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Gonzalez-Obeso E, Docio I, Olea E, Cogolludo A, Obeso A, Rocher A, Gomez-Niño A. Guinea Pig Oxygen-Sensing and Carotid Body Functional Properties. Front Physiol 2017; 8:285. [PMID: 28533756 PMCID: PMC5420588 DOI: 10.3389/fphys.2017.00285] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 04/19/2017] [Indexed: 01/06/2023] Open
Abstract
Mammals have developed different mechanisms to maintain oxygen supply to cells in response to hypoxia. One of those mechanisms, the carotid body (CB) chemoreceptors, is able to detect physiological hypoxia and generate homeostatic reflex responses, mainly ventilatory and cardiovascular. It has been reported that guinea pigs, originally from the Andes, have a reduced ventilatory response to hypoxia compared to other mammals, implying that CB are not completely functional, which has been related to genetically/epigenetically determined poor hypoxia-driven CB reflex. This study was performed to check the guinea pig CB response to hypoxia compared to the well-known rat hypoxic response. These experiments have explored ventilatory parameters breathing different gases mixtures, cardiovascular responses to acute hypoxia, in vitro CB response to hypoxia and other stimuli and isolated guinea pig chemoreceptor cells properties. Our findings show that guinea pigs are hypotensive and have lower arterial pO2 than rats, probably related to a low sympathetic tone and high hemoglobin affinity. Those characteristics could represent a higher tolerance to hypoxic environment than other rodents. We also find that although CB are hypo-functional not showing chronic hypoxia sensitization, a small percentage of isolated carotid body chemoreceptor cells contain tyrosine hydroxylase enzyme and voltage-dependent K+ currents and therefore can be depolarized. However hypoxia does not modify intracellular Ca2+ levels or catecholamine secretion. Guinea pigs are able to hyperventilate only in response to intense acute hypoxic stimulus, but hypercapnic response is similar to rats. Whether other brain areas are also activated by hypoxia in guinea pigs remains to be studied.
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Affiliation(s)
- Elvira Gonzalez-Obeso
- Servicio de Anatomía Patológica, Hospital Clínico Universitario de ValladolidValladolid, Spain
| | - Inmaculada Docio
- Departamento de Bioquímica y Biología Molecular y Fisiología, Universidad de Valladolid, IBGM, CSICValladolid, Spain.,CIBER de Enfermedades Respiratorias, ISCiiiSpain
| | - Elena Olea
- CIBER de Enfermedades Respiratorias, ISCiiiSpain.,Departamento de Enfermería, Universidad de Valladolid, IBGM, CSICValladolid, Spain
| | - Angel Cogolludo
- CIBER de Enfermedades Respiratorias, ISCiiiSpain.,Departamento de Farmacología, Instituto de Investigación Sanitaria Gregorio Marañón, Universidad Complutense de MadridMadrid, Spain
| | - Ana Obeso
- Departamento de Bioquímica y Biología Molecular y Fisiología, Universidad de Valladolid, IBGM, CSICValladolid, Spain.,CIBER de Enfermedades Respiratorias, ISCiiiSpain
| | - Asuncion Rocher
- Departamento de Bioquímica y Biología Molecular y Fisiología, Universidad de Valladolid, IBGM, CSICValladolid, Spain.,CIBER de Enfermedades Respiratorias, ISCiiiSpain
| | - Angela Gomez-Niño
- CIBER de Enfermedades Respiratorias, ISCiiiSpain.,Departamento de Biología Celular, Histología y Farmacología, Universidad de Valladolid, IBGM, CSICValladolid, Spain
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Zhou T, Chien MS, Kaleem S, Matsunami H. Single cell transcriptome analysis of mouse carotid body glomus cells. J Physiol 2016; 594:4225-51. [PMID: 26940531 DOI: 10.1113/jp271936] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2015] [Accepted: 02/24/2016] [Indexed: 01/12/2023] Open
Abstract
