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Conde SV, Martins FO, Sacramento JF. Carotid body interoception in health and disease. Auton Neurosci 2024; 255:103207. [PMID: 39121687 DOI: 10.1016/j.autneu.2024.103207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2024] [Revised: 07/15/2024] [Accepted: 07/26/2024] [Indexed: 08/12/2024]
Abstract
Interoception entails perceiving or being aware of the internal state of the body, playing a pivotal role in regulating processes such as heartbeat, digestion, glucose metabolism, and respiration. The carotid body (CB) serves as an interoceptive organ, transmitting information to the brain via its sensitive nerve, the carotid sinus nerve, to maintain homeostasis. While traditionally known for sensing oxygen, carbon dioxide, and pH levels, the CB is now recognized to possess additional interoceptive properties, detecting various mediators involved in blood pressure regulation, inflammation, and glucose homeostasis, among other physiological functions. Furthermore, in the last decades CB dysfunction has been linked to diseases like sleep apnea, essential hypertension, and diabetes. In this review manuscript, we make a concise overview of the traditional interoceptive functions of the CB, acting as a sensor for oxygen levels, carbon dioxide levels, and pH, and introduce the novel interoceptive properties of the CB related to vascular, glucose and energy regulation. Additionally, we revise the contribution of the CB to the onset and progression of metabolic diseases, delving into the potential dysfunction of its interoceptive metabolic functions as a contributing factor to pathophysiology. Finally, we postulate the use of therapeutic interventions targeting the metabolic interoceptive properties of the CB as a potential avenue for addressing metabolic diseases.
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Affiliation(s)
- Silvia V Conde
- iNOVA4Health, NOVA Medical School, Faculdade de Ciências Médicas, Universidade Nova de Lisboa, Lisboa, Portugal.
| | - Fatima O Martins
- iNOVA4Health, NOVA Medical School, Faculdade de Ciências Médicas, Universidade Nova de Lisboa, Lisboa, Portugal
| | - Joana F Sacramento
- iNOVA4Health, NOVA Medical School, Faculdade de Ciências Médicas, Universidade Nova de Lisboa, Lisboa, Portugal
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Thakkar P, Pauza AG, Murphy D, Paton JFR. Carotid body: an emerging target for cardiometabolic co-morbidities. Exp Physiol 2023; 108:661-671. [PMID: 36999224 PMCID: PMC10988524 DOI: 10.1113/ep090090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Accepted: 03/03/2023] [Indexed: 04/01/2023]
Abstract
NEW FINDINGS What is the topic of this review? Regarding the global metabolic syndrome crisis, this review focuses on common mechanisms for high blood sugar and high blood pressure. Connections are made between the homeostatic regulation of blood pressure and blood sugar and their dysregulation to reveal signalling mechanisms converging on the carotid body. What advances does it highlight? The carotid body plays a major part in the generation of excessive sympathetic activity in diabetes and also underpins diabetic hypertension. As treatment of diabetic hypertension is notoriously difficult, we propose that novel receptors within the carotid body may provide a novel treatment strategy. ABSTRACT The maintenance of glucose homeostasis is obligatory for health and survival. It relies on peripheral glucose sensing and signalling between the brain and peripheral organs via hormonal and neural responses that restore euglycaemia. Failure of these mechanisms causes hyperglycaemia or diabetes. Current anti-diabetic medications control blood glucose but many patients remain with hyperglycemic condition. Diabetes is often associated with hypertension; the latter is more difficult to control in hyperglycaemic conditions. We ask whether a better understanding of the regulatory mechanisms of glucose control could improve treatment of both diabetes and hypertension when they co-exist. With the involvement of the carotid body (CB) in glucose sensing, metabolic regulation and control of sympathetic nerve activity, we consider the CB as a potential treatment target for both diabetes and hypertension. We provide an update on the role of the CB in glucose sensing and glucose homeostasis. Physiologically, hypoglycaemia stimulates the release of hormones such as glucagon and adrenaline, which mobilize or synthesize glucose; however, these counter-regulatory responses were markedly attenuated after denervation of the CBs in animals. Also, CB denervation prevents and reverses insulin resistance and glucose intolerance. We discuss the CB as a metabolic regulator (not just a sensor of blood gases) and consider recent evidence of novel 'metabolic' receptors within the CB and putative signalling peptides that may control glucose homeostasis via modulation of the sympathetic nervous system. The evidence presented may inform future clinical strategies in the treatment of patients with both diabetes and hypertension, which may include the CB.
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Affiliation(s)
- Pratik Thakkar
- Manaaki Manawa – the Centre for Heart Research, Department of Physiology, Faculty of Medical and Health SciencesUniversity of AucklandAucklandNew Zealand
| | - Audrys G. Pauza
- Manaaki Manawa – the Centre for Heart Research, Department of Physiology, Faculty of Medical and Health SciencesUniversity of AucklandAucklandNew Zealand
| | - David Murphy
- Molecular Neuroendocrinology Research Group, Bristol Medical School: Translational Health SciencesUniversity of BristolBristolUK
| | - Julian F. R. Paton
- Manaaki Manawa – the Centre for Heart Research, Department of Physiology, Faculty of Medical and Health SciencesUniversity of AucklandAucklandNew Zealand
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Baby SM, Zaidi F, Hunsberger GE, Sokal D, Gupta I, Conde SV, Chew D, Rall K, Coatney RW. Acute effects of insulin and insulin-induced hypoglycaemia on carotid body chemoreceptor activity and cardiorespiratory responses in dogs. Exp Physiol 2023; 108:280-295. [PMID: 36459572 PMCID: PMC10103873 DOI: 10.1113/ep090584] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 11/07/2022] [Indexed: 12/03/2022]
Abstract
NEW FINDINGS What is the central question of this study? What are the effects of insulin and insulin-induced hypoglycaemia on carotid body chemoreceptor activity in vivo and how do carotid body chemoreceptor stimulation-mediated cardiorespiratory responses in beagle dogs compare during euglycaemia and insulin-induced hypoglycaemia? What is the main finding and its importance? Intracarotid insulin administration leads to sustained increase in carotid body chemoreceptor activity and respiratory response with significant cardiovascular effects. Insulin-induced hypoglycaemia exacerbated NaCN-mediated carotid body chemoreceptor activity and respiratory response with enhanced cardiovascular reflex response. These findings suggest that insulin-induced hypoglycaemia augments the carotid body chemoreceptors to initiate the adaptive counter-regulatory responses to restore the normoglycaemic condition. ABSTRACT The carotid body chemoreceptors (CBC) play an important role in the adaptive counter-regulatory response to hypoglycaemia by evoking the CBC-mediated sympathetic neuronal system to restore normoglycaemia. Ex vivo studies have shown varied responses of insulin-induced hypoglycaemia on CBC function, and several in vivo studies have indirectly established the role of CBCs in restoring normoglycaemia in both animals and humans. However, a direct effect of insulin and/or insulin-induced hypoglycaemia on CBC activity is not established in animal models. Therefore, the aim of this study was to evaluate in vivo effects of insulin and insulin-induced hypoglycaemia on CBC activity and cardiorespiration in a preclinical large animal model. The carotid sinus nerve (CSN) activity and cardiorespiratory responses to sodium cyanide (NaCN; 25 µg/kg) were compared before (euglycaemic) and after (hypoglycaemic) intracarotid administration of insulin (12.5-100 µU/dogs) in beagle dogs. Insulin administration increased CSN activity and minute ventilation (V ̇ $\dot V$ E ) with significant (P < 0.0001) effects on heart rate and blood pressure. Insulin-mediated effects on CSN and cardiorespiration were sustained and the change inV ̇ $\dot V$ E was driven by tidal volume only. Insulin significantly (P < 0.0001) lowered blood glucose level. NaCN-mediated CSN activity andV ̇ $\dot V$ E were significantly (P < 0.0001) augmented during insulin-induced hypoglycaemia. The augmentedV ̇ $\dot V$ E was primarily driven by respiratory frequency and partially by tidal volume. The cardiovascular reflex response mediated through CBC stimulation was significantly (P < 0.0001) exacerbated during insulin-induced hypoglycaemia. Collectively, these results demonstrate direct effects of insulin and insulin-induced hypoglycaemia on CBC chemosensitivity to potentiate CBC-mediated neuroregulatory pathways to initiate adaptive neuroendocrine and cardiorespiratory counter-regulatory responses to restore normoglycaemia.
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Affiliation(s)
- Santhosh M. Baby
- Translational Sciences and Treatment DiscoveryGalvani BioelectronicsCollegevillePAUSA
| | - Faisal Zaidi
- Translational Sciences and Treatment DiscoveryGalvani BioelectronicsCollegevillePAUSA
| | | | - David Sokal
- Experimental MedicineSurgical Development and TherapyGalvani BioelectronicsStevenageUK
| | - Isha Gupta
- Experimental MedicineSurgical Development and TherapyGalvani BioelectronicsStevenageUK
| | - Silvia V. Conde
- NOVA Medical SchoolFaculdade de Ciências MédicasUniversidade Nova de LisboaLisboaPortugal
| | - Daniel Chew
- Experimental MedicineSurgical Development and TherapyGalvani BioelectronicsStevenageUK
| | - Kristen Rall
- Translational Sciences and Treatment DiscoveryGalvani BioelectronicsCollegevillePAUSA
| | - Robert W. Coatney
- Translational Sciences and Treatment DiscoveryGalvani BioelectronicsCollegevillePAUSA
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Dai L, Wang X, Xiao Y. Role of chemosensitivity: Possible pathophysiological mediator of obstructive sleep apnea and type 2 diabetes. Sleep Med 2023; 101:490-496. [PMID: 36527940 DOI: 10.1016/j.sleep.2022.12.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2022] [Accepted: 12/05/2022] [Indexed: 12/12/2022]
Abstract
Obstructive sleep apnea (OSA) and type 2 diabetes show some mutual promotion of disease development. Variation in chemosensitivity is a key contributor to the pathophysiological mechanisms causing OSA and type 2 diabetes. According to studies conducted thus far, people with OSA or type 2 diabetes may have higher chemoreflex levels, but it is challenging to identify the precise changes because of variations in participant characteristics, the severity of the disease at the time of recruitment, and the small sample sizes in each study. Lowering chemosensitivity may also be viewed as a new issue for individuals with OSA and type 2 diabetes who require personalized care. The purpose of this review was to give an overview of chemosensitivity changes in OSA and glucose metabolism, as well as prospective therapeutic treatments for patients with OSA and type 2 diabetes.
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Affiliation(s)
- Lu Dai
- Department of Respiratory and Critical Care Medicine, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, 100730, China
| | - Xiaona Wang
- Department of Respiratory and Critical Care Medicine, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, 100730, China
| | - Yi Xiao
- Department of Respiratory and Critical Care Medicine, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, 100730, China.
