged Apnea ◽  
Arterial Po2

Apneas are very common and normal in newborns but may become life threatening if they are not terminated appropriately. The aim of this study in newborn lambs was to investigate the influence on apnea termination of postnatal maturation, peripheral chemoreceptor function, and hypoxia. Apneas were induced by passive hyperventilation at varying inspired O2 fraction levels. The apnea termination threshold PCO2 (PATTCO2) was defined as the arterial PCO2 value at the first breath after the apnea. Three groups of awake intubated lambs were studied: 1) intact lambs tested at both 1 and 15 days of life, 2) intact 1-day-old lambs with central tissue hypoxia induced by CO inhalation, and 3) 1-day-old lambs with carotid body denervation (CBD). In individual lambs and regardless of age and carotid body function, there was a PO2-PCO2 response curve that was a determinant for the termination of an apnea. PATTCO2 invariably increased when arterial PO2 increased, regardless of age. During hypoxia and normoxia, PATTCO2 was significantly lower in 15-day-old lambs compared with 1-day-old lambs. No difference was seen during hyperoxia. PATTCO2 values were shifted to higher levels after carotid body removal. Finally, hypoxia induced by either a low inspired O2 fraction or CO inhalation consistently failed to induce a depressive effect on the PATTCO2 even in CBD lambs. In conclusion, in awake newborn lambs, the PCO2 level for apnea termination changed with postnatal age, and carotid body function was essential in lowering PATTCO2, thus protecting the lambs against prolonged apnea. Furthermore, hypoxia consistently failed to depress the reinitiation of breathing after apnea, even in CBD lambs.

Brain glutamate metabolism during hypoxia and peripheral chemodenervation

1990 ◽  
Vol 69 (1) ◽  
pp. 147-154 ◽  
Author(s):  
B. Hoop ◽  
M. R. Masjedi ◽  
V. E. Shih ◽  
H. Kazemi
Keyword(s):  
Brain Tissue ◽  
Gamma Aminobutyric Acid ◽  
Glutamate Metabolism ◽  
Peripheral Chemoreceptor ◽  
Transfer Rates ◽  
Neural Excitability ◽  
Glutamate Concentration ◽  
Ventilatory Drive ◽  
Anesthetized Dogs

Glutamate stimulates resting ventilation by altering neural excitability centrally. Hypoxia increases central ventilatory drive through peripheral chemoreceptor stimulation and may also alter cerebral perfusion and glutamate metabolism locally. Therefore the effect of hypoxia and peripheral chemodenervation on cerebrospinal fluid (CSF) transfer rate of in vivo tracer amidated central nervous system glutamate was studied in intact and chemodenervated pentobarbital-anesthetized dogs during normoxia and after 1 h of hypoxia induced with 10 or 12% O2 in N2 breathing at constant expired ventilation and arterial CO2 tension. Chemodenervation was performed by bilateral sectioning of the carotid body nerves and cervical vagi. CSF transfer rates of radiotracer 13NH4+ and [13N]glutamine synthesized via the reaction, glutamate + NH4(+)----glutamine, in brain glia were measured during normoxia and after 1 h of hypoxia. At normoxia, maximal glial glutamine efflux rate jm = 103.3 +/- 11.2 (SE) mumol.l-1.min-1 in all animals. After 1 h of hypoxia in intact animals, jm = 78.4 +/- 10.0 mumol.l-1.min-1. In denervated animals, jm was decreased to 46.3 +/- 4.3 mumol.l-1.min-1. During hypoxia, mean cerebral cortical glutamate concentration was higher in denervated animals (9.98 +/- 1.43 mumol/g brain tissue) than in intact animals (7.63 +/- 1.82 mumol/g brain tissue) and corresponding medullary glutamate concentration tended to be higher in denervated animals. There were no differences between mean glutamine and gamma-aminobutyric acid concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

Peripheral chemoreceptor function in children with the congenital central hypoventilation syndrome

