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Sato T, Hanna P, Mori S. Innervation of the coronary arteries and its role in controlling microvascular resistance. J Cardiol 2024; 84:1-13. [PMID: 38346669 DOI: 10.1016/j.jjcc.2024.01.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Accepted: 01/30/2024] [Indexed: 04/08/2024]
Abstract
The coronary circulation plays a crucial role in balancing myocardial perfusion and oxygen demand to prevent myocardial ischemia. Extravascular compressive forces, coronary perfusion pressure, and microvascular resistance are involved to regulate coronary blood flow throughout the cardiac cycle. Autoregulation of the coronary blood flow through dynamic adjustment of microvascular resistance is maintained by complex interactions among mechanical, endothelial, metabolic, neural, and hormonal mechanisms. This review focuses on the neural mechanism. Anatomy and physiology of the coronary arterial innervation have been extensively investigated using animal models. However, findings in the animal heart have limited applicability to the human heart as cardiac innervation is generally highly variable among species. So far, limited data are available on the human coronary artery innervation, rendering multiple questions unresolved. Recently, the clinical entity of ischemia with non-obstructive coronary arteries has been proposed, characterized by microvascular dysfunction involving abnormal vasoconstriction and impaired vasodilation. Thus, measurement of microvascular resistance has become a standard diagnostic for patients without significant stenosis in the epicardial coronary arteries. Neural mechanism is likely to play a pivotal role, supported by the efficacy of cardiac sympathetic denervation to control symptoms in patients with angina. Therefore, understanding the coronary artery innervation and control of microvascular resistance of the human heart is increasingly important for cardiologists for diagnosis and to select appropriate therapeutic options. Advancement in this field can lead to innovations in diagnostic and therapeutic approaches for coronary artery diseases.
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Affiliation(s)
- Takanori Sato
- University of California Los Angeles (UCLA) Cardiac Arrhythmia Center, UCLA Health System, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Peter Hanna
- University of California Los Angeles (UCLA) Cardiac Arrhythmia Center, UCLA Health System, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Shumpei Mori
- University of California Los Angeles (UCLA) Cardiac Arrhythmia Center, UCLA Health System, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
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2
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Krasniqi X, Koçinaj D, Sejdiu B, Bashota L, Krasniqi A, Veliu F, Bakalli A. Large intercoronary communication between the right coronary artery and the left circumflex artery in a patient with late stent thrombosis: A case report. Radiol Case Rep 2023; 18:4585-4588. [PMID: 37916132 PMCID: PMC10615898 DOI: 10.1016/j.radcr.2023.09.076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2023] [Revised: 09/21/2023] [Accepted: 09/25/2023] [Indexed: 11/03/2023] Open
Abstract
Intercoronary communication (ICC) is a very rare coronary artery anomaly that connects directly 2 coronary arteries. This anastomosis is found between 2 nonobstructed coronary arteries with unidirectional or bidirectional blood flow. We report a case of a large ICC between the right coronary artery and the left circumflex artery in a patient with late stent thrombosis. The electrocardiogram showed ST-segment elevation in the anterior leads. The echocardiography investigation revealed hypokinesis in the proximal, medial and apical segments of the interventricular septum and anterior wall as well as the apex. During invasive coronary examination a large ICC between the left circumflex artery (LCx) and the right coronary artery (RCA) was found. Furthermore, coronary angiography demonstrated proximal occlusion (stent thrombosis) of the left anterior descending artery (LAD), prompting the utilization of percutaneous intervention with a drug-eluting stent. The presence of a large intercoronary communication is an exceedingly uncommon anomaly of the coronary arteries, which has the potential to induce myocardial ischemia. In individuals with obstructive coronary artery disease, this anomaly can further worsen the existing condition.