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Kulej-Lyko K, Niewinski P, Tubek S, Krawczyk M, Kosmala W, Ponikowski P. Inhibition of peripheral chemoreceptors improves ventilatory efficiency during exercise in heart failure with preserved ejection fraction − a role of tonic activity and acute reflex response. Front Physiol 2022; 13:911636. [PMID: 36111161 PMCID: PMC9470150 DOI: 10.3389/fphys.2022.911636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2022] [Accepted: 07/19/2022] [Indexed: 11/22/2022] Open
Abstract
Peripheral chemoreceptors (PChRs) play a significant role in maintaining adequate oxygenation in the bloodstream. PChRs functionality comprises two components: tonic activity (PChT) which regulates ventilation during normoxia and acute reflex response (peripheral chemosensitivity, PChS), which increases ventilation following a specific stimulus. There is a clear link between augmented PChS and exercise intolerance in patients with heart failure with reduced ejection fraction. It has been also shown that inhibition of PChRs leads to the improvement in exercise capacity. However, it has not been established yet: 1) whether similar mechanisms take part in heart failure with preserved ejection fraction (HFpEF) and 2) which component of PChRs functionality (PChT vs. PChS) is responsible for the benefit seen after the acute experimental blockade. To answer those questions we enrolled 12 stable patients with HFpEF. All participants underwent an assessment of PChT (attenuation of minute ventilation in response to low-dose dopamine infusion), PChS (enhancement of minute ventilation in response to hypoxia) and a symptom-limited cardiopulmonary exercise test on cycle ergometer. All tests were placebo-controlled, double-blinded and performed in a randomized order. Under resting conditions and at normoxia dopamine attenuated minute ventilation and systemic vascular resistance (p = 0.03 for both). These changes were not seen with placebo. Dopamine also decreased ventilatory and mean arterial pressure responses to hypoxia (p < 0.05 for both). Inhibition of PChRs led to a decrease in V˙E/V˙CO2 comparing to placebo (36 ± 3.6 vs. 34.3 ± 3.7, p = 0.04), with no effect on peak oxygen consumption. We found a significant relationship between PChT and the relative decrement of V˙E/V˙CO2 on dopamine comparing to placebo (R = 0.76, p = 0.005). There was a trend for correlation between PChS (on placebo) and V˙E/V˙CO2 during placebo infusion (R = 0.56, p = 0.059), but the relative improvement in V˙E/V˙CO2 was not related to the change in PChS (dopamine vs. placebo). We did not find a significant relationship between PChT and PChS. In conclusion, inhibition of PChRs in HFpEF population improves ventilatory efficiency during exercise. Increased PChS is associated with worse (higher) V˙E/V˙CO2, whereas PChT predicts an improvement in V˙E/V˙CO2 after PChRs inhibition. This results may be meaningful for patient selection in further clinical trials involving PChRs modulation.
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Affiliation(s)
- Katarzyna Kulej-Lyko
- Institute of Heart Diseases, Wroclaw Medical University, Wroclaw, Poland
- Department of Cardiology, University Clinical Hospital, Wroclaw, Poland
- *Correspondence: Katarzyna Kulej-Lyko,
| | - Piotr Niewinski
- Institute of Heart Diseases, Wroclaw Medical University, Wroclaw, Poland
- Department of Cardiology, University Clinical Hospital, Wroclaw, Poland
| | - Stanislaw Tubek
- Institute of Heart Diseases, Wroclaw Medical University, Wroclaw, Poland
- Department of Cardiology, University Clinical Hospital, Wroclaw, Poland
| | | | - Wojciech Kosmala
- Institute of Heart Diseases, Wroclaw Medical University, Wroclaw, Poland
- Department of Cardiology, University Clinical Hospital, Wroclaw, Poland
| | - Piotr Ponikowski
- Institute of Heart Diseases, Wroclaw Medical University, Wroclaw, Poland
- Department of Cardiology, University Clinical Hospital, Wroclaw, Poland
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Melo BF, Sacramento JF, Capucho AM, Sampaio-Pires D, Prego CS, Conde SV. Long-Term Hypercaloric Diet Consumption Exacerbates Age-Induced Dysmetabolism and Carotid Body Dysfunction: Beneficial Effects of CSN Denervation. Front Physiol 2022; 13:889660. [PMID: 35600301 PMCID: PMC9114486 DOI: 10.3389/fphys.2022.889660] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Accepted: 04/06/2022] [Indexed: 12/22/2022] Open
Abstract
Carotid bodies (CBs) are metabolic sensors whose dysfunction is involved in the genesis of dysmetabolic states. Ageing induces significant alterations in CB function also prompting to metabolic deregulation. On the other hand, metabolic disease can accelerate ageing processes. Taking these into account, we evaluated the effect of long-term hypercaloric diet intake and CSN resection on age-induced dysmetabolism and CB function. Experiments were performed in male Wistar rats subjected to 14 or 44 weeks of high-fat high-sucrose (HFHSu) or normal chow (NC) diet and subjected to either carotid sinus nerve (CSN) resection or a sham procedure. After surgery, the animals were kept on a diet for more than 9 weeks. Metabolic parameters, basal ventilation, and hypoxic and hypercapnic ventilatory responses were evaluated. CB type I and type II cells, HIF-1α and insulin receptor (IR), and GLP-1 receptor (GLP1-R)-positive staining were analyzed by immunofluorescence. Ageing decreased by 61% insulin sensitivity in NC animals, without altering glucose tolerance. Short-term and long-term HFHSu intake decreased insulin sensitivity by 55 and 62% and glucose tolerance by 8 and 29%, respectively. CSN resection restored insulin sensitivity and glucose tolerance. Ageing decreased spontaneous ventilation, but short-term or long-term intake of HFHSu diet and CSN resection did not modify basal ventilatory parameters. HFHSu diet increased hypoxic ventilatory responses in young and adult animals, effects attenuated by CSN resection. Ageing, hypercaloric diet, and CSN resection did not change hypercapnic ventilatory responses. Adult animals showed decreased type I cells and IR and GLP-1R staining without altering the number of type II cells and HIF-1α. HFHSu diet increased the number of type I and II cells and IR in young animals without significantly changing these values in adult animals. CSN resection restored the number of type I cells in HFHSu animals and decreased IR-positive staining in all the groups of animals, without altering type II cells, HIF-1α, or GLP-1R staining. In conclusion, long-term hypercaloric diet consumption exacerbates age-induced dysmetabolism, and both short- and long-term hypercaloric diet intakes promote significant alterations in CB function. CSN resection ameliorates these effects. We suggest that modulation of CB activity is beneficial in exacerbated stages of dysmetabolism.
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Pauza AG, Thakkar P, Tasic T, Felippe I, Bishop P, Greenwood MP, Rysevaite-Kyguoliene K, Ast J, Broichhagen J, Hodson DJ, Salgado HC, Pauza DH, Japundzic-Zigon N, Paton JFR, Murphy D. GLP1R Attenuates Sympathetic Response to High Glucose via Carotid Body Inhibition. Circ Res 2022; 130:694-707. [PMID: 35100822 PMCID: PMC8893134 DOI: 10.1161/circresaha.121.319874] [Citation(s) in RCA: 33] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Supplemental Digital Content is available in the text. Aberrant sympathetic nerve activity exacerbates cardiovascular risk in hypertension and diabetes, which are common comorbidities, yet clinically sympathetic nerve activity remains poorly controlled. The hypertensive diabetic state is associated with increased reflex sensitivity and tonic drive from the peripheral chemoreceptors, the cause of which is unknown. We have previously shown hypertension to be critically dependent on the carotid body (CB) input in spontaneously hypertensive rat, a model that also exhibits a number of diabetic traits. CB overstimulation by insulin and leptin has been similarly implicated in the development of increased sympathetic nerve activity in metabolic syndrome and obesity. Thus, we hypothesized that in hypertensive diabetic state (spontaneously hypertensive rat), the CB is sensitized by altered metabolic signaling causing excessive sympathetic activity levels and dysfunctional reflex regulation.
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Affiliation(s)
- Audrys G Pauza
- Bristol Medical School, Translational Health Sciences, University of Bristol, United Kingdom (A.G.P., P.B., M.P.G., D.M.)
| | - Pratik Thakkar
- Manaaki Mānawa - The Centre for Heart Research, Department of Physiology, Faculty of Medical & Health Sciences, University of Auckland, New Zealand (P.T., I.F., J.F.R.P.)
| | - Tatjana Tasic
- School of Dental Medicine, University of Belgrade, Serbia (T.T.)
| | - Igor Felippe
- Manaaki Mānawa - The Centre for Heart Research, Department of Physiology, Faculty of Medical & Health Sciences, University of Auckland, New Zealand (P.T., I.F., J.F.R.P.)
| | - Paul Bishop
- Bristol Medical School, Translational Health Sciences, University of Bristol, United Kingdom (A.G.P., P.B., M.P.G., D.M.)
| | - Michael P Greenwood
- Bristol Medical School, Translational Health Sciences, University of Bristol, United Kingdom (A.G.P., P.B., M.P.G., D.M.)
| | | | - Julia Ast
- Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, United Kingdom (J.A., D.J.H.)
| | | | - David J Hodson
- Institute of Metabolism and Systems Research (IMSR), and Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham, United Kingdom (D.A., D.J.H.).,Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, United Kingdom (J.A., D.J.H.)
| | - Helio C Salgado
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Brazil (H.C.S.)
| | - Dainius H Pauza
- Institute of Anatomy, Faculty of Medicine, Lithuanian University of Health Sciences, Kaunas (K.R.-K., D.H.P.)
| | - Nina Japundzic-Zigon
- Institute of Pharmacology, Clinical Pharmacology and Toxicology, Faculty of Medicine, University of Belgrade, Serbia (N.J.-Z.)
| | - Julian F R Paton
- Manaaki Mānawa - The Centre for Heart Research, Department of Physiology, Faculty of Medical & Health Sciences, University of Auckland, New Zealand (P.T., I.F., J.F.R.P.)
| | - David Murphy
- Bristol Medical School, Translational Health Sciences, University of Bristol, United Kingdom (A.G.P., P.B., M.P.G., D.M.)
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Abstract
The carotid body (CB) is a bilateral arterial chemoreceptor located in the carotid artery bifurcation with an essential role in cardiorespiratory homeostasis. It is composed of highly perfused cell clusters, or glomeruli, innervated by sensory fibers. Glomus cells, the most abundant in each glomerulus, are neuron-like multimodal sensory elements able to detect and integrate changes in several physical and chemical parameters of the blood, in particular O2 tension, CO2 and pH, as well as glucose, lactate, or blood flow. Activation of glomus cells (e.g., during hypoxia or hypercapnia) stimulates the afferent fibers which impinge on brainstem neurons to elicit rapid compensatory responses (hyperventilation and sympathetic activation). This chapter presents an updated view of the structural organization of the CB and the mechanisms underlying the chemosensory responses of glomus cells, with special emphasis on the molecular processes responsible for acute O2 sensing. The properties of the glomus cell-sensory fiber synapse as well as the organization of CB output are discussed. The chapter includes the description of recently discovered CB stem cells and progenitor cells, and their role in CB growth during acclimatization to hypoxemia. Finally, the participation of the CB in the mechanisms of disease is briefly discussed.
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Affiliation(s)
- José López-Barneo
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/Consejo Superior de Investigaciones Científicas (CSIC)/Universidad de Sevilla, Seville, Spain; Biomedical Research Center for Neurodegenerative Diseases (CIBERNED), Madrid, Spain.