KEY POINTS Carotid body (CB) glomus cells mediate acute oxygen sensing and the initiation of the hypoxic ventilatory response, yet the gene expression profile of these cells is not available. We demonstrate that the single cell RNA-Seq method is a powerful tool for identifying highly expressed genes in CB glomus cells. Our single cell RNA-Seq results characterized novel CB glomus cell genes, including members of the G protein-coupled receptor signalling pathway, ion channels and atypical mitochondrial electron transport chain subunits. A heterologous cell-based screening identified acetate (which is known to affect CB glomus cell activity) as an agonist for the most highly abundant G protein-coupled receptor (Olfr78) in CB glomus cells. These data established the first transcriptome profile of CB glomus cells, highlighting genes with potential implications in CB chemosensory function. ABSTRACT The carotid body (CB) is a major arterial chemoreceptor containing glomus cells whose activities are regulated by changes in arterial blood content, including oxygen. Despite significant advancements in the characterization of their physiological properties, our understanding of the underlying molecular machinery and signalling pathway in CB glomus cells is still limited. To overcome this, we employed the single cell RNA-Seq method by performing next-generation sequencing on single glomus cell-derived cDNAs to eliminate contamination of genes derived from other cell types present in the CB. Using this method, we identified a set of genes abundantly expressed in glomus cells, which contained novel glomus cell-specific genes. Transcriptome and subsequent in situ hybridization and immunohistochemistry analyses identified abundant G protein-coupled receptor signalling pathway components and various types of ion channels, as well as members of the hypoxia-inducible factors pathway. A short-chain fatty acid olfactory receptor Olfr78, recently implicated in CB function, was the most abundant G protein-coupled receptor. Two atypical mitochondrial electron transport chain subunits (Ndufa4l2 and Cox4i2) were among the most specifically expressed genes in CB glomus cells, highlighting their potential roles in mitochondria-mediated oxygen sensing. The wealth of information provided by the present study offers a valuable foundation for identifying molecules functioning in the CB.
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Affiliation(s)
- Ting Zhou
- Department of Molecular Genetics and Microbiology, Duke University Medical Centre, Durham, NC, USA
| | - Ming-Shan Chien
- Department of Molecular Genetics and Microbiology, Duke University Medical Centre, Durham, NC, USA
| | - Safa Kaleem
- Department of Molecular Genetics and Microbiology, Duke University Medical Centre, Durham, NC, USA
| | - Hiroaki Matsunami
- Department of Molecular Genetics and Microbiology, Duke University Medical Centre, Durham, NC, USA.,Department of Neurobiology and Duke Institute for Brain Sciences, Duke University, Durham, NC, USA
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Prieto-Lloret J, Ramirez M, Olea E, Moral-Sanz J, Cogolludo A, Castañeda J, Yubero S, Agapito T, Gomez-Niño A, Rocher A, Rigual R, Obeso A, Perez-Vizcaino F, González C. Hypoxic pulmonary vasoconstriction, carotid body function and erythropoietin production in adult rats perinatally exposed to hyperoxia. J Physiol 2015; 593:2459-77. [PMID: 25833164 DOI: 10.1113/jp270274] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Accepted: 03/31/2015] [Indexed: 12/11/2022] Open
Abstract