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Affiliation(s)
- Xhevdet Krasniqi
- Medical Faculty, University of Prishtina “Hasan Prishtina”, Pristina, Republic of Kosova
- Clinic of Cardiology, University Clinical Center of Kosova, Pristina, Republic of Kosova
| | | | - Basri Sejdiu
- Clinic of Cardiology, University Clinical Center of Kosova, Pristina, Republic of Kosova
| | - Lulzim Bashota
- Clinic of Cardiology, University Clinical Center of Kosova, Pristina, Republic of Kosova
| | - Agim Krasniqi
- Medical Faculty, University of Prishtina “Hasan Prishtina”, Pristina, Republic of Kosova
- Clinic of Cardiology, University Clinical Center of Kosova, Pristina, Republic of Kosova
| | - Fisnik Veliu
- Clinic of Cardiology, University Clinical Center of Kosova, Pristina, Republic of Kosova
| | - Aurora Bakalli
- Medical Faculty, University of Prishtina “Hasan Prishtina”, Pristina, Republic of Kosova
- Clinic of Cardiology, University Clinical Center of Kosova, Pristina, Republic of Kosova
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3
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Warne CM, Essajee SI, Tucker SM, Figueroa CA, Beard DA, Dick GM, Tune JD. Oxygen-sensing pathways below autoregulatory threshold act to sustain myocardial oxygen delivery during reductions in perfusion pressure. Basic Res Cardiol 2023; 118:12. [PMID: 36988670 PMCID: PMC10797605 DOI: 10.1007/s00395-023-00985-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 03/13/2023] [Accepted: 03/17/2023] [Indexed: 03/30/2023]
Abstract
The coronary circulation has an innate ability to maintain constant blood flow over a wide range of perfusion pressures. However, the mechanisms responsible for coronary autoregulation remain a fundamental and highly contested question. This study interrogated the local metabolic hypothesis of autoregulation by testing the hypothesis that hypoxemia-induced exaggeration of the metabolic error signal improves the autoregulatory response. Experiments were performed on open-chest anesthetized swine during stepwise changes in coronary perfusion pressure (CPP) from 140 to 40 mmHg under normoxic (n = 15) and hypoxemic (n = 8) conditions, in the absence and presence of dobutamine-induced increases in myocardial oxygen consumption (MVO2) (n = 5-7). Hypoxemia (PaO2 < 40 mmHg) decreased coronary venous PO2 (CvPO2) ~ 30% (P < 0.001) and increased coronary blood flow ~ 100% (P < 0.001), sufficient to maintain myocardial oxygen delivery (P = 0.14) over a wide range of CPPs. Autoregulatory responsiveness during hypoxemia-induced reductions in CvPO2 were associated with increases of autoregulatory gain (Gc; P = 0.033) but not slope (P = 0.585) over a CPP range of 120 to 60 mmHg. Preservation of autoregulatory Gc (P = 0.069) and slope (P = 0.264) was observed during dobutamine administration ± hypoxemia. Reductions in coronary resistance in response to decreases in CPP predominantly occurred below CvPO2 values of ~ 25 mmHg, irrespective of underlying vasomotor reserve. These findings support the presence of an autoregulatory threshold under which oxygen-sensing pathway(s) act to preserve sufficient myocardial oxygen delivery as CPP is reduced during increases in MVO2 and/or reductions in arterial oxygen content.
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Affiliation(s)
- Cooper M Warne
- Department of Physiology and Anatomy, University of North Texas Health Science Center, 3500 Camp Bowie Blvd., TX, 76107, Fort Worth, USA
| | - Salman I Essajee
- Department of Physiology and Anatomy, University of North Texas Health Science Center, 3500 Camp Bowie Blvd., TX, 76107, Fort Worth, USA
| | - Selina M Tucker
- Department of Physiology and Anatomy, University of North Texas Health Science Center, 3500 Camp Bowie Blvd., TX, 76107, Fort Worth, USA
| | - C Alberto Figueroa
- Section of Vascular Surgery, Department of Surgery, University of Michigan, Ann Arbor, USA
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, USA
| | - Daniel A Beard
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, USA
| | - Gregory M Dick
- Department of Physiology and Anatomy, University of North Texas Health Science Center, 3500 Camp Bowie Blvd., TX, 76107, Fort Worth, USA
| | - Johnathan D Tune
- Department of Physiology and Anatomy, University of North Texas Health Science Center, 3500 Camp Bowie Blvd., TX, 76107, Fort Worth, USA.