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Proczka M, Przybylski J, Cudnoch-Jędrzejewska A, Szczepańska-Sadowska E, Żera T. Vasopressin and Breathing: Review of Evidence for Respiratory Effects of the Antidiuretic Hormone. Front Physiol 2021; 12:744177. [PMID: 34867449 PMCID: PMC8637824 DOI: 10.3389/fphys.2021.744177] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Accepted: 09/27/2021] [Indexed: 12/17/2022] Open
Abstract
Vasopressin (AVP) is a key neurohormone involved in the regulation of body functions. Due to its urine-concentrating effect in the kidneys, it is often referred to as antidiuretic hormone. Besides its antidiuretic renal effects, AVP is a potent neurohormone involved in the regulation of arterial blood pressure, sympathetic activity, baroreflex sensitivity, glucose homeostasis, release of glucocorticoids and catecholamines, stress response, anxiety, memory, and behavior. Vasopressin is synthesized in the paraventricular (PVN) and supraoptic nuclei (SON) of the hypothalamus and released into the circulation from the posterior lobe of the pituitary gland together with a C-terminal fragment of pro-vasopressin, known as copeptin. Additionally, vasopressinergic neurons project from the hypothalamus to the brainstem nuclei. Increased release of AVP into the circulation and elevated levels of its surrogate marker copeptin are found in pulmonary diseases, arterial hypertension, heart failure, obstructive sleep apnoea, severe infections, COVID-19 due to SARS-CoV-2 infection, and brain injuries. All these conditions are usually accompanied by respiratory disturbances. The main stimuli that trigger AVP release include hyperosmolality, hypovolemia, hypotension, hypoxia, hypoglycemia, strenuous exercise, and angiotensin II (Ang II) and the same stimuli are known to affect pulmonary ventilation. In this light, we hypothesize that increased AVP release and changes in ventilation are not coincidental, but that the neurohormone contributes to the regulation of the respiratory system by fine-tuning of breathing in order to restore homeostasis. We discuss evidence in support of this presumption. Specifically, vasopressinergic neurons innervate the brainstem nuclei involved in the control of respiration. Moreover, vasopressin V1a receptors (V1aRs) are expressed on neurons in the respiratory centers of the brainstem, in the circumventricular organs (CVOs) that lack a blood-brain barrier, and on the chemosensitive type I cells in the carotid bodies. Finally, peripheral and central administrations of AVP or antagonists of V1aRs increase/decrease phrenic nerve activity and pulmonary ventilation in a site-specific manner. Altogether, the findings discussed in this review strongly argue for the hypothesis that vasopressin affects ventilation both as a blood-borne neurohormone and as a neurotransmitter within the central nervous system.
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Affiliation(s)
- Michał Proczka
- Department of Experimental and Clinical Physiology, Doctoral School, Medical University of Warsaw, Warsaw, Poland
| | - Jacek Przybylski
- Department of Biophysics, Physiology, and Pathophysiology, Laboratory of Centre for Preclinical Research, Medical University of Warsaw, Warsaw, Poland
| | - Agnieszka Cudnoch-Jędrzejewska
- Department of Experimental and Clinical Physiology, Laboratory of Centre for Preclinical Research, Medical University of Warsaw, Warsaw, Poland
| | - Ewa Szczepańska-Sadowska
- Department of Experimental and Clinical Physiology, Laboratory of Centre for Preclinical Research, Medical University of Warsaw, Warsaw, Poland
| | - Tymoteusz Żera
- Department of Experimental and Clinical Physiology, Laboratory of Centre for Preclinical Research, Medical University of Warsaw, Warsaw, Poland
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Iturriaga R, Alcayaga J, Chapleau MW, Somers VK. Carotid body chemoreceptors: physiology, pathology, and implications for health and disease. Physiol Rev 2021; 101:1177-1235. [PMID: 33570461 PMCID: PMC8526340 DOI: 10.1152/physrev.00039.2019] [Citation(s) in RCA: 81] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The carotid body (CB) is the main peripheral chemoreceptor for arterial respiratory gases O2 and CO2 and pH, eliciting reflex ventilatory, cardiovascular, and humoral responses to maintain homeostasis. This review examines the fundamental biology underlying CB chemoreceptor function, its contribution to integrated physiological responses, and its role in maintaining health and potentiating disease. Emphasis is placed on 1) transduction mechanisms in chemoreceptor (type I) cells, highlighting the role played by the hypoxic inhibition of O2-dependent K+ channels and mitochondrial oxidative metabolism, and their modification by intracellular molecules and other ion channels; 2) synaptic mechanisms linking type I cells and petrosal nerve terminals, focusing on the role played by the main proposed transmitters and modulatory gases, and the participation of glial cells in regulation of the chemosensory process; 3) integrated reflex responses to CB activation, emphasizing that the responses differ dramatically depending on the nature of the physiological, pathological, or environmental challenges, and the interactions of the chemoreceptor reflex with other reflexes in optimizing oxygen delivery to the tissues; and 4) the contribution of enhanced CB chemosensory discharge to autonomic and cardiorespiratory pathophysiology in obstructive sleep apnea, congestive heart failure, resistant hypertension, and metabolic diseases and how modulation of enhanced CB reactivity in disease conditions may attenuate pathophysiology.
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Affiliation(s)
- Rodrigo Iturriaga
- Laboratorio de Neurobiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile, and Centro de Excelencia en Biomedicina de Magallanes, Universidad de Magallanes, Punta Arenas, Chile
| | - Julio Alcayaga
- Laboratorio de Fisiología Celular, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Mark W Chapleau
- Department of Internal Medicine, University of Iowa and Department of Veterans Affairs Medical Center, Iowa City, Iowa
| | - Virend K Somers
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota
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11
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Conde SV, Sacramento JF, Martins FO. Immunity and the carotid body: implications for metabolic diseases. Bioelectron Med 2020; 6:24. [PMID: 33353562 PMCID: PMC7756955 DOI: 10.1186/s42234-020-00061-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Accepted: 11/24/2020] [Indexed: 12/14/2022] Open
Abstract
Neuro-immune communication has gained enormous interest in recent years due to increasing knowledge of the way in which the brain coordinates functional alterations in inflammatory and autoimmune responses, and the mechanisms of neuron-immune cell interactions in the context of metabolic diseases such as obesity and type 2 diabetes. In this review, we will explain how this relationship between the nervous and immune system impacts the pro- and anti-inflammatory pathways with specific reference to the hypothalamus-pituitary-adrenal gland axis and the vagal reflex and will explore the possible involvement of the carotid body (CB) in the neural control of inflammation. We will also highlight the mechanisms of vagal anti-inflammatory reflex control of immunity and metabolism, and the consequences of functional disarrangement of this reflex in settlement and development of metabolic diseases, with special attention to obesity and type 2 diabetes. Additionally, the role of CB in the interplay between metabolism and immune responses will be discussed, with specific reference to the different stimuli that promote CB activation and the balance between sympathetic and parasympathetic in this context. In doing so, we clarify the multivarious neuronal reflexes that coordinate tissue-specific responses (gut, pancreas, adipose tissue and liver) critical to metabolic control, and metabolic disease settlement and development. In the final section, we will summarize how electrical modulation of the carotid sinus nerve may be utilized to adjust these reflex responses and thus control inflammation and metabolic diseases, envisioning new therapeutics horizons.
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Affiliation(s)
- Silvia V Conde
- iNOVA4Health, CEDOC, NOVA Medical School, NMS, Universidade Nova de Lisboa, Rua Câmara Pestana, n°6, Edifício 2, piso 3, 1150-274, Lisbon, Portugal.
| | - Joana F Sacramento
- iNOVA4Health, CEDOC, NOVA Medical School, NMS, Universidade Nova de Lisboa, Rua Câmara Pestana, n°6, Edifício 2, piso 3, 1150-274, Lisbon, Portugal
| | - Fatima O Martins
- iNOVA4Health, CEDOC, NOVA Medical School, NMS, Universidade Nova de Lisboa, Rua Câmara Pestana, n°6, Edifício 2, piso 3, 1150-274, Lisbon, Portugal
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12
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Jana BA, Shinde U, Wadhwani A. Synthetic enzyme-based nanoparticles act as smart catalyst for glucose responsive release of insulin. J Biotechnol 2020; 324:1-6. [PMID: 32987063 DOI: 10.1016/j.jbiotec.2020.09.023] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 09/22/2020] [Accepted: 09/23/2020] [Indexed: 12/18/2022]
Abstract
BACKGROUND Earlier studies have attempted to create electronic free insulin delivery systems using different glucose sensing mechanism, no successful clinical translation as hitherto been made. This study aimed to assess the faster responsiveness of the insulin release from this enzyme based nanoparticles which is a self-regulated insulin delivery system constructed by loading with insulin, enzyme glucose oxidase into hyaluronic acid and 2-nitroimidazole forming enzyme-based nanoparticles which works in accordance to the blood glucose level. MATERIALS AND METHOD Enzyme-based nanoparticles were prepared by ionic gelation method. Insulin content in the nanoparticles kept for stability study was estimated by human insulin enzyme based immunosorbent assay. In in-vitro studies; different concentrations of glucose were taken and the release study of insulin was recorded. RESULTS This enzyme-based nanoparticles were having average diameter of around 193 nm and stability studies showed that nanoparticles were stable upto 30 days at 4 °C. In-vitro studies showed the release of insulin from nanoparticle conjugates which was effectively correlated with the external glucose concentration created where different concentrations of glucose taken thus facilitating the stabilization of blood glucose levels in the hyperglycemia state which was achieved within 10 min. (400 mg/dL) wherein drug release rate remarkably increased in hyperglycemia state and no specific changes or small amount of release was observed in normoglycemia state (100 mg/dL). CONCLUSION Overall, this preliminary study of this enzyme-based nanoparticles formulation showed excellent rapid responsiveness towards hyperglycemia which might act as a potential biomimetic system in triggering the release of insulin in sustained manner.
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Affiliation(s)
- Baishali A Jana
- Department of Pharmaceutical Biotechnology, JSS Academy of Higher Education & Research - JSS College of Pharmacy, Ooty, 643001, Tamil Nadu, India.
| | - Ujwala Shinde
- Department of Pharmaceutics, Bombay College of Pharmacy, Mumbai, 400098, Maharashtra, India.
| | - Ashish Wadhwani
- Department of Pharmaceutical Biotechnology, JSS Academy of Higher Education & Research - JSS College of Pharmacy, Ooty, 643001, Tamil Nadu, India.
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13
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Aldossary HS, Alzahrani AA, Nathanael D, Alhuthail EA, Ray CJ, Batis N, Kumar P, Coney AM, Holmes AP. G-Protein-Coupled Receptor (GPCR) Signaling in the Carotid Body: Roles in Hypoxia and Cardiovascular and Respiratory Disease. Int J Mol Sci 2020; 21:ijms21176012. [PMID: 32825527 PMCID: PMC7503665 DOI: 10.3390/ijms21176012] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 08/13/2020] [Accepted: 08/16/2020] [Indexed: 12/17/2022] Open
Abstract
The carotid body (CB) is an important organ located at the carotid bifurcation that constantly monitors the blood supplying the brain. During hypoxia, the CB immediately triggers an alarm in the form of nerve impulses sent to the brain. This activates protective reflexes including hyperventilation, tachycardia and vasoconstriction, to ensure blood and oxygen delivery to the brain and vital organs. However, in certain conditions, including obstructive sleep apnea, heart failure and essential/spontaneous hypertension, the CB becomes hyperactive, promoting neurogenic hypertension and arrhythmia. G-protein-coupled receptors (GPCRs) are very highly expressed in the CB and have key roles in mediating baseline CB activity and hypoxic sensitivity. Here, we provide a brief overview of the numerous GPCRs that are expressed in the CB, their mechanism of action and downstream effects. Furthermore, we will address how these GPCRs and signaling pathways may contribute to CB hyperactivity and cardiovascular and respiratory disease. GPCRs are a major target for drug discovery development. This information highlights specific GPCRs that could be targeted by novel or existing drugs to enable more personalized treatment of CB-mediated cardiovascular and respiratory disease.