KEY POINTS Adult animals that have been perinatally exposed to oxygen-rich atmospheres (hyperoxia), recalling those used for oxygen therapy in infants, exhibit a loss of hypoxic pulmonary vasoconstriction, whereas vasoconstriction elicited by depolarizing agents is maintained. Loss of pulmonary hypoxic vasoconstriction is not linked to alterations in oxygen-sensitive K(+) currents in pulmonary artery smooth muscle cells. Loss of hypoxic vasoconstriction is associated with early postnatal oxidative damage and corrected by an antioxidant diet. Perinatal hyperoxia damages carotid body chemoreceptor cell function and the antioxidant diet does not reverse it. The hypoxia-elicited increase in erythropoietin plasma levels is not affected by perinatal hyperoxia. The potential clinical significance of the findings in clinical situations such as pneumonia, chronic obstructive pulmonary disease or general anaesthesia is considered. ABSTRACT Adult mammalians possess three cell systems that are activated by acute bodily hypoxia: pulmonary artery smooth muscle cells (PASMC), carotid body chemoreceptor cells (CBCC) and erythropoietin (EPO)-producing cells. In rats, chronic perinatal hyperoxia causes permanent carotid body (CB) atrophy and functional alterations of surviving CBCC. There are no studies on PASMC or EPO-producing cells. Our aim is to define possible long-lasting functional changes in PASMC or EPO-producing cells (measured as EPO plasma levels) and, further, to analyse CBCC functional alterations. We used 3- to 4-month-old rats born and reared in a normal atmosphere or exposed to perinatal hyperoxia (55-60% O2 for the last 5-6 days of pregnancy and 4 weeks after birth). Perinatal hyperoxia causes an almost complete loss of hypoxic pulmonary vasoconstriction (HPV), which was correlated with lung oxidative status in early postnatal life and prevented by antioxidant supplementation in the diet. O2 -sensitivity of K(+) currents in the PASMC of hyperoxic animals is normal, indicating that their inhibition is not sufficient to trigger HPV. Perinatal hyperoxia also abrogated responses elicited by hypoxia on catecholamine and cAMP metabolism in the CB. An increase in EPO plasma levels elicited by hypoxia was identical in hyperoxic and control animals, implying a normal functioning of EPO-producing cells. The loss of HPV observed in adult rats and caused by perinatal hyperoxia, comparable to oxygen therapy in premature infants, might represent a previously unrecognized complication of such a medical intervention capable of aggravating medical conditions such as regional pneumonias, atelectases or general anaesthesia in adult life.
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Affiliation(s)
- Jesus Prieto-Lloret
- Departamento de Bioquímica y Biología Molecular y Fisiología/Instituto de Biología y Genética Molecular, Universidad de Valladolid/Consejo Superior de Investigaciones Científicas
| | - Maria Ramirez
- Departamento de Bioquímica y Biología Molecular y Fisiología/Instituto de Biología y Genética Molecular, Universidad de Valladolid/Consejo Superior de Investigaciones Científicas
| | - Elena Olea
- Departamento de Bioquímica y Biología Molecular y Fisiología/Instituto de Biología y Genética Molecular, Universidad de Valladolid/Consejo Superior de Investigaciones Científicas
| | - Javier Moral-Sanz
- Departamento de Farmacología, Facultad de Medicina, Universidad Complutense de Madrid, Instituto de Investigación Sanitaria Gregorio Marañón (IISGM), Facultad de Medicina, CIBER de Enfermedades Respiratorias/Instituto de Salud CIII, Valladolid, Spain
| | - Angel Cogolludo
- Departamento de Farmacología, Facultad de Medicina, Universidad Complutense de Madrid, Instituto de Investigación Sanitaria Gregorio Marañón (IISGM), Facultad de Medicina, CIBER de Enfermedades Respiratorias/Instituto de Salud CIII, Valladolid, Spain
| | - Javier Castañeda
- Departamento de Bioquímica y Biología Molecular y Fisiología/Instituto de Biología y Genética Molecular, Universidad de Valladolid/Consejo Superior de Investigaciones Científicas
| | - Sara Yubero