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4
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Hannemann J, Böger R. Dysregulation of the Nitric Oxide/Dimethylarginine Pathway in Hypoxic Pulmonary Vasoconstriction—Molecular Mechanisms and Clinical Significance. Front Med (Lausanne) 2022; 9:835481. [PMID: 35252268 PMCID: PMC8891573 DOI: 10.3389/fmed.2022.835481] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Accepted: 01/27/2022] [Indexed: 12/21/2022] Open
Abstract
The pulmonary circulation responds to hypoxia with vasoconstriction, a mechanism that helps to adapt to short-lived hypoxic episodes. When sustained, hypoxic pulmonary vasoconstriction (HPV) may become deleterious, causing right ventricular hypertrophy and failure, and contributing to morbidity and mortality in the late stages of several chronic pulmonary diseases. Nitric oxide (NO) is an important endothelial vasodilator. Its release is regulated, amongst other mechanisms, by the presence of endogenous inhibitors like asymmetric dimethylarginine (ADMA). Evidence has accumulated in recent years that elevated ADMA may be implicated in the pathogenesis of HPV and in its clinical sequelae, like pulmonary arterial hypertension (PAH). PAH is one phenotypic trait in experimental models with disrupted ADMA metabolism. In high altitude, elevation of ADMA occurs during long-term exposure to chronic or chronic intermittent hypobaric hypoxia; ADMA is significantly associated with high altitude pulmonary hypertension. High ADMA concentration was also reported in patients with chronic obstructive lung disease, obstructive sleep apnoea syndrome, and overlap syndrome, suggesting a pathophysiological role for ADMA-mediated impairment of endothelium-dependent, NO-mediated pulmonary vasodilation in these clinically relevant conditions. Improved understanding of the molecular (dys-)regulation of pathways controlling ADMA concentration may help to dissect the pathophysiology and find novel therapeutic options for these diseases.
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Affiliation(s)
- Juliane Hannemann
- Institute of Clinical Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- Institute DECIPHER, German-Chilean Institute for Research on Pulmonary Hypoxia and its Health Sequelae, Hamburg, Germany
| | - Rainer Böger
- Institute of Clinical Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- Institute DECIPHER, German-Chilean Institute for Research on Pulmonary Hypoxia and its Health Sequelae, Hamburg, Germany
- *Correspondence: Rainer Böger
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5
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Brandt MM, Cheng C, Merkus D, Duncker DJ, Sorop O. Mechanobiology of Microvascular Function and Structure in Health and Disease: Focus on the Coronary Circulation. Front Physiol 2022; 12:771960. [PMID: 35002759 PMCID: PMC8733629 DOI: 10.3389/fphys.2021.771960] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Accepted: 11/11/2021] [Indexed: 12/19/2022] Open
Abstract
The coronary microvasculature plays a key role in regulating the tight coupling between myocardial perfusion and myocardial oxygen demand across a wide range of cardiac activity. Short-term regulation of coronary blood flow in response to metabolic stimuli is achieved via adjustment of vascular diameter in different segments of the microvasculature in conjunction with mechanical forces eliciting myogenic and flow-mediated vasodilation. In contrast, chronic adjustments in flow regulation also involve microvascular structural modifications, termed remodeling. Vascular remodeling encompasses changes in microvascular diameter and/or density being largely modulated by mechanical forces acting on the endothelium and vascular smooth muscle cells. Whereas in recent years, substantial knowledge has been gathered regarding the molecular mechanisms controlling microvascular tone and how these are altered in various diseases, the structural adaptations in response to pathologic situations are less well understood. In this article, we review the factors involved in coronary microvascular functional and structural alterations in obstructive and non-obstructive coronary artery disease and the molecular mechanisms involved therein with a focus on mechanobiology. Cardiovascular risk factors including metabolic dysregulation, hypercholesterolemia, hypertension and aging have been shown to induce microvascular (endothelial) dysfunction and vascular remodeling. Additionally, alterations in biomechanical forces produced by a coronary artery stenosis are associated with microvascular functional and structural alterations. Future studies should be directed at further unraveling the mechanisms underlying the coronary microvascular functional and structural alterations in disease; a deeper understanding of these mechanisms is critical for the identification of potential new targets for the treatment of ischemic heart disease.