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Affiliation(s)
- Hayyaf S. Aldossary
- Institute of Clinical Sciences, University of Birmingham, Birmingham B15 2TT, UK; (H.S.A.); (A.A.A.); (D.N.); (E.A.A.); (C.J.R.); (P.K.); (A.M.C.)
- College of Medicine, Basic Medical Sciences, King Saud bin Abdulaziz University for Health Sciences, Riyadh 11481, Saudi Arabia
| | - Abdulaziz A. Alzahrani
- Institute of Clinical Sciences, University of Birmingham, Birmingham B15 2TT, UK; (H.S.A.); (A.A.A.); (D.N.); (E.A.A.); (C.J.R.); (P.K.); (A.M.C.)
- Respiratory Care Department, Faculty of Applied Medical Sciences, Umm Al-Qura University, Makkah 24381, Saudi Arabia
| | - Demitris Nathanael
- Institute of Clinical Sciences, University of Birmingham, Birmingham B15 2TT, UK; (H.S.A.); (A.A.A.); (D.N.); (E.A.A.); (C.J.R.); (P.K.); (A.M.C.)
| | - Eyas A. Alhuthail
- Institute of Clinical Sciences, University of Birmingham, Birmingham B15 2TT, UK; (H.S.A.); (A.A.A.); (D.N.); (E.A.A.); (C.J.R.); (P.K.); (A.M.C.)
- Collage of Sciences and Health Professions, Basic Sciences Department, King Saud bin Abdulaziz University for Health Sciences, Riyadh 11481, Saudi Arabia
| | - Clare J. Ray
- Institute of Clinical Sciences, University of Birmingham, Birmingham B15 2TT, UK; (H.S.A.); (A.A.A.); (D.N.); (E.A.A.); (C.J.R.); (P.K.); (A.M.C.)
| | - Nikolaos Batis
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham B15 2TT, UK;
| | - Prem Kumar
- Institute of Clinical Sciences, University of Birmingham, Birmingham B15 2TT, UK; (H.S.A.); (A.A.A.); (D.N.); (E.A.A.); (C.J.R.); (P.K.); (A.M.C.)
| | - Andrew M. Coney
- Institute of Clinical Sciences, University of Birmingham, Birmingham B15 2TT, UK; (H.S.A.); (A.A.A.); (D.N.); (E.A.A.); (C.J.R.); (P.K.); (A.M.C.)
| | - Andrew P. Holmes
- Institute of Clinical Sciences, University of Birmingham, Birmingham B15 2TT, UK; (H.S.A.); (A.A.A.); (D.N.); (E.A.A.); (C.J.R.); (P.K.); (A.M.C.)
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham B15 2TT, UK
- Correspondence: ; Tel.: +44-121-415-8161
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14
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Exploring the Mediators that Promote Carotid Body Dysfunction in Type 2 Diabetes and Obesity Related Syndromes. Int J Mol Sci 2020; 21:ijms21155545. [PMID: 32756352 PMCID: PMC7432672 DOI: 10.3390/ijms21155545] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 07/26/2020] [Accepted: 07/30/2020] [Indexed: 12/12/2022] Open
Abstract
Carotid bodies (CBs) are peripheral chemoreceptors that sense changes in blood O2, CO2, and pH levels. Apart from ventilatory control, these organs are deeply involved in the homeostatic regulation of carbohydrates and lipid metabolism and inflammation. It has been described that CB dysfunction is involved in the genesis of metabolic diseases and that CB overactivation is present in animal models of metabolic disease and in prediabetes patients. Additionally, resection of the CB-sensitive nerve, the carotid sinus nerve (CSN), or CB ablation in animals prevents and reverses diet-induced insulin resistance and glucose intolerance as well as sympathoadrenal overactivity, meaning that the beneficial effects of decreasing CB activity on glucose homeostasis are modulated by target-related efferent sympathetic nerves, through a reflex initiated in the CBs. In agreement with our pre-clinical data, hyperbaric oxygen therapy, which reduces CB activity, improves glucose homeostasis in type 2 diabetes patients. Insulin, leptin, and pro-inflammatory cytokines activate the CB. In this manuscript, we review in a concise manner the putative pathways linking CB chemoreceptor deregulation with the pathogenesis of metabolic diseases and discuss and present new data that highlight the roles of hyperinsulinemia, hyperleptinemia, and chronic inflammation as major factors contributing to CB dysfunction in metabolic disorders.
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15
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Kim LJ, Polotsky VY. Carotid Body and Metabolic Syndrome: Mechanisms and Potential Therapeutic Targets. Int J Mol Sci 2020; 21:E5117. [PMID: 32698380 PMCID: PMC7404212 DOI: 10.3390/ijms21145117] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 07/11/2020] [Accepted: 07/16/2020] [Indexed: 12/19/2022] Open
Abstract
The carotid body (CB) is responsible for the peripheral chemoreflex by sensing blood gases and pH. The CB also appears to act as a peripheral sensor of metabolites and hormones, regulating the metabolism. CB malfunction induces aberrant chemosensory responses that culminate in the tonic overactivation of the sympathetic nervous system. The sympatho-excitation evoked by CB may contribute to the pathogenesis of metabolic syndrome, inducing systemic hypertension, insulin resistance and sleep-disordered breathing. Several molecular pathways are involved in the modulation of CB activity, and their pharmacological manipulation may lead to overall benefits for cardiometabolic diseases. In this review, we will discuss the role of the CB in the regulation of metabolism and in the pathogenesis of the metabolic dysfunction induced by CB overactivity. We will also explore the potential pharmacological targets in the CB for the treatment of metabolic syndrome.
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Affiliation(s)
- Lenise J. Kim
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, School of Medicine, Johns Hopkins University, Baltimore, MD 21224, USA;
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16
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Abstract
The carotid body (CB) is an arterial chemoreceptor organ located in the carotid bifurcation and has a well-recognized role in cardiorespiratory regulation. The CB contains neurosecretory sensory cells (glomus cells), which release transmitters in response to hypoxia, hypercapnia, and acidemia to activate afferent sensory fibers terminating in the respiratory and autonomic brainstem centers. Knowledge of the physiology of the CB has progressed enormously in recent years. Herein we review advances concerning the organization and function of the cellular elements of the CB, with emphasis on the molecular mechanisms of acute oxygen sensing by glomus cells. We introduce the modern view of the CB as a multimodal integrated metabolic sensor and describe the properties of the CB stem cell niche, which support CB growth during acclimatization to chronic hypoxia. Finally, we discuss the increasing medical relevance of CB dysfunction and its potential impact on the mechanisms of disease.
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Affiliation(s)
- Patricia Ortega-Sáenz
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla 41013, Spain; , .,Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, Sevilla 41009, Spain.,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Sevilla 41013, Spain
| | - José López-Barneo
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla 41013, Spain; , .,Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, Sevilla 41009, Spain.,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Sevilla 41013, Spain
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17
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Limberg JK, Johnson BD, Mozer MT, Holbein WW, Curry TB, Prabhakar NR, Joyner MJ. Role of the carotid chemoreceptors in insulin-mediated sympathoexcitation in humans. Am J Physiol Regul Integr Comp Physiol 2019; 318:R173-R181. [PMID: 31746629 DOI: 10.1152/ajpregu.00257.2019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We examined the contribution of the carotid chemoreceptors to insulin-mediated increases in muscle sympathetic nerve activity (MSNA) in healthy humans. We hypothesized that reductions in carotid chemoreceptor activity would attenuate the sympathoexcitatory response to hyperinsulinemia. Young, healthy adults (9 male/9 female, 28 ± 1 yr, 24 ± 1 kg/m2) completed a 30-min euglycemic baseline followed by a 90-min hyperinsulinemic (1 mU·kg fat-free mass-1·min-1), euglycemic infusion. MSNA (microneurography of the peroneal nerve) was continuously measured. The role of the carotid chemoreceptors was assessed at baseline and during hyperinsulinemia via 1) acute hyperoxia, 2) low-dose dopamine (1-4 µg·kg-1·min-1), and 3) acute hyperoxia + low-dose dopamine. MSNA burst frequency increased from baseline during hyperinsulinemia (P < 0.01). Acute hyperoxia had no effect on MSNA burst frequency at rest (P = 0.74) or during hyperinsulinemia (P = 0.83). The insulin-mediated increase in MSNA burst frequency (P = 0.02) was unaffected by low-dose dopamine (P = 0.60). When combined with low-dose dopamine, acute hyperoxia had no effect on MSNA burst frequency at rest (P = 0.17) or during hyperinsulinemia (P = 0.85). Carotid chemoreceptor desensitization in young, healthy men and women does not attenuate the sympathoexcitatory response to hyperinsulinemia. Our data suggest that the carotid chemoreceptors do not contribute to acute insulin-mediated increases in MSNA in young, healthy adults.
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Affiliation(s)
- Jacqueline K Limberg
- Department of Anesthesiology, Mayo Clinic, Rochester, Minnesota.,Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri
| | - Blair D Johnson
- Department of Anesthesiology, Mayo Clinic, Rochester, Minnesota.,Department of Exercise and Nutrition Sciences, University at Buffalo, Buffalo, New York
| | - Michael T Mozer
- Department of Anesthesiology, Mayo Clinic, Rochester, Minnesota
| | | | - Timothy B Curry
- Department of Anesthesiology, Mayo Clinic, Rochester, Minnesota
| | - Nanduri R Prabhakar
- Institute for Integrative Physiology, School of Medicine, University of Chicago, Chicago, Illinois
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18
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Holmes AP, Ray CJ, Thompson EL, Alshehri Z, Coney AM, Kumar P. Adrenaline activation of the carotid body: Key to CO 2 and pH homeostasis in hypoglycaemia and potential pathological implications in cardiovascular disease. Respir Physiol Neurobiol 2018; 265:92-99. [PMID: 29807139 DOI: 10.1016/j.resp.2018.05.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Revised: 05/17/2018] [Accepted: 05/21/2018] [Indexed: 12/30/2022]
Abstract
Ventilatory and neuroendocrine counter-regulatory responses during hypoglycaemia are essential in order to maintain glycolysis and prevent rises in PaCO2 leading to systemic acidosis. The mammalian carotid body has emerged as an important driver of hyperpnoea and glucoregulation in hypoglycaemia. However, the adequate stimulus for CB stimulation in hypoglycaemia has remained controversial for over a decade. The recent finding that adrenaline is a physiological activator of CB in hypoglycaemia raises the intriguing possibility that CB stimulation and hyperpnoea may be necessary to maintain pH in other adrenaline-related hypermetabolic states such as exercise. This review will therefore focus on 1) The important functional contribution of the CB in the counter-regulatory and ventilatory response to hypoglycaemia, 2) the proposed mechanisms that cause CB stimulation in hypoglycaemia including hormonal activation by adrenaline and direct low glucose sensing and 3) the possible pathological consequences of repetitive CB activation by adrenaline that could potentially be targeted to reduce CB-mediated cardiovascular disease.