- Departamento de Bioquímica y Biología Molecular y Fisiología/Instituto de Biología y Genética Molecular, Universidad de Valladolid/Consejo Superior de Investigaciones Científicas
| | - Teresa Agapito
- Departamento de Bioquímica y Biología Molecular y Fisiología/Instituto de Biología y Genética Molecular, Universidad de Valladolid/Consejo Superior de Investigaciones Científicas
| | - Angela Gomez-Niño
- Departamento de Bioquímica y Biología Molecular y Fisiología/Instituto de Biología y Genética Molecular, Universidad de Valladolid/Consejo Superior de Investigaciones Científicas
| | - Asuncion Rocher
- Departamento de Bioquímica y Biología Molecular y Fisiología/Instituto de Biología y Genética Molecular, Universidad de Valladolid/Consejo Superior de Investigaciones Científicas
| | - Ricardo Rigual
- Departamento de Bioquímica y Biología Molecular y Fisiología/Instituto de Biología y Genética Molecular, Universidad de Valladolid/Consejo Superior de Investigaciones Científicas
| | - Ana Obeso
- Departamento de Bioquímica y Biología Molecular y Fisiología/Instituto de Biología y Genética Molecular, Universidad de Valladolid/Consejo Superior de Investigaciones Científicas
| | - Francisco Perez-Vizcaino
- Departamento de Farmacología, Facultad de Medicina, Universidad Complutense de Madrid, Instituto de Investigación Sanitaria Gregorio Marañón (IISGM), Facultad de Medicina, CIBER de Enfermedades Respiratorias/Instituto de Salud CIII, Valladolid, Spain
| | - Constancio González
- Departamento de Bioquímica y Biología Molecular y Fisiología/Instituto de Biología y Genética Molecular, Universidad de Valladolid/Consejo Superior de Investigaciones Científicas
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Nunes AR, Holmes AP, Conde SV, Gauda EB, Monteiro EC. Revisiting cAMP signaling in the carotid body. Front Physiol 2014; 5:406. [PMID: 25389406 PMCID: PMC4211388 DOI: 10.3389/fphys.2014.00406] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Accepted: 10/01/2014] [Indexed: 12/25/2022] Open
Abstract
Chronic carotid body (CB) activation is now recognized as being essential in the development of hypertension and promoting insulin resistance; thus, it is imperative to characterize the chemotransduction mechanisms of this organ in order to modulate its activity and improve patient outcomes. For several years, and although controversial, cyclic adenosine monophosphate (cAMP) was considered an important player in initiating the activation of the CB. However, its relevance was partially displaced in the 90s by the emerging role of the mitochondria and molecules such as AMP-activated protein kinase and O2-sensitive K+ channels. Neurotransmitters/neuromodulators binding to metabotropic receptors are essential to chemotransmission in the CB, and cAMP is central to this process. cAMP also contributes to raise intracellular Ca2+ levels, and is intimately related to the cellular energetic status (AMP/ATP ratio). Furthermore, cAMP signaling is a target of multiple current pharmacological agents used in clinical practice. This review (1) provides an outline on the classical view of the cAMP-signaling pathway in the CB that originally supported its role in the O2/CO2 sensing mechanism, (2) presents recent evidence on CB cAMP neuromodulation and (3) discusses how CB activity is affected by current clinical therapies that modify cAMP-signaling, namely dopaminergic drugs, caffeine (modulation of A2A/A2B receptors) and roflumilast (PDE4 inhibitors). cAMP is key to any process that involves metabotropic receptors and the intracellular pathways involved in CB disease states are likely to involve this classical second messenger. Research examining the potential modification of cAMP levels and/or interactions with molecules associated with CB hyperactivity is currently in its beginning and this review will open doors for future explorations.