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Affiliation(s)
- Maarten M Brandt
- Division of Experimental Cardiology, Department of Cardiology, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - Caroline Cheng
- Division of Experimental Cardiology, Department of Cardiology, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands.,Division of Internal Medicine and Dermatology, Department of Nephrology and Hypertension, University Medical Center Utrecht, Utrecht, Netherlands
| | - Daphne Merkus
- Division of Experimental Cardiology, Department of Cardiology, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands.,Walter Brendel Center of Experimental Medicine (WBex), LMU Munich, Munich, Germany.,German Center for Cardiovascular Research (DZHK), Partner Site Munich, Munich Heart Alliance (MHA), Munich, Germany
| | - Dirk J Duncker
- Division of Experimental Cardiology, Department of Cardiology, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - Oana Sorop
- Division of Experimental Cardiology, Department of Cardiology, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands
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Silva YD, Munhoz L, Filho JRP, Damasceno AG, da Rosa CFF, Zukovski EB, Teng EZ, de Castro CC. Maxillary sinus volumetric changes in jet aircraft pilots: A multislice computed tomography pilot study. Imaging Sci Dent 2022; 53:53-60. [PMID: 37006792 PMCID: PMC10060761 DOI: 10.5624/isd.20220173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 11/03/2022] [Accepted: 11/16/2022] [Indexed: 12/14/2022] Open
Abstract
Purpose This study evaluated maxillary sinus volume changes in military jet aircraft pilot candidates before and after the training program, in comparison with a control group, considering the effects of pressurization, altitude, and total flight hours, through multislice computed tomography. Materials and Methods Fifteen fighter pilots were evaluated before initiating the training program and after the final approval. The control group consisted of 41 young adults who had not flown during their military career. The volumes of each maxillary sinus were measured individually before and at the end of the training program. Results When comparing the initial and final volumes in the pilots, a statistically significant increase was observed both in the left and right maxillary sinuses. When evaluating the average total volume of the maxillary sinuses (i.e., the average volume of the right and left maxillary sinuses together), a significant increase in the volume of the maxillary sinuses was observed in the pilot group when compared to the control group. Conclusion The maxillary sinus volumes in aircraft pilot candidates increased after the 8-month training program. This may be explained by changes in the gravitational force, the expansion of gas, and positive pressure from oxygen masks. This unprecedented investigation among pilots might lead to other investigations considering paranasal sinus alterations in this singular population.
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Affiliation(s)
- Yeda da Silva
- Institute of Radiology, School of Medicine, University of São Paulo, São Paulo, SP, Brazil
| | - Luciana Munhoz
- Department of Stomatology, School of Dentistry, University of São Paulo, São Paulo, SP, Brazil
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7
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Boulet LM, Atwater TL, Brown CV, Shafer BM, Vermeulen TD, Cotton PC, Day TA, Foster GE. Sex differences in the coronary vascular response to combined chemoreflex and metaboreflex stimulation in healthy humans. Exp Physiol 2021; 107:16-28. [PMID: 34788486 DOI: 10.1113/ep090034] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Accepted: 11/08/2021] [Indexed: 12/18/2022]
Abstract
NEW FINDINGS What is the central question of this study? Coronary blood flow in healthy humans is controlled by both local metabolic signalling and adrenergic activity: does the integration of these signals during acute hypoxia and adrenergic activation differ between sexes? What are the main findings and its importance? Both males and females exhibit an increase in coronary blood velocity in response to acute hypoxia, a response that is constrained by adrenergic stimulation in males but not females. These findings suggest that coronary blood flow control differs between males and females. ABSTRACT Coronary hyperaemia is mediated through multiple signalling pathways, including local metabolic messengers and adrenergic stimulation. This study aimed to determine whether the coronary vascular response to adrenergic stressors is different between sexes in normoxia and hypoxia. Young, healthy participants (n = 32; 16F) underwent three randomized trials of isometric handgrip exercise followed by post-exercise circulatory occlusion (PECO) to activate the muscle metaboreflex. End-tidal P O 2 was controlled at (1) normoxic levels throughout the trial, (2) 50 mmHg for the duration of the trial (hypoxia trial), or (3) 50 mmHg only during PECO (mixed trial). Mean left anterior descending coronary artery velocity (LADVmean ; transthoracic Doppler echocardiography), heart rate and blood pressure were assessed at baseline and during PECO. In normoxia, there was no change in LADVmean or cardiac workload induced by PECO in males and females. Acute hypoxia increased baseline LADVmean to a greater extent in males compared with females (P < 0.05), despite a similar increase in cardiac workload. The change in LADVmean induced by PECO was similar between sexes in normoxia (P = 0.31), greater in males during the mixed trial (male: 12.8 (7.7) cm/s vs. female: 8.1 (6.3) cm/s; P = 0.02) and reduced in males but not females in acute hypoxia (male: -4.8 (4.5) cm/s vs. female: 0.8 (6.2) cm/s; P = 0.006). In summary, sex differences in the coronary vasodilatory response to hypoxia were observed, and metaboreflex activation during hypoxia caused a paradoxical reduction in coronary blood velocity in males but not females.