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Affiliation(s)
- Andrew P Holmes
- Institute of Clinical Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B12 2TT, UK
| | - Clare J Ray
- Institute of Clinical Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B12 2TT, UK
| | - Emma L Thompson
- Institute of Clinical Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B12 2TT, UK
| | - Ziyad Alshehri
- Institute of Clinical Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B12 2TT, UK
| | - Andrew M Coney
- Institute of Clinical Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B12 2TT, UK
| | - Prem Kumar
- Institute of Clinical Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B12 2TT, UK.
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19
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Abstract
Known primarily for its oxygen-sensing capabilities, the carotid body chemoreceptors have recently been implicated, primarily by work in animal models, in the pathophysiology of a number of metabolic conditions. The research presented in this brief review highlights translational work conducted at the Mayo Clinic between 2010 and 2017 in healthy humans and discusses key areas for future work in disease populations.
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Affiliation(s)
- Jacqueline K Limberg
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota and Department of Nutrition and Exercise Physiology, University of Missouri , Columbia, Missouri
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20
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Barbosa TC, Kaur J, Holwerda SW, Young CN, Curry TB, Thyfault JP, Joyner MJ, Limberg JK, Fadel PJ. Insulin increases ventilation during euglycemia in humans. Am J Physiol Regul Integr Comp Physiol 2018; 315:R84-R89. [PMID: 29590558 DOI: 10.1152/ajpregu.00039.2018] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Evidence from animal studies indicates that hyperinsulinemia, without changes in glucose, increases ventilation via a carotid body-mediated mechanism. However, whether insulin elevates ventilation in humans independently of changes in glucose remains unclear. Therefore, we tested the hypothesis that insulin increases ventilation in humans during a hyperinsulinemic-euglycemic clamp in which insulin was elevated to postprandial concentrations while glucose was maintained at fasting concentrations. First, in 16 healthy young men ( protocol 1), we retrospectively analyzed respiration rate and estimated tidal volume from a pneumobelt to calculate minute ventilation during a hyperinsulinemic-euglycemic clamp. In addition, for a direct assessment of minute ventilation during a hyperinsulinemic-euglycemic clamp, we retrospectively analyzed breath-by-breath respiration rate and tidal volume from inspired/expired gasses in an additional 23 healthy young subjects ( protocol 2). Clamp infusion elevated minute ventilation from baseline in both protocols ( protocol 1: +11.9 ± 4.6% baseline, P = 0.001; protocol 2: +9.5 ± 3.8% baseline, P = 0.020). In protocol 1, peak changes in both respiration rate (+13.9 ± 3.0% baseline, P < 0.001) and estimated tidal volume (+16.9 ± 4.1% baseline, P = 0.001) were higher than baseline during the clamp. In protocol 2, tidal volume primarily increased during the clamp (+9.7 ± 3.7% baseline, P = 0.016), as respiration rate did not change significantly (+0.2 ± 1.8% baseline, P = 0.889). Collectively, we demonstrate for the first time in humans that elevated plasma insulin increases minute ventilation independent of changes in glucose.
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Affiliation(s)
- Thales C Barbosa
- Department of Kinesiology, University of Texas Arlington , Arlington, Texas
| | - Jasdeep Kaur
- Department of Kinesiology, University of Texas Arlington , Arlington, Texas
| | - Seth W Holwerda
- Department of Health and Human Physiology, University of Iowa , Iowa City, Iowa
| | - Colin N Young
- Department of Pharmacology & Physiology, George Washington University School of Medicine and Health Sciences , Washington, District of Columbia
| | - Timothy B Curry
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic , Rochester, Minnesota
| | - John P Thyfault
- Department of Molecular and Integrative Physiology, University of Kansas Medical Center , Kansas City, Kansas
| | - Michael J Joyner
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic , Rochester, Minnesota
| | - Jacqueline K Limberg
- Department of Nutrition and Exercise Physiology, University of Missouri , Columbia, Missouri
| | - Paul J Fadel
- Department of Kinesiology, University of Texas Arlington , Arlington, Texas
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21
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Joyner MJ, Limberg JK, Wehrwein EA, Johnson BD. Role of the carotid body chemoreceptors in glucose homeostasis and thermoregulation in humans. J Physiol 2018; 596:3079-3085. [PMID: 29377157 DOI: 10.1113/jp274354] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Accepted: 01/02/2018] [Indexed: 01/03/2023] Open
Abstract
The carotid bodies (CBs) are multi-modal sensory organs located bilaterally at the bifurcation of the carotid artery and innervated by the carotid sinus nerve (Hering's nerve), a branch of the IX cranial nerve. While the CBs (or embryologically analogous structures) are well known as the dominant oxygen-sensing organ in vertebrates, in mammals there is evidence that the CBs may also sense glucose and temperature, and respond to circulating hormones and other factors. Additionally, the CBs likely participate in regulating baseline levels of sympathetic tone. In this brief review, we focus on the evolution of our efforts to understand 'what else' beyond oxygen sensing the CBs do in humans.
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Affiliation(s)
- Michael J Joyner
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, MN, USA
| | - Jacqueline K Limberg
- Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, MO 65211, USA
| | - Erica A Wehrwein
- Department of Physiology, Michigan State University, East Lansing, MI 48823, USA
| | - Blair D Johnson
- Center for Research and Education in Special Environments, Department of Exercise and Nutrition Sciences, University at Buffalo, Buffalo, NY, USA
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22
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Conde SV, Sacramento JF, Guarino MP. Carotid body: a metabolic sensor implicated in insulin resistance. Physiol Genomics 2018; 50:208-214. [PMID: 29373079 DOI: 10.1152/physiolgenomics.00121.2017] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The carotid body is now looked at as a multipurpose sensor for blood gases, blood pH, and several hormones. The matter of glucose sensing by the carotid body has been debated for several years in the literature, and these days there is a consensus that carotid body activity is modified by metabolic factors that contribute to glucose homeostasis. However, the sensing ability for glucose is still being pondered: are the carotid bodies low glucose sensors or, in contrast, are they overresponsive in high-glucose conditions? Herein, we debate the glucose and insulin sensing capabilities of the carotid body as key early events in the overactivation of the carotid body, which is increasingly recognized as an important feature of metabolic diseases. Additionally, we dedicate a final section to discuss new outside-the-box therapies designed to decrease carotid body activity that may be used for treating metabolic diseases.
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Affiliation(s)
- Silvia V Conde
- CEDOC, NOVA Medical School, Faculdade de Ciências, Universidade NOVA de Lisboa , Lisbon , Portugal
| | - Joana F Sacramento
- CEDOC, NOVA Medical School, Faculdade de Ciências, Universidade NOVA de Lisboa , Lisbon , Portugal
| | - Maria P Guarino
- CEDOC, NOVA Medical School, Faculdade de Ciências, Universidade NOVA de Lisboa , Lisbon , Portugal.,School of Health Sciences, Polytechnic Institute of Leiria , Leiria , Portugal
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23
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Hildebrandt W, Sauer R, Koehler U, Bärtsch P, Kinscherf R. Lower hypoxic ventilatory response in smokers compared to non-smokers during abstinence from cigarettes. BMC Pulm Med 2016; 16:159. [PMID: 27881161 PMCID: PMC5121951 DOI: 10.1186/s12890-016-0323-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Accepted: 11/15/2016] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Carotid body O2-chemosensitivity determines the hypoxic ventilatory response (HVR) as part of crucial regulatory reflex within oxygen homeostasis. Nicotine has been suggested to attenuate HVR in neonates of smoking mothers. However, whether smoking affects HVR in adulthood has remained unclear and probably blurred by acute ventilatory stimulation through cigarette smoke. We hypothesized that HVR is substantially reduced in smokers when studied after an overnight abstinence from cigarettes i.e. after nicotine elimination. METHODS We therefore determined the isocapnic HVR of 23 healthy male smokers (age 33.9 ± 2.0 years, BMI 24.2 ± 0.5 kg m-2, mean ± SEM) with a smoking history of >8 years after 12 h of abstinence and compared it to that of 23 healthy male non-smokers matched for age and BMI. RESULTS Smokers and non-smokers were comparable with regard to factors known to affect isocapnic HVR such as plasma levels of glucose and thiols as well as intracellular levels of glutathione in blood mononuclear cells. As a new finding, abstinent smokers had a significantly lower isocapnic HVR (0.024 ± 0.002 vs. 0.037 ± 0.003 l min-1 %-1BMI-1, P = 0.002) compared to non-smokers. However, upon re-exposure to cigarettes the smokers' HVR increased immediately to the non-smokers' level. CONCLUSIONS This is the first report of a substantial HVR reduction in abstinent adult smokers which appears to be masked by daily smoking routine and may therefore have been previously overlooked. A low HVR may be suggested as a novel link between smoking and aggravated hypoxemia during sleep especially in relevant clinical conditions such as COPD.
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Affiliation(s)
- Wulf Hildebrandt
- Former Department of Immunochemistry, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 60120, Heidelberg, Germany. .,Department of Medical Cell Biology, Institute of Anatomy and Cell Biology, University of Marburg, Robert-Koch-Straße 8, D-35032, Marburg, Germany.