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Affiliation(s)
- Ana R Nunes
- CEDOC, Chronic Diseases Research Center, NOVA Medical School/Faculdade de Ciências Médicas, Universidade Nova de Lisboa Lisboa, Portugal
| | - Andrew P Holmes
- School of Clinical and Experimental Medicine, University of Birmingham Birmingham, UK
| | - Sílvia V Conde
- CEDOC, Chronic Diseases Research Center, NOVA Medical School/Faculdade de Ciências Médicas, Universidade Nova de Lisboa Lisboa, Portugal
| | - Estelle B Gauda
- Neonatology Research Laboratories, Department of Pediatrics, Johns Hopkins Medical Institutions, Johns Hopkins University Baltimore, MD, USA
| | - Emília C Monteiro
- CEDOC, Chronic Diseases Research Center, NOVA Medical School/Faculdade de Ciências Médicas, Universidade Nova de Lisboa Lisboa, Portugal
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Tse A, Yan L, Lee AK, Tse FW. Autocrine and paracrine actions of ATP in rat carotid body. Can J Physiol Pharmacol 2012; 90:705-11. [PMID: 22509744 DOI: 10.1139/y2012-054] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Carotid bodies are peripheral chemoreceptors that detect lowering of arterial blood O(2) level. The carotid body comprises clusters of glomus (type I) cells surrounded by glial-like sustentacular (type II) cells. Hypoxia triggers depolarization and cytosolic [Ca(2+)] ([Ca(2+)](i)) elevation in glomus cells, resulting in the release of multiple transmitters, including ATP. While ATP has been shown to be an important excitatory transmitter in the stimulation of carotid sinus nerve, there is considerable evidence that ATP exerts autocrine and paracrine actions in carotid body. ATP acting via P2Y(1) receptors, causes hyperpolarization in glomus cells and inhibits the hypoxia-mediated [Ca(2+)](i) rise. In contrast, adenosine (an ATP metabolite) triggers depolarization and [Ca(2+)](i) rise in glomus cells via A(2A) receptors. We suggest that during prolonged hypoxia, the negative and positive feedback actions of ATP and adenosine may result in an oscillatory Ca(2+) signal in glomus cells. Such mechanisms may allow cyclic release of transmitters from glomus cells during prolonged hypoxia without causing cellular damage from a persistent [Ca(2+)](i) rise. ATP also stimulates intracellular Ca(2+) release in sustentacular cells via P2Y(2) receptors. The autocine and paracrine actions of ATP suggest that ATP has important roles in coordinating chemosensory transmission in the carotid body.
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Affiliation(s)
- Amy Tse
- Department of Pharmacology and Center for Neuroscience, 9-70 Medical Science Building, University of Alberta, Edmonton, AB T6G 2H7, Canada.
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6
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Monteiro TC, Batuca JR, Obeso A, González C, Monteiro EC. Carotid body function in aged rats: responses to hypoxia, ischemia, dopamine, and adenosine. AGE (DORDRECHT, NETHERLANDS) 2011; 33:337-350. [PMID: 20922488 PMCID: PMC3168591 DOI: 10.1007/s11357-010-9187-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2010] [Accepted: 09/14/2010] [Indexed: 05/29/2023]
Abstract
The carotid body (CB) is the main arterial chemoreceptor with a low threshold to hypoxia. CB activity is augmented by A(2)-adenosine receptors stimulation and attenuated by D(2)-dopamine receptors. The effect of aging on ventilatory responses mediated by the CB to hypoxia, ischemia, and to adenosine and dopamine administration is almost unknown. This study aims to investigate the ventilatory response to ischemia and to adenosine, dopamine, and their antagonists in old rats, as well as the effect of hypoxia on adenosine 3',5'-cyclic monophosphate (cAMP) accumulation in the aged CB. In vivo experiments were performed on young and aged rats anesthetized with pentobarbitone and breathing spontaneously. CB ischemia was induced by bilateral common carotid occlusions. cAMP content was measured in CB incubated with different oxygen concentrations. Hyperoxia caused a decrease in cAMP in the CB at all ages, but no differences were found between normoxia and hypoxia or between young and old animals. The endogenous dopaminergic inhibitory tonus is slightly reduced. However, both the ventilation decrease caused by exogenous dopamine and the increase mediated by A(2A)-adenosine receptors are not impaired in aged animals. The bradycardia induced by adenosine is attenuated in old rats. The CB's peripheral control of ventilation is preserved during aging. Concerns have also arisen regarding the clinical usage of adenosine to revert supraventricular tachycardia and the use of dopamine in critical care situations involving elderly people.
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Affiliation(s)
- Teresa Castro Monteiro
- Department of Pharmacology, CEDOC/Chronic Diseases Unit, Faculty of Medical Sciences, New University of Lisbon, Lisbon, Portugal.