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Affiliation(s)
- Lindsey M Boulet
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, British Columbia, Kelowna, Canada
| | - Taylor L Atwater
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, British Columbia, Kelowna, Canada
| | - Courtney V Brown
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, British Columbia, Kelowna, Canada
| | - Brooke M Shafer
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, British Columbia, Kelowna, Canada
| | - Tyler D Vermeulen
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, British Columbia, Kelowna, Canada
| | - Paul C Cotton
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, British Columbia, Kelowna, Canada
| | - Trevor A Day
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada
| | - Glen E Foster
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, British Columbia, Kelowna, Canada
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Sobh E, Reihan MS, Hifnawy TMS, Abdelsalam KG, Awad SS, Mahmoud NMH, Sindi NA, Alhadrami HA. Cardiovascular system and coronavirus disease-2019 (COVID-19): mutual injuries and unexpected outcomes. Egypt Heart J 2021; 73:77. [PMID: 34478001 PMCID: PMC8414463 DOI: 10.1186/s43044-021-00202-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Accepted: 08/18/2021] [Indexed: 02/10/2023] Open
Abstract
BACKGROUND Cardiovascular system involvement in coronavirus disease-2019 (COVID-19) has gained great interest in the scientific community. MAIN BODY Several studies reported increased morbidity and mortality among COVID-19 patients who had comorbidities, especially cardiovascular diseases like hypertension and acute coronary syndrome (ACS). COVID-19 may be associated with cardiovascular complications as arrhythmia, myocarditis, and thromboembolic events. We aimed to illustrate the interactions of COVID-19 disease and the cardiovascular system and the consequences on clinical decision as well as public health. CONCLUSIONS COVID-19 has negative consequences on the cardiovascular system. A high index of suspicion should be present to avoid poor prognosis of those presenting with unusual presentation.
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Affiliation(s)
- Eman Sobh
- Chest Diseases Department, Faculty of Medicine for Girls, Al-Azhar University, Cairo, Egypt.
- Respiratory Therapy Department, College of Medical Rehabilitation Sciences, Taibah University, Medina, Saudi Arabia.