| | - Roland Sauer
- Former Department of Immunochemistry, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 60120, Heidelberg, Germany.,Department of Neurology, University Hospital Erlangen, Schwabachanlage 6, 91054, Erlangen, Germany
| | - Ulrich Koehler
- Sleep Disorder Unit, Department of Pneumology, University Hospital Marburg, Baldingerstraße, 35043, Marburg, Germany
| | - Peter Bärtsch
- Division VII (Sports Medicine), Medical University Clinic, University of Heidelberg, Im Neuenheimer Feld 410, D-69120, Heidelberg, Germany
| | - Ralf Kinscherf
- Department of Medical Cell Biology, Institute of Anatomy and Cell Biology, University of Marburg, Robert-Koch-Straße 8, D-35032, Marburg, Germany
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Shatylo VB, Serebrovska TV, Gavalko AV, Egorov E, Korkushko OV. Acute Hypoxic Test in Patients with Prediabetes. High Alt Med Biol 2016; 17:101-7. [DOI: 10.1089/ham.2015.0117] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Affiliation(s)
- Valerii B. Shatylo
- Department of Physiology and Pathology of Internal Organs, D.F. Chebotarev State Institute of Gerontology, Kiev, Ukraine
| | | | - Anna V. Gavalko
- Department of Physiology and Pathology of Internal Organs, D.F. Chebotarev State Institute of Gerontology, Kiev, Ukraine
| | | | - Oleg V. Korkushko
- Department of Physiology and Pathology of Internal Organs, D.F. Chebotarev State Institute of Gerontology, Kiev, Ukraine
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25
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Thompson EL, Ray CJ, Holmes AP, Pye RL, Wyatt CN, Coney AM, Kumar P. Adrenaline release evokes hyperpnoea and an increase in ventilatory CO2 sensitivity during hypoglycaemia: a role for the carotid body. J Physiol 2016; 594:4439-52. [PMID: 27027261 DOI: 10.1113/jp272191] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2016] [Accepted: 03/18/2016] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Hypoglycaemia is counteracted by release of hormones and an increase in ventilation and CO2 sensitivity to restore blood glucose levels and prevent a fall in blood pH. The full counter-regulatory response and an appropriate increase in ventilation is dependent on carotid body stimulation. We show that the hypoglycaemia-induced increase in ventilation and CO2 sensitivity is abolished by preventing adrenaline release or blocking its receptors. Physiological levels of adrenaline mimicked the effect of hypoglycaemia on ventilation and CO2 sensitivity. These results suggest that adrenaline, rather than low glucose, is an adequate stimulus for the carotid body-mediated changes in ventilation and CO2 sensitivity during hypoglycaemia to prevent a serious acidosis in poorly controlled diabetes. ABSTRACT Hypoglycaemia in vivo induces a counter-regulatory response that involves the release of hormones to restore blood glucose levels. Concomitantly, hypoglycaemia evokes a carotid body-mediated hyperpnoea that maintains arterial CO2 levels and prevents respiratory acidosis in the face of increased metabolism. It is unclear whether the carotid body is directly stimulated by low glucose or by a counter-regulatory hormone such as adrenaline. Minute ventilation was recorded during infusion of insulin-induced hypoglycaemia (8-17 mIU kg(-1) min(-1) ) in Alfaxan-anaesthetised male Wistar rats. Hypoglycaemia significantly augmented minute ventilation (123 ± 4 to 143 ± 7 ml min(-1) ) and CO2 sensitivity (3.3 ± 0.3 to 4.4 ± 0.4 ml min(-1) mmHg(-1) ). These effects were abolished by either β-adrenoreceptor blockade with propranolol or adrenalectomy. In this hypermetabolic, hypoglycaemic state, propranolol stimulated a rise in P aC O2, suggestive of a ventilation-metabolism mismatch. Infusion of adrenaline (1 μg kg(-1) min(-1) ) increased minute ventilation (145 ± 4 to 173 ± 5 ml min(-1) ) without altering P aC O2 or pH and enhanced ventilatory CO2 sensitivity (3.4 ± 0.4 to 5.1 ± 0.8 ml min(-1) mmHg(-1) ). These effects were attenuated by either resection of the carotid sinus nerve or propranolol. Physiological concentrations of adrenaline increased the CO2 sensitivity of freshly dissociated carotid body type I cells in vitro. These findings suggest that adrenaline release can account for the ventilatory hyperpnoea observed during hypoglycaemia by an augmented carotid body and whole body ventilatory CO2 sensitivity.
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Affiliation(s)
- Emma L Thompson
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Clare J Ray
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK.,Institute of Clinical Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Andrew P Holmes
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Richard L Pye
- Department of Neuroscience, Cell Biology and Physiology, Wright State University, Dayton, OH, USA
| | - Christopher N Wyatt
- Department of Neuroscience, Cell Biology and Physiology, Wright State University, Dayton, OH, USA
| | - Andrew M Coney
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK.,Institute of Clinical Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Prem Kumar
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK.,Institute of Clinical Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
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26
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López-Barneo J, González-Rodríguez P, Gao L, Fernández-Agüera MC, Pardal R, Ortega-Sáenz P. Oxygen sensing by the carotid body: mechanisms and role in adaptation to hypoxia. Am J Physiol Cell Physiol 2016; 310:C629-42. [PMID: 26764048 DOI: 10.1152/ajpcell.00265.2015] [Citation(s) in RCA: 93] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Oxygen (O2) is fundamental for cell and whole-body homeostasis. Our understanding of the adaptive processes that take place in response to a lack of O2(hypoxia) has progressed significantly in recent years. The carotid body (CB) is the main arterial chemoreceptor that mediates the acute cardiorespiratory reflexes (hyperventilation and sympathetic activation) triggered by hypoxia. The CB is composed of clusters of cells (glomeruli) in close contact with blood vessels and nerve fibers. Glomus cells, the O2-sensitive elements in the CB, are neuron-like cells that contain O2-sensitive K(+)channels, which are inhibited by hypoxia. This leads to cell depolarization, Ca(2+)entry, and the release of transmitters to activate sensory fibers terminating at the respiratory center. The mechanism whereby O2modulates K(+)channels has remained elusive, although several appealing hypotheses have been postulated. Recent data suggest that mitochondria complex I signaling to membrane K(+)channels plays a fundamental role in acute O2sensing. CB activation during exposure to low Po2is also necessary for acclimatization to chronic hypoxia. CB growth during sustained hypoxia depends on the activation of a resident population of stem cells, which are also activated by transmitters released from the O2-sensitive glomus cells. These advances should foster further studies on the role of CB dysfunction in the pathogenesis of highly prevalent human diseases.
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Affiliation(s)
- José López-Barneo
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío, CSIC, Universidad de Sevilla, Seville, Spain; Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, Seville, Spain; and Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Patricia González-Rodríguez
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío, CSIC, Universidad de Sevilla, Seville, Spain; Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, Seville, Spain; and Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Lin Gao
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío, CSIC, Universidad de Sevilla, Seville, Spain; Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, Seville, Spain; and Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - M Carmen Fernández-Agüera
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío, CSIC, Universidad de Sevilla, Seville, Spain; Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, Seville, Spain; and Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Ricardo Pardal
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío, CSIC, Universidad de Sevilla, Seville, Spain; Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, Seville, Spain; and Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Patricia Ortega-Sáenz
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío, CSIC, Universidad de Sevilla, Seville, Spain; Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, Seville, Spain; and Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
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Prabhakhar NR, Joyner MJ. Tasting arterial blood: what do the carotid chemoreceptors sense? Front Physiol 2015; 5:524. [PMID: 25642193 PMCID: PMC4294136 DOI: 10.3389/fphys.2014.00524] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Accepted: 12/20/2014] [Indexed: 01/16/2023] Open
Abstract
The carotid bodies are sensory organs that detect the chemical composition of the arterial blood. The carotid body sensory activity increases in response to arterial hypoxemia and the ensuing chemoreflex regulates vital homeostatic functions. Recent studies suggest that the carotid bodies might also sense arterial blood glucose and circulating insulin levels. This review focuses on how the carotid bodies sense O2, glucose, and insulin and some potential implications of these sensory functions on physiological regulation and in pathophysiological conditions. Emerging evidence suggests that carbon monoxide (CO)-regulated hydrogen sulfide (H2S), stemming from hypoxia, depolarizes type I cells by inhibiting certain K+ channels, facilitates voltage-gated Ca2+ influx leading to sensory excitation of the carotid body. Elevated CO and decreased H2S renders the carotid bodies insensitive to hypoxia resulting in attenuated ventilatory adaptations to high altitude hypoxia, whereas reduced CO and high H2S result in hypersensitivity of the carotid bodies to hypoxia and hypertension. Acute hypoglycemia augments the carotid body responses to hypoxia but that a prolonged lack of glucose in the carotid bodies can lead to a failure to sense hypoxia. Emerging evidence also indicates that carotid bodies might sense insulin directly independent of its effect on glucose, linking the carotid bodies to the pathophysiological consequences of the metabolic syndrome. How glucose and insulin interact with the CO-H2S signaling is an area of ongoing study.
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Affiliation(s)
- Nanduri R Prabhakhar
- Institute for Integrative Physiology, Center for Systems Biology of O2 Sensing, The University of Chicago Chicago, IL, USA
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28
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Conde SV, Sacramento JF, Guarino MP, Gonzalez C, Obeso A, Diogo LN, Monteiro EC, Ribeiro MJ. Carotid body, insulin, and metabolic diseases: unraveling the links. Front Physiol 2014; 5:418. [PMID: 25400585 PMCID: PMC4212612 DOI: 10.3389/fphys.2014.00418] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Accepted: 10/10/2014] [Indexed: 11/13/2022] Open
Abstract
The carotid bodies (CB) are peripheral chemoreceptors that sense changes in arterial blood O2, CO2, and pH levels. Hypoxia, hypercapnia, and acidosis activate the CB, which respond by increasing the action potential frequency in their sensory nerve, the carotid sinus nerve (CSN). CSN activity is integrated in the brain stem to induce a panoply of cardiorespiratory reflexes aimed, primarily, to normalize the altered blood gases, via hyperventilation, and to regulate blood pressure and cardiac performance, via sympathetic nervous system (SNS) activation. Besides its role in the cardiorespiratory control the CB has been proposed as a metabolic sensor implicated in the control of energy homeostasis and, more recently, in the regulation of whole body insulin sensitivity. Hypercaloric diets cause CB overactivation in rats, which seems to be at the origin of the development of insulin resistance and hypertension, core features of metabolic syndrome and type 2 diabetes. Consistent with this notion, CB sensory denervation prevents metabolic and hemodynamic alterations in hypercaloric feed animal. Obstructive sleep apnea (OSA) is another chronic disorder characterized by increased CB activity and intimately related with several metabolic and cardiovascular abnormalities. In this manuscript we review in a concise manner the putative pathways linking CB chemoreceptors deregulation with the pathogenesis of insulin resistance and arterial hypertension. Also, the link between chronic intermittent hypoxia (CIH) and insulin resistance is discussed. Then, a final section is devoted to debate strategies to reduce CB activity and its use for prevention and therapeutics of metabolic diseases with an emphasis on new exciting research in the modulation of bioelectronic signals, likely to be central in the future.