1993 ◽  
Vol 74 (1) ◽  
pp. 379-387 ◽  
Author(s):  
D. Gozal ◽  
C. L. Marcus ◽  
D. Shoseyov ◽  
T. G. Keens
Keyword(s):  
Vital Capacity ◽  
Minute Ventilation ◽  
Acute Hypoxia ◽  
Clinical Manifestations ◽  
Congenital Central Hypoventilation Syndrome ◽  
Tidal Breathing ◽  
Peripheral Chemoreceptor ◽  
Ventilatory Responses ◽  
Central Hypoventilation ◽  
Hypoventilation Syndrome

In children with the congenital central hypoventilation syndrome (CCHS), some patients require mechanical ventilation during sleep, whereas others need respiratory assistance even when awake. The cause of this disparity is unclear. We hypothesized that differences in peripheral chemoreceptor response (PCR) could provide an explanatory mechanism for this disparity in clinical manifestations. PCR was measured in five children with CCHS and five sex- and age-matched controls by measuring the ventilatory responses induced by 100% O2 breathing, five tidal breaths of 100% N2, and vital capacity breaths of 5% and 15% CO2 in O2 and 5% CO2–95% N2. Tidal breathing of 100% O2 resulted in similar ventilatory responses in CCHS patients and controls with various changes dependent on the method of analysis of response used. Acute hypoxia by N2 tidal breathing resulted in a 39.2 +/- 22% increase in respiratory rate in CCHS patients and a 15.1 +/- 11.1% increase in controls (P < 0.05), with similar increases in minute ventilation (VE) of 124 +/- 69% and 85 +/- 11%, respectively. Vital capacity breaths of each of the CO2-containing gas mixtures induced similar increases in VE in CCHS patients and controls. The changes in VE obtained with 15% CO2–85% O2 and with 5% CO2–95% N2 were significantly greater than those with 5% CO2–95% O2, suggesting a dose-dependent response as well as additive effects of hypercapnic and hypoxic stimuli. We conclude that the PCR, when assessed by acute hypoxia, hyperoxia, or hypercapnia, is present and intact in CCHS children who are able to sustain adequate ventilation during wakefulness.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals CBmeter study: protocol for assessing the predictive value of peripheral chemoreceptor overactivation for metabolic diseases

BMJ Open ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. e042825
Author(s):  
Marlene Lages ◽  
Lucinda Carvalho ◽  
Salvato Feijó ◽  
Alexandra Vieira ◽  
Rui Fonseca-Pinto ◽  
...  
Keyword(s):  
Predictive Value ◽  
Metabolic Diseases ◽  
Primary Objective ◽  
Metabolic Responses ◽  
Diabetes Diagnosis ◽  
Metabolic Disturbances ◽  
Early Screening ◽  
Peripheral Chemoreceptor ◽  
New Therapeutic Approaches ◽  
Oxygen Administration

IntroductionEarly screening of metabolic diseases is crucial since continued undiagnostic places an ever-increasing burden on healthcare systems. Recent studies suggest a link between overactivated carotid bodies (CB) and the genesis of type 2 diabetes mellitus. The non-invasive assessment of CB activity by measuring ventilatory, cardiac and metabolic responses to challenge tests may have predictive value for metabolic diseases; however, there are no commercially available devices that assess CB activity. The findings of the CBmeter study will clarify the role of the CBs in the genesis of—metabolic diseases and guide the development of new therapeutic approaches for early intervention in metabolic disturbances. Results may also contribute to patient classification and stratification for future CB modulatory interventions.MethodsThis is a non-randomised, multicentric, controlled clinical study. Forty participants (20 control and 20 diabetics) will be recruited from secondary and primary healthcare settings. The primary objective is to establish a new model of early diagnosis of metabolic diseases based on the respiratory and metabolic responses to transient 100% oxygen administration and ingestion of a standardised mixed meal.AnalysisRaw data acquired with the CBmeter will be endorsed against gold standard techniques for heart rate, respiratory rate, oxygen saturation and interstitial glucose quantification and analysed a multivariate analysis software developed specifically for the CBmeter study (CBview). Data will be analysed using clustering analysis and artificial intelligence methods based on unsupervised learning algorithms, to establish the predictive value of diabetes diagnosis.EthicsThe study was approved by the Ethics Committee of the Leiria Hospital Centre. Patients will be asked for written informed consent and data will be coded to ensure the anonymity of data.DisseminationResults will be disseminated through publication in peer-reviewed journals and relevant medical and health conferences.

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