| | - Muhammad Saad Reihan
- Cardiology Department, Faculty of Medicine, Al-Azhar University, Damietta, Egypt
- Alghad International College of Applied Medical Sciences, Jeddah, Saudi Arabia
| | - Tamer M S Hifnawy
- Public Health and Community Medicine Department, Faculty of Medicine, Beni-Suef University, Beni-Suef, Egypt
| | - Khloud Gamal Abdelsalam
- Biochemistry Unit, Chemistry Department, Faculty of Science, Damanhour University, Damanhour, Egypt
| | - Sohaila Sabry Awad
- Independent Researcher, Bachelor Degree of Biochemistry, Faculty of Science, Cairo University, Cairo, Egypt
| | | | - Nariman A Sindi
- Department of Medical Laboratory Technology, Faculty of Applied Medical Sciences, King Abdulaziz University, Jeddah, 21589, Saudi Arabia
| | - Hani A Alhadrami
- Department of Medical Laboratory Technology, Faculty of Applied Medical Sciences, King Abdulaziz University, Jeddah, 21589, Saudi Arabia
- Special Infectious Agent Unit, King Fahd Medical Research Centre, King Abdulaziz University, Jeddah, 21589, Saudi Arabia
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9
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Vontobel J. [Heart Patients and Exposure to Altitude]. PRAXIS 2021; 110:303-311. [PMID: 33906438 DOI: 10.1024/1661-8157/a003649] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Overall, heart patients should be advised individually with respect to their tolerance of altitudes. However, the historical reflex that altitude 'per se' is bad for heart patients should become a thing of the past. Adequately treated and stable patients can usually go up to an altitude of 2500 m without any restrictions. Higher altitudes are also possible for a large number of patients, but may require an adaptation of the medication and further clarification. This is especially the case when physical work is to be performed at great heights.
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10
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Coburn RF. Coronary and cerebral metabolism-blood flow coupling and pulmonary alveolar ventilation-blood flow coupling may be disabled during acute carbon monoxide poisoning. J Appl Physiol (1985) 2020; 129:1039-1050. [PMID: 32853110 DOI: 10.1152/japplphysiol.00172.2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Current evidence indicates that the toxicity of carbon monoxide (CO) poisoning results from increases in reactive oxygen species (ROS) generation plus tissue hypoxia resulting from decreases in capillary Po2 evoked by effects of increases in blood [carboxyhemoglobin] on the oxyhemoglobin dissociation curve. There has not been consideration of how increases in Pco could influence metabolism-blood flow coupling, a physiological mechanism that regulates the uniformity of tissue Po2, and alveolar ventilation-blood flow coupling, a mechanism that increases the efficiency of pulmonary O2 uptake. Using published data, I consider hypotheses that these coupling mechanisms, triggered by O2 and CO sensors located in arterial and arteriolar vessels in the coronary and cerebral circulations and in lung intralobar arteries, are disrupted during acute CO poisoning. These hypotheses are supported by calculations that show that the Pco in these vessels can reach levels during CO poisoning that would exert effects on signal transduction molecules involved in these coupling mechanisms.NEW & NOTEWORTHY This article introduces and supports a postulate that the tissue hypoxia component of carbon monoxide poisoning results in part from impairment of physiological adaptation mechanisms whereby tissues can match regional blood flow to O2 uptake, and the lung can match regional blood flow to alveolar ventilation.
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Affiliation(s)
- Ronald F Coburn
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
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11
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12
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Abstract
The heart is uniquely responsible for providing its own blood supply through the coronary circulation. Regulation of coronary blood flow is quite complex and, after over 100 years of dedicated research, is understood to be dictated through multiple mechanisms that include extravascular compressive forces (tissue pressure), coronary perfusion pressure, myogenic, local metabolic, endothelial as well as neural and hormonal influences. While each of these determinants can have profound influence over myocardial perfusion, largely through effects on end-effector ion channels, these mechanisms collectively modulate coronary vascular resistance and act to ensure that the myocardial requirements for oxygen and substrates are adequately provided by the coronary circulation. The purpose of this series of Comprehensive Physiology is to highlight current knowledge regarding the physiologic regulation of coronary blood flow, with emphasis on functional anatomy and the interplay between the physical and biological determinants of myocardial oxygen delivery. © 2017 American Physiological Society. Compr Physiol 7:321-382, 2017.