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Affiliation(s)
- Sílvia V Conde
- CEDOC, Centro Estudos Doenças Crónicas, NOVA Medical School, Faculdade de Ciências Médicas, Universidade Nova de Lisboa Lisboa, Portugal
| | - Joana F Sacramento
- CEDOC, Centro Estudos Doenças Crónicas, NOVA Medical School, Faculdade de Ciências Médicas, Universidade Nova de Lisboa Lisboa, Portugal
| | - Maria P Guarino
- CEDOC, Centro Estudos Doenças Crónicas, NOVA Medical School, Faculdade de Ciências Médicas, Universidade Nova de Lisboa Lisboa, Portugal ; Health Research Unit - UIS, School of Health Sciences, Polytechnic Institute of Leiria Leiria, Portugal
| | - Constancio Gonzalez
- Departamento de Bioquímica y Biología Molecular y Fisiología, Facultad de Medicina, Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas, Ciber de Enfermedades Respiratorias, CIBERES, Instituto de Salud Carlos III, Universidad de Valladolid Valladolid, España
| | - Ana Obeso
- Departamento de Bioquímica y Biología Molecular y Fisiología, Facultad de Medicina, Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas, Ciber de Enfermedades Respiratorias, CIBERES, Instituto de Salud Carlos III, Universidad de Valladolid Valladolid, España
| | - Lucilia N Diogo
- CEDOC, Centro Estudos Doenças Crónicas, NOVA Medical School, Faculdade de Ciências Médicas, Universidade Nova de Lisboa Lisboa, Portugal
| | - Emilia C Monteiro
- CEDOC, Centro Estudos Doenças Crónicas, NOVA Medical School, Faculdade de Ciências Médicas, Universidade Nova de Lisboa Lisboa, Portugal
| | - Maria J Ribeiro
- CEDOC, Centro Estudos Doenças Crónicas, NOVA Medical School, Faculdade de Ciências Médicas, Universidade Nova de Lisboa Lisboa, Portugal
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Holmes AP, Turner PJ, Carter P, Leadbeater W, Ray CJ, Hauton D, Buckler KJ, Kumar P. Glycogen metabolism protects against metabolic insult to preserve carotid body function during glucose deprivation. J Physiol 2014; 592:4493-506. [PMID: 25063821 PMCID: PMC4287740 DOI: 10.1113/jphysiol.2014.276105] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Accepted: 07/07/2014] [Indexed: 01/08/2023] Open
Abstract
The view that the carotid body (CB) type I cells are direct physiological sensors of hypoglycaemia is challenged by the finding that the basal sensory neuronal outflow from the whole organ is unchanged in response to low glucose. The reason for this difference in viewpoint and how the whole CB maintains its metabolic integrity when exposed to low glucose is unknown. Here we show that, in the intact superfused rat CB, basal sensory neuronal activity was sustained during glucose deprivation for 29.1 ± 1.2 min, before irreversible failure following a brief period of excitation. Graded increases in the basal discharge induced by reducing the superfusate PO2 led to proportional decreases in the time to the pre-failure excitation during glucose deprivation which was dependent on a complete run-down in glycolysis and a fall in cellular energy status. A similar ability to withstand prolonged glucose deprivation was observed in isolated type I cells. Electron micrographs and immunofluorescence staining of rat CB sections revealed the presence of glycogen granules and the glycogen conversion enzymes glycogen synthase I and glycogen phosphorylase BB, dispersed throughout the type I cell cytoplasm. Furthermore, pharmacological attenuation of glycogenolysis and functional depletion of glycogen both significantly reduced the time to glycolytic run-down by ∼33 and 65%, respectively. These findings suggest that type I cell glycogen metabolism allows for the continuation of glycolysis and the maintenance of CB sensory neuronal output in periods of restricted glucose delivery and this may act as a key protective mechanism for the organ during hypoglycaemia. The ability, or otherwise, to preserve energetic status may thus account for variation in the reported capacity of the CB to sense physiological glucose concentrations and may even underlie its function during pathological states associated with augmented CB discharge.
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Affiliation(s)
- Andrew P Holmes
- School of Clinical and Experimental Medicine, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Philip J Turner
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT, UK
| | - Paul Carter
- School of Clinical and Experimental Medicine, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Wendy Leadbeater
- School of Clinical and Experimental Medicine, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Clare J Ray
- School of Clinical and Experimental Medicine, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - David Hauton
- School of Clinical and Experimental Medicine, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Keith J Buckler
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT, UK
| | - Prem Kumar
- School of Clinical and Experimental Medicine, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
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30
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Gao L, Ortega-Sáenz P, García-Fernández M, González-Rodríguez P, Caballero-Eraso C, López-Barneo J. Glucose sensing by carotid body glomus cells: potential implications in disease. Front Physiol 2014; 5:398. [PMID: 25360117 PMCID: PMC4197775 DOI: 10.3389/fphys.2014.00398] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Accepted: 09/25/2014] [Indexed: 01/22/2023] Open
Abstract
The carotid body (CB) is a key chemoreceptor organ in which glomus cells sense changes in blood O2, CO2, and pH levels. CB glomus cells have also been found to detect hypoglycemia in both non-primate mammals and humans. O2 and low-glucose responses share a common final pathway involving membrane depolarization, extracellular calcium influx, increase in cytosolic calcium concentration, and neurotransmitter secretion, which stimulates afferent sensory fibers to evoke sympathoadrenal activation. On the other hand, hypoxia and low glucose induce separate signal transduction pathways. Unlike O2 sensing, the response of the CB to low glucose is not altered by rotenone, with the low glucose-activated background cationic current unaffected by hypoxia. Responses of the CB to hypoglycemia and hypoxia can be potentiated by each other. The counter-regulatory response to hypoglycemia by the CB is essential for the brain, an organ that is particularly sensitive to low glucose. CB glucose sensing could be altered in diabetic patients, particularly those under insulin treatment, as well as in other medical conditions such as sleep apnea or obstructive pulmonary diseases, where chronic hypoxemia presents with plastic modifications in CB structure and function. The current review will focus on the following main aspects: (1) the CB as a low glucose sensor in both in vitro and in vivo models; (2) molecular and ionic mechanisms of low glucose sensing by glomus cells, (3) the interplay between low glucose and O2 sensing in CB, and (4) the role of CB low glucose sensing in the pathophysiology of cardiorespiratory and metabolic diseases, and how this may serve as a potential therapeutic target.
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Affiliation(s)
- Lin Gao
- Instituto de Biomedicina de Sevilla, Hospital Universitario Virgen del Rocío/Consejo Superior de Investigaciones Científicas/Universidad de Sevilla Seville, Spain ; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas Seville, Spain
| | - Patricia Ortega-Sáenz
- Instituto de Biomedicina de Sevilla, Hospital Universitario Virgen del Rocío/Consejo Superior de Investigaciones Científicas/Universidad de Sevilla Seville, Spain ; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas Seville, Spain ; Departamento de Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla Seville, Spain
| | - María García-Fernández
- Departamento de Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla Seville, Spain
| | - Patricia González-Rodríguez
- Instituto de Biomedicina de Sevilla, Hospital Universitario Virgen del Rocío/Consejo Superior de Investigaciones Científicas/Universidad de Sevilla Seville, Spain ; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas Seville, Spain
| | - Candela Caballero-Eraso
- Instituto de Biomedicina de Sevilla, Hospital Universitario Virgen del Rocío/Consejo Superior de Investigaciones Científicas/Universidad de Sevilla Seville, Spain ; Unidad Médico-Quirúrgica de Enfermedades Respiratorias, Hospital Universitario Virgen del Rocío Seville, Spain
| | - José López-Barneo
- Instituto de Biomedicina de Sevilla, Hospital Universitario Virgen del Rocío/Consejo Superior de Investigaciones Científicas/Universidad de Sevilla Seville, Spain ; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas Seville, Spain ; Departamento de Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla Seville, Spain
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31
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Limberg JK, Curry TB, Prabhakar NR, Joyner MJ. Is insulin the new intermittent hypoxia? Med Hypotheses 2014; 82:730-5. [PMID: 24690299 DOI: 10.1016/j.mehy.2014.03.014] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Revised: 02/05/2014] [Accepted: 03/08/2014] [Indexed: 12/20/2022]
Abstract
The sympathoexcitatory effects of insulin are well-established, although the exact mechanisms by which insulin stimulates the sympathetic nervous system are not completely understood. The majority of research supports a primary role for the central nervous system in the gradual and sustained rise in muscle sympathetic nerve activity (MSNA) in response to hyperinsulinemia; in addition, recent studies in animals suggests carotid body chemoreceptors respond to increases in systemic insulin levels. Intermittent activation of the carotid chemoreceptors, similar to that seen in patients with sleep apnea, can result in sensory long term facilitation and may contribute to the observed rise in baseline MSNA in this population. Consistent with this idea, insulin exposure results in sustained increases in MSNA that persist even when plasma insulin levels return to baseline. We propose the carotid chemoreceptors contribute to insulin-mediated sympathoexcitation and the persistent rise in MSNA in patients with sustained hyperinsulinemia. If the carotid chemoreceptors sense and respond to changes in systemic insulin levels, these organs may provide a viable target for the treatment of disorders known to exhibit sustained hyperinsulinemia and sympathoexcitation including, but not limited to, obesity, hypertension, sleep apnea, metabolic syndrome, cardiovascular disease, and diabetes.
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Affiliation(s)
| | - Timothy B Curry
- Department of Anesthesiology, Mayo Clinic, Rochester, MN 55905, United States
| | - Nanduri R Prabhakar
- Institute for Integrative Physiology and The Center for Systems Biology of Oxygen Sensing, Biological Science Division, University of Chicago, Chicago, IL 60637, United States
| | - Michael J Joyner
- Department of Anesthesiology, Mayo Clinic, Rochester, MN 55905, United States.
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32
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Limberg JK, Taylor JL, Dube S, Basu R, Basu A, Joyner MJ, Wehrwein EA. Role of the carotid body chemoreceptors in baroreflex control of blood pressure during hypoglycaemia in humans. Exp Physiol 2014; 99:640-50. [PMID: 24414173 DOI: 10.1113/expphysiol.2013.076869] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Activation of the carotid body chemoreceptors with hypoxia alters baroreceptor-mediated responses. We aimed to examine whether this relationship can be translated to other chemoreceptor stimuli (i.e. hypoglycaemia) by testing the following hypotheses: (i) activation of the carotid body chemoreceptors with hypoglycaemia would reduce spontaneous cardiac baroreflex sensitivity (sCBRS) in healthy humans; and (ii) desensitization of the carotid chemoreceptors with hyperoxia would restore sCBRS to baseline levels during hypoglycaemia. Ten young healthy adults completed two 180 min hyperinsulinaemic [2 mU (kg fat-free mass)(-1) min(-1)], hypoglycaemic (∼ 3.2 μmol ml(-1)) clamps, separated by at least 1 week and randomized to normoxia (arterial partial pressure of O2, 122 ± 10 mmHg) or hyperoxia (arterial partial pressure of O2, 424 ± 123 mmHg; to blunt activation of the carotid body glomus cells). Changes in heart rate, blood pressure, plasma catecholamines, heart rate variability (HRV) and sCBRS were assessed. During hypoglycaemia, HRV and sCBRS were reduced (P < 0.05) and the baroreflex working range was shifted to higher heart rates. When hyperoxia was superimposed on hypoglycaemia, there was a greater reduction in blood pressure and a blunted rise in heart rate when compared with normoxic conditions (P < 0.05); however, there was no detectable effect of hyperoxia on sCBRS or HRV during hypoglycaemia (P > 0.05). In summary, hypoglycaemia-mediated changes in HRV and sCBRS cannot be attributed exclusively to the carotid chemoreceptors; however, the chemoreceptors appear to play a role in resetting the baroreflex working range during hypoglycaemia.
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Affiliation(s)
- Jacqueline K Limberg
- * Department of Anesthesiology, Mayo Clinic, 200 1st Street SW, SMH Joseph 4-184, Rochester, MN 55905, USA.
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Ortega-Sáenz P, Pardal R, Levitsky K, Villadiego J, Muñoz-Manchado AB, Durán R, Bonilla-Henao V, Arias-Mayenco I, Sobrino V, Ordóñez A, Oliver M, Toledo-Aral JJ, López-Barneo J. Cellular properties and chemosensory responses of the human carotid body. J Physiol 2013; 591:6157-73. [PMID: 24167224 DOI: 10.1113/jphysiol.2013.263657] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The carotid body (CB) is the major peripheral arterial chemoreceptor in mammals that mediates the acute hyperventilatory response to hypoxia. The CB grows in response to sustained hypoxia and also participates in acclimatisation to chronic hypoxaemia. Knowledge of CB physiology at the cellular level has increased considerably in recent times thanks to studies performed on lower mammals, and rodents in particular. However, the functional characteristics of human CB cells remain practically unknown. Herein, we use tissue slices or enzymatically dispersed cells to determine the characteristics of human CB cells. The adult human CB parenchyma contains clusters of chemosensitive glomus (type I) and sustentacular (type II) cells as well as nestin-positive progenitor cells. This organ also expresses high levels of the dopaminotrophic glial cell line-derived neurotrophic factor (GDNF). We found that GDNF production and the number of progenitor and glomus cells were preserved in the CBs of human subjects of advanced age. Moreover, glomus cells exhibited voltage-dependent Na(+), Ca(2+) and K(+) currents that were qualitatively similar to those reported in lower mammals. These cells responded to hypoxia with an external Ca(2+)-dependent increase of cytosolic Ca(2+) and quantal catecholamine secretion, as reported for other mammalian species. Interestingly, human glomus cells are also responsive to hypoglycaemia and together these two stimuli can potentiate each other's effects. The chemosensory responses of glomus cells are also preserved at an advanced age. These new data on the cellular and molecular physiology of the CB pave the way for future pathophysiological studies involving this organ in humans.