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Rocher A, Caceres AI, Almaraz L, Gonzalez C. EPAC signalling pathways are involved in low PO2 chemoreception in carotid body chemoreceptor cells. J Physiol 2009; 587:4015-27. [PMID: 19581380 DOI: 10.1113/jphysiol.2009.172072] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Chemoreceptor cells of the carotid bodies (CB) are activated by hypoxia and acidosis, responding with an increase in their rate of neurotransmitter release, which in turn increases the electrical activity in the carotid sinus nerve and evokes a homeostatic hyperventilation. Studies in isolated chemoreceptor cells have shown that moderate hypoxias ( 46 mmHg) produces smaller depolarisations and comparable Ca(2+) transients but a much higher catecholamine (CA) release response in intact CBs than intense acidic/hypercapnic stimuli (20% CO(2), pH 6.6). Similarly, intense hypoxia ( 20 mmHg) produces smaller depolarizations and Ca(2+) transients in isolated chemoreceptor cells but a higher CA release response in intact CBs than a pure depolarizing stimulus (30-35 mm external K(+)). Studying the mechanisms responsible for these differences we have found the following. (1) Acidic hypercapnia inhibited I(Ca) (60%; whole cell) and CA release (45%; intact CB) elicited by ionomycin and high K(+). (2) Adenylate cyclase inhibition (SQ-22536; 80 microm) inhibited the hypoxic release response (>50%) and did not affect acidic/hypercapnic release, evidencing that the high gain of hypoxia to elicit neurotransmitter release is cAMP dependent. (3) The last effect was independent of PKA activation, as three kinase inhibitors (H-89, KT 5720 and Rp-cAMP; 10 x IC(50)) did not alter the hypoxic release response. (4) The Epac (exchange protein activated by cAMP) activator (8-pCPT-2-O-Me-cAMP, 100 microm) reversed the effects of the cyclase inhibitor. (5) The Epac inhibitor brefeldin A (100 microm) inhibited (54%) hypoxic induced release. Our findings show for the first time that an Epac-mediated pathway mediates O(2) sensing/transduction in chemoreceptor cells.
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Affiliation(s)
- Asuncion Rocher
- Departamento de Bioquímica y Biología Molecular y Fisiología, Facultad de Medicina-IBGM, Universidad de Valladolid - CSIC, C/Ramon y Cajal no. 7, 47005 Valladolid. Spain
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8
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He L, Dinger B, Sanders K, Hoidal J, Obeso A, Stensaas L, Fidone S, Gonzalez C. Effect of p47phoxgene deletion on ROS production and oxygen sensing in mouse carotid body chemoreceptor cells. Am J Physiol Lung Cell Mol Physiol 2005; 289:L916-24. [PMID: 16280459 DOI: 10.1152/ajplung.00015.2005] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Membrane potential in oxygen-sensitive type I cells in carotid body is controlled by diverse sets of voltage-dependent and -independent K+channels. Coupling of Po2to the open-closed state of channels may involve production of reactive oxygen species (ROS) by NADPH oxidase. One hypothesis suggests that ROS are produced in proportion to the prevailing Po2and a subset of K+channels closes as ROS levels decrease. We evaluated ROS levels in normal and p47phoxgene-deleted [NADPH oxidase knockout (KO)] type I cells using the ROS-sensitive dye dihydroethidium (DHE). In normal cells, hypoxia elicited an increase in ROS, which was blocked by the specific NADPH oxidase inhibitor 4-(2-aminoethyl)-benzenesulfonyl fluoride (AEBSF, 3 mM). KO type I cells did not respond to hypoxia, but the mitochondrial uncoupler azide (5 μM) elicited increased fluorescence in both normal and KO cells. Hypoxia had no effect on ROS production in sensory and sympathetic neurons. Methodological control experiments showed that stimulation of neutrophils with a cocktail containing the chemotactic peptide N-formyl-Met-Leu-Phe (1 μM), arachidonic acid (10 μM), and cytochalasin B (5 μg/ml) elicited a rapid increase in DHE fluorescence. This response was blocked by the NADPH oxidase inhibitor diphenyleneiodonium (10 μM). KO neutrophils did not respond; however, azide (5 μM) elicited a rapid increase in fluorescence. Physiological studies in type I cells demonstrated that hypoxia evoked an enhanced depression of K+current and increased intracellular Ca2+levels in KO vs. normal cells. Moreover, AEBSF potentiated hypoxia-induced increases in intracellular Ca2+and enhanced the depression of K+current in low O2. Our findings suggest that local compartmental increases in oxidase activity and ROS production inhibit the activity of type I cells by facilitating K+channel activity in hypoxia.