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Affiliation(s)
- Adam G Goodwill
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, IN
| | - Gregory M Dick
- California Medical Innovations Institute, 872 Towne Center Drive, Pomona, CA
| | - Alexander M Kiel
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, IN
- Weldon School of Biomedical Engineering, Purdue University, 206 S Martin Jischke Drive, Lafayette, IN
| | - Johnathan D Tune
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, IN
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13
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Boulet LM, Stembridge M, Tymko MM, Tremblay JC, Foster GE. The effects of graded changes in oxygen and carbon dioxide tension on coronary blood velocity independent of myocardial energy demand. Am J Physiol Heart Circ Physiol 2016; 311:H326-36. [PMID: 27233761 DOI: 10.1152/ajpheart.00107.2016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Accepted: 05/19/2016] [Indexed: 11/22/2022]
Abstract
In humans, coronary blood flow is tightly regulated by microvessels within the myocardium to match myocardial energy demand. However, evidence regarding inherent sensitivity of the microvessels to changes in arterial partial pressure of carbon dioxide and oxygen is conflicting because of the accompanied changes in myocardial energy requirements. This study aimed to investigate the changes in coronary blood velocity while manipulating partial pressures of end-tidal CO2 (Petco2) and O2 (Peto2). It was hypothesized that an increase in Petco2 (hypercapnia) or decrease in Peto2 (hypoxia) would result in a significant increase in mean blood velocity in the left anterior descending artery (LADVmean) due to an increase in both blood gases and energy demand associated with the concomitant cardiovascular response. Cardiac energy demand was assessed through noninvasive measurement of the total left ventricular mechanical energy. Healthy subjects (n = 13) underwent a euoxic CO2 test (Petco2 = -8, -4, 0, +4, and +8 mmHg from baseline) and an isocapnic hypoxia test (Peto2 = 64, 52, and 45 mmHg). LADVmean was assessed using transthoracic Doppler echocardiography. Hypercapnia evoked a 34.6 ± 8.5% (mean ± SE; P < 0.01) increase in mean LADVmean, whereas hypoxia increased LADVmean by 51.4 ± 8.8% (P < 0.05). Multiple stepwise regressions revealed that both mechanical energy and changes in arterial blood gases are important contributors to the observed changes in LADVmean (P < 0.01). In summary, regulation of the coronary vasculature in humans is mediated by metabolic changes within the heart and an inherent sensitivity to arterial blood gases.
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Affiliation(s)
- Lindsey M Boulet
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, Canada; and
| | - Mike Stembridge
- Cardiff School of Sport, Cardiff Metropolitan University, Cardiff, United Kingdom
| | - Michael M Tymko
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, Canada; and
| | - Joshua C Tremblay
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, Canada; and
| | - Glen E Foster
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, Canada; and
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14
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Haick JM, Byron KL. Novel treatment strategies for smooth muscle disorders: Targeting Kv7 potassium channels. Pharmacol Ther 2016; 165:14-25. [PMID: 27179745 DOI: 10.1016/j.pharmthera.2016.05.002] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Smooth muscle cells provide crucial contractile functions in visceral, vascular, and lung tissues. The contractile state of smooth muscle is largely determined by their electrical excitability, which is in turn influenced by the activity of potassium channels. The activity of potassium channels sustains smooth muscle cell membrane hyperpolarization, reducing cellular excitability and thereby promoting smooth muscle relaxation. Research over the past decade has indicated an important role for Kv7 (KCNQ) voltage-gated potassium channels in the regulation of the excitability of smooth muscle cells. Expression of multiple Kv7 channel subtypes has been demonstrated in smooth muscle cells from viscera (gastrointestinal, bladder, myometrial), from the systemic and pulmonary vasculature, and from the airways of the lung, from multiple species, including humans. A number of clinically used drugs, some of which were developed to target Kv7 channels in other tissues, have been found to exert robust effects on smooth muscle Kv7 channels. Functional studies have indicated that Kv7 channel activators and inhibitors have the ability to relax and contact smooth muscle preparations, respectively, suggesting a wide range of novel applications for the pharmacological tool set. This review summarizes recent findings regarding the physiological functions of Kv7 channels in smooth muscle, and highlights potential therapeutic applications based on pharmacological targeting of smooth muscle Kv7 channels throughout the body.
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Affiliation(s)
- Jennifer M Haick
- Department of Molecular Pharmacology & Therapeutics, Stritch School of Medicine, Loyola University Chicago, Maywood, IL, USA
| | - Kenneth L Byron
- Department of Molecular Pharmacology & Therapeutics, Stritch School of Medicine, Loyola University Chicago, Maywood, IL, USA.