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Affiliation(s)
- Patricia Ortega-Sáenz
- J. López-Barneo: Instituto de Biomedicina de Sevilla (IBiS), Campus Hospital Universitario Virgen del Rocío, Avenida Manuel Siurot s/n, 41013 Seville, Spain.
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Abstract
The discovery of the sensory nature of the carotid body dates back to the beginning of the 20th century. Following these seminal discoveries, research into carotid body mechanisms moved forward progressively through the 20th century, with many descriptions of the ultrastructure of the organ and stimulus-response measurements at the level of the whole organ. The later part of 20th century witnessed the first descriptions of the cellular responses and electrophysiology of isolated and cultured type I and type II cells, and there now exist a number of testable hypotheses of chemotransduction. The goal of this article is to provide a comprehensive review of current concepts on sensory transduction and transmission of the hypoxic stimulus at the carotid body with an emphasis on integrating cellular mechanisms with the whole organ responses and highlighting the gaps or discrepancies in our knowledge. It is increasingly evident that in addition to hypoxia, the carotid body responds to a wide variety of blood-borne stimuli, including reduced glucose and immune-related cytokines and we therefore also consider the evidence for a polymodal function of the carotid body and its implications. It is clear that the sensory function of the carotid body exhibits considerable plasticity in response to the chronic perturbations in environmental O2 that is associated with many physiological and pathological conditions. The mechanisms and consequences of carotid body plasticity in health and disease are discussed in the final sections of this article.
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Affiliation(s)
- Prem Kumar
- School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, The University of Birmingham, Birmingham, United Kingdom.
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Gallego-Martin T, Fernandez-Martinez S, Rigual R, Obeso A, Gonzalez C. Effects of low glucose on carotid body chemoreceptor cell activity studied in cultures of intact organs and in dissociated cells. Am J Physiol Cell Physiol 2011; 302:C1128-40. [PMID: 22189552 DOI: 10.1152/ajpcell.00196.2011] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The participation of the carotid body (CB) in glucose homeostasis and evidence obtained in simplified cultured CB slices or dissociated cells have led to the proposal that CB chemoreceptor cells are glucoreceptors. However, data generated in intact, freshly excised organs deny CB chemoreceptor cells' glucosensing properties. The physiological significance of the contention has prompted the present study, performed in a newly developed preparation of the intact CB organ in culture that maintains chemoreceptor cells' microenvironment. Chemoreceptor cells of intact CBs in culture retained their capacity to store, synthesize, and secrete catecholamine in response to hypoxia for at least 6 days. Aglycemia did not elicit neurosecretion in dissociated chemoreceptor cells or in intact CB in culture, but potentiated hypoxia-elicited neurosecretion, exclusively, in 1-day-old intact CB cultures and dissociated chemoreceptor cells cultured for 24 h. In fura 2-loaded cells, aglycemia (but not 1 mM) caused a slow Ca(2+)-dependent and nifedipine-insensitive increase in fluorescence at 340- to 380-nm wavelength emission ratio and augmented the fluorescent signal elicited by hypoxia. Association of nifedipine and KBR7943 (a Na(+)/Ca(2+) exchanger inhibitor) completely abolished the aglycemic Ca(2+) response. We conclude that chemoreceptor cells are not sensitive to hypoglycemia. We hypothesize that cultured chemoreceptor cells become transiently more dependent on glycolysis. Consequently, aglycemia would partially inhibit the Na(+)/K(+) pump, causing an increase in intracellular Na(+) concentration, and a reversal of Na(+)/Ca(2+) exchanger. This would slowly increase intracellular Ca(2+) concentration and cause the potentiation of the hypoxic responses. We discuss the nature of the signals detected by chemoreceptor cells for the CB to achieve its glycemic homeostatic role.
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Affiliation(s)
- Teresa Gallego-Martin
- Departamento de Bioquímica y Biología Molecular y Fisiología, Instituto de Biología y Genética Molecular y Centro de Investigación Biomédica en Red de Enfermedades Respiratorias, Universidad de Valladolid, Spain
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Wehrwein EA, Basu R, Basu A, Curry TB, Rizza RA, Joyner MJ. Hyperoxia blunts counterregulation during hypoglycaemia in humans: possible role for the carotid bodies? J Physiol 2010; 588:4593-601. [PMID: 20921201 DOI: 10.1113/jphysiol.2010.197491] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Chemoreceptors in the carotid bodies sense arterial oxygen tension and regulate respiration. Isolated carotid body glomus cells also sense glucose, and animal studies have shown the carotid bodies play a role in the counterregulatory response to hypoglycaemia. Thus, we hypothesized that glucose infusion rate would be augmented and neuro-hormonal counterregulation blunted during hypoglycaemia when the carotid bodies were desensitized by hyperoxia. Seven healthy adults (four male, three female) underwent two 180 min hyperinsulinaemic (2 mU (kg fat-free mass (FFM))(-1) min(-1)), hypoglycaemic (3.33 mmol l(-1)) clamps 1 week apart, randomized to either normoxia (arterial P(O2) (P(aO2)) 111 ± 6.3 mmHg) or hyperoxia (P(aO2) 345 ± 80.6 mmHg) (P < 0.05). Plasma glucose concentrations were similar during normoxia and hyperoxia at baseline (5.52 ± 0.15 vs. 5.55 ± 0.13 μmol ml(-1)) and during the clamp (3.4 ± 0.05 vs. 3.3 ± 0.05 μmol ml(-1)). The glucose infusion rate was 44.2 ± 3.5% higher (P < 0.01) during hyperoxia than normoxia at steady state during the clamp (28.2 ± 0.15 vs. 42.7 ± 0.65 μmol (kg FFM)(-1) min(-1); P < 0.01). Area under the curve values (expressed as percentage normoxia response) for counterregulatory hormones during hypoglycaemia were significantly suppressed by hyperoxia (noradrenaline 50.7 ± 5.2%, adrenaline 62.6 ± 3.3%, cortisol 63.2 ± 2.1%, growth hormone 53.1 ± 2.7%, glucagon 48.6 ± 2.1%, all P < 0.05 vs. normoxia). These data support the idea that the carotid bodies respond to glucose and play a role in the counterregulatory response to hypoglycaemia in humans.
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Affiliation(s)
- Erica A Wehrwein
- Department of Anesthesiology, Mayo Clinic, Rochester, MN 55905, USA
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Teppema LJ, Dahan A. The Ventilatory Response to Hypoxia in Mammals: Mechanisms, Measurement, and Analysis. Physiol Rev 2010; 90:675-754. [DOI: 10.1152/physrev.00012.2009] [Citation(s) in RCA: 257] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The respiratory response to hypoxia in mammals develops from an inhibition of breathing movements in utero into a sustained increase in ventilation in the adult. This ventilatory response to hypoxia (HVR) in mammals is the subject of this review. The period immediately after birth contains a critical time window in which environmental factors can cause long-term changes in the structural and functional properties of the respiratory system, resulting in an altered HVR phenotype. Both neonatal chronic and chronic intermittent hypoxia, but also chronic hyperoxia, can induce such plastic changes, the nature of which depends on the time pattern and duration of the exposure (acute or chronic, episodic or not, etc.). At adult age, exposure to chronic hypoxic paradigms induces adjustments in the HVR that seem reversible when the respiratory system is fully matured. These changes are orchestrated by transcription factors of which hypoxia-inducible factor 1 has been identified as the master regulator. We discuss the mechanisms underlying the HVR and its adaptations to chronic changes in ambient oxygen concentration, with emphasis on the carotid bodies that contain oxygen sensors and initiate the response, and on the contribution of central neurotransmitters and brain stem regions. We also briefly summarize the techniques used in small animals and in humans to measure the HVR and discuss the specific difficulties encountered in its measurement and analysis.
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Affiliation(s)
- Luc J. Teppema
- Department of Anesthesiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Albert Dahan
- Department of Anesthesiology, Leiden University Medical Center, Leiden, The Netherlands
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The Role of the Carotid Bodies in the Counter-Regulatory Response to Hypoglycemia. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2009; 648:273-80. [DOI: 10.1007/978-90-481-2259-2_31] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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Bibliography. Current world literature. Diabetes and the endocrine pancreas II. Curr Opin Endocrinol Diabetes Obes 2008; 15:383-93. [PMID: 18594281 DOI: 10.1097/med.0b013e32830c6b8e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Ward JPT. Oxygen sensors in context. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2007; 1777:1-14. [PMID: 18036551 DOI: 10.1016/j.bbabio.2007.10.010] [Citation(s) in RCA: 149] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 09/13/2007] [Revised: 10/21/2007] [Accepted: 10/24/2007] [Indexed: 01/02/2023]
Abstract
The ability to adapt to changes in the availability of O2 provides a critical advantage to all O2-dependent lifeforms. In mammals it allows optimal matching of the O2 requirements of the cells to ventilation and O2 delivery, underpins vital changes to the circulation during the transition from fetal to independent, air-breathing life, and provides a means by which dysfunction can be limited or prevented in disease. Certain tissues such as the carotid body, pulmonary circulation, neuroepithelial bodies and fetal adrenomedullary chromaffin cells are specialised for O2 sensing, though most others show for example alterations in transcription of specific genes during hypoxia. A number of mechanisms are known to respond to variations in PO2 over the physiological range, and have been proposed to fulfil the function as O2 sensors; these include modulation of mitochondrial oxidative phosphorylation and a number of O2-dependent synthetic and degradation pathways. There is however much debate as to their relative importance within and between specific tissues, whether their O2 sensitivity is actually appropriate to account for their proposed actions, and in particular their modus operandi. This review discusses our current understanding of how these mechanisms may operate, and attempts to put them into the context of the actual PO2 to which they are likely to be exposed. An important point raised is that the overall O2 sensitivity (P50) of any O2-dependent mechanism does not necessarily correlate with that of its O2 sensor, as the coupling function between the two may be complex and non-linear. In addition, although the bulk of the evidence suggests that mitochondria act as the key O2 sensor in carotid body, pulmonary artery and chromaffin cells, the signalling mechanisms by which alterations in their function are translated into a response appear to differ fundamentally, making a global unified theory of O2 sensing unlikely.
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Affiliation(s)
- Jeremy P T Ward
- King's College London School of Medicine, Division of Asthma, Allergy and Lung Biology, London SE1 9RT, UK
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Affiliation(s)
- Mark W J Strachan
- Metabolic Unit, Western General Hospital, Crewe Road, Edinburgh EH4 2XU, Scotland, UK.
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