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Affiliation(s)
- L He
- Dept. of Physiology, University of Utah School of Medicine, 410 Chipeta Way, Salt Lake City, 84108 UT, USA
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Nikinmaa M. Oxygen-dependent cellular functions--why fishes and their aquatic environment are a prime choice of study. Comp Biochem Physiol A Mol Integr Physiol 2002; 133:1-16. [PMID: 12160868 DOI: 10.1016/s1095-6433(02)00132-0] [Citation(s) in RCA: 99] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Owing to the variability of oxygen tension in aquatic, especially the freshwater environment, oxygen has been a major force in the evolution of fishes. Their long evolutionary history, and the present different oxygen requirements between species, and acclimatory responses to hypoxic and hyperoxic conditions make fishes prime models in the study of oxygen-dependent cellular functions and their regulation. In the present article oxygen-dependent membrane transport, cellular signalling, energy metabolism, gene expression and apoptosis are reviewed with an emphasis on available results on fish. Available data on oxygen sensing are described and examples on the cascade from sensing oxygen to its physiological effects are given. From the data it is clear that hitherto fish have not been utilised in the study of oxygen-dependent cellular regulation as much as their evolutionary history and present oxygen requirements would give possibilities to. Even more generally, oxygen has hitherto seldom been a carefully controlled key variable in experimental cell biology.
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Affiliation(s)
- Mikko Nikinmaa
- Department of Biology, University of Turku, FIN-20014, Turku, Finland.
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Shkryl VM, Kostyuk PG, Lukyanetz EA. Dual action of cytosolic calcium on calcium channel activity during hypoxia in hippocampal neurones. Neuroreport 2001; 12:4035-9. [PMID: 11742234 DOI: 10.1097/00001756-200112210-00036] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The role of cytoplasmic calcium level (Ca(i)) in regulation of Ca channel activity during hypoxia was studied in hippocampal neurones from rats. Whole-cell patch clamp recordings in combination with measurements of O(2) partial pressure (pO(2)) were used. Lowering of pO(2) induced a potentiation of HVA Ca channel activity by 25.7% at Ca(i) = 75 nM in comparison with Ca(2+)-free solution. Increase of Ca(i) up to 410 nM slightly increased the effect and significantly slowed the Ca(2+) current run-down. On the other hand, hypoxia increased a steady-state channel inactivation and speeded up the kinetics of Ca(2+) current decay by about 30%. We conclude that moderate hypoxia induces dual action on Ca channels: intracellularly mediated augmentation of Ca influx via Ca channels and their Ca(2+)-dependent inactivation.