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15
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Abstract
Nitric oxide (NO) generated by endothelial cells to relax vascular smooth muscle is one of the most intensely studied molecules in the past 25 years. Much of what is known about NO regulation of NO is based on blockade of its generation and analysis of changes in vascular regulation. This approach has been useful to demonstrate the importance of NO in large scale forms of regulation but provides less information on the nuances of NO regulation. However, there is a growing body of studies on multiple types of in vivo measurement of NO in normal and pathological conditions. This discussion will focus on in vivo studies and how they are reshaping the understanding of NO's role in vascular resistance regulation and the pathologies of hypertension and diabetes mellitus. The role of microelectrode measurements in the measurement of [NO] will be considered because much of the controversy about what NO does and at what concentration depends upon the measurement methodology. For those studies where the technology has been tested and found to be well founded, the concept evolving is that the stresses imposed on the vasculature in the form of flow-mediated stimulation, chemicals within the tissue, and oxygen tension can cause rapid and large changes in the NO concentration to affect vascular regulation. All these functions are compromised in both animal and human forms of hypertension and diabetes mellitus due to altered regulation of endothelial cells and formation of oxidants that both damage endothelial cells and change the regulation of endothelial nitric oxide synthase.
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Affiliation(s)
- Harold Glenn Bohlen
- Department of Cellular and Integrative Physiology, Indiana University Medical School, Indianapolis, Indiana, Indiana, USA
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Heinonen IHA, Boushel R, Kalliokoski KK. The Circulatory and Metabolic Responses to Hypoxia in Humans - With Special Reference to Adipose Tissue Physiology and Obesity. Front Endocrinol (Lausanne) 2016; 7:116. [PMID: 27621722 PMCID: PMC5002918 DOI: 10.3389/fendo.2016.00116] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Accepted: 08/10/2016] [Indexed: 01/07/2023] Open
Abstract
Adipose tissue metabolism and circulation play an important role in human health. It is well-known that adipose tissue mass is increased in response to excess caloric intake leading to obesity and further to local hypoxia and inflammatory signaling. Acute exercise increases blood supply to adipose tissue and mobilization of fat stores for energy. However, acute exercise during systemic hypoxia reduces subcutaneous blood flow in healthy young subjects, but the response in overweight or obese subjects remains to be investigated. Emerging evidence also indicates that exercise training during hypoxic exposure may provide additive benefits with respect to many traditional cardiovascular risk factors as compared to exercise performed in normoxia, but unfavorable effects of hypoxia have also been documented. These topics will be covered in this brief review dealing with hypoxia and adipose tissue physiology.
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Affiliation(s)
- Ilkka H. A. Heinonen
- Turku PET Centre, University of Turku, Turku, Finland
- Department of Clinical Physiology and Nuclear Medicine, University of Turku, Turku, Finland
- Division of Experimental Cardiology, Thoraxcenter, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands
- *Correspondence: Ilkka H. A. Heinonen,
| | - Robert Boushel
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
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Rimoldi SF, Rexhaj E, Villena M, Salmon CS, Allemann Y, Scherrer U, Sartori C. Novel Insights into Cardiovascular Regulation in Patients with Chronic Mountain Sickness. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 903:83-100. [PMID: 27343090 DOI: 10.1007/978-1-4899-7678-9_6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Studies of high-altitude populations, and in particular of maladapted subgroups, may provide important insight into underlying mechanisms involved in the pathogenesis of hypoxemia-related disease in general. Chronic mountain sickness (CMS) is a major public health problem in mountainous regions of the world affecting many millions of high-altitude dwellers. It is characterized by exaggerated chronic hypoxemia, erythrocytosis, and mild pulmonary hypertension. In later stages these patients often present with right heart failure and are predisposed to systemic cardiovascular disease, but the underlying mechanisms are poorly understood. Here, we present recent new data providing insight into underlying mechanisms that may cause these complications.
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Affiliation(s)
- Stefano F Rimoldi
- Department of Cardiology, Swiss Cardiovascular Center Bern, University Hospital, Bern, Switzerland.
- Department of Internal Medicine, Botnar Center for Extreme Medicine, University Hospital, Lausanne, CHUV, Switzerland.
| | - Emrush Rexhaj
- Department of