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Affiliation(s)
- V M Shkryl
- Department of General Physiology of Nervous System, Bogomoletz Institute of Physiology, Bogomoletz str. 4, Kiev 01024, Ukraine
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11
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Mironov SL, Richter DW. Hypoxic modulation of L-type Ca(2+) channels in inspiratory brainstem neurones: intracellular signalling pathways and metabotropic glutamate receptors. Brain Res 2000; 869:166-77. [PMID: 10865071 DOI: 10.1016/s0006-8993(00)02396-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Brief hypoxia (2 min) enhances the activity of L-type Ca(2+) (Ca(L)) channels. The effect is due to glutamate release and concomitant stimulation of metabotropic glutamate receptors of the mGLUR1/5 type [22] [S.L. Mironov, D.W. Richter, L-type Ca(2+) channels in inspiratory neurones and their modulation by hypoxia, J. Physiol. 512 (1998) 75-87.]. Besides increasing single channel activity, hypoxia induces a negative shift of the activation curve and slows down the inactivation of the Ca(L) current. In the present study we investigated these effects further, aiming to reveal intracellular signalling pathways that mediate the coupling between mGLURs and Ca(L) channels. Channel activity was recorded in cell-attached patches from inspiratory brainstem neurones of neonatal mice (P6-11). Ca(L) channels were inhibited by the mGluR2/3 agonists. mGluR1/5 agonists accelerated and mGluR2/3 agonists suppressed the respiratory output, and correspondingly modified the hypoxic response of the respiratory center. Ca(L) channels were also modulated by protein kinase C, but this did not prevent the hypoxic modification of channel activity. G-protein activators enhanced and G-protein inhibitors suppressed the Ca(L) channel activity, and in the presence of these agents the effects of hypoxia were abolished. Ryanodine but not thapsigargin inhibited the channel activity and occluded the hypoxic potentiation. Only G-protein-specific agents and ryanodine prevented the slowing down of inactivation induced by hypoxia. Our data indicate that coupling between mGluR1/5 and Ca(L) channels is mediated by pathways that utilize G-proteins and ryanodine receptors. Glutamate release and concomitant activation of Ca(L) channels are responsible for accelerating of respiratory rhythm during early hypoxia.
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Affiliation(s)
- S L Mironov
- II Department of Physiology, University of Göttingen, Humboldtallee 23, D-37073, Göttingen, Germany.
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Carpenter E, Peers C. Swelling- and cAMP-activated Cl- currents in isolated rat carotid body type I cells. J Physiol 1997; 503 ( Pt 3):497-511. [PMID: 9379407 PMCID: PMC1159837 DOI: 10.1111/j.1469-7793.1997.497bg.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
1. In the whole-cell configuration of the patch clamp technique, isolated rat carotid body type I cells exhibited reversible activation of Cl- currents during cell swelling effected by hypotonic extracellular solutions. 2. Hypotonic solutions evoked outwardly rectifying, non-inactivating currents which showed time-independent activation. The reversal potential (E(rev)) for the hypotonically evoked current was 1.6 +/- 0.6 mV (n = 26). Reduction of extracellular Cl- from 133 to 65.5 mM caused a shift in E(rev) of +14.7 +/- 0.4 mV (n = 5). 3. The swelling-activated Cl- current could not activate when ATP was omitted from the patch pipette or when substituted for the non-hydrolysable ATP analogues 5'-adenylylimidodiphosphate, AMP-PNP (2 mM) or beta, gamma-methylene-adenosine 5'-triphosphate. AMP-PCP (2 mM). The current also failed to activate in the absence of free intracellular Ca2+. 4. The swelling-activated Cl- current was sensitive to blockade by the Cl- channel blockers niflumic acid (300 microM) and 4,4'-diisothiocyanatostilbene-2, 2'-disulphonic acid (DIDS; 200 microM), although the blockade by DIDS was voltage dependent. 5. A similar, non-inactivating, outwardly rectifying Cl- current was evoked by the inclusion of cAMP (200 microM) in the patch pipette. This current could be inhibited by niflumic acid (300 microM), DIDS (200 microM) and hypertonic solutions, and was virtually abolished in the absence of intracellular ATP. 6. In conclusion, carotid body type I cells possess Cl- currents activated by cell swelling and rises in intracellular cAMP concentration. These currents may be involved in cell volume regulation, blood volume and osmolarity regulation and the response of the type I cell to chemostimuli.
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Affiliation(s)
- E Carpenter
- Institute for Cardiovascular Research, University of Leeds, UK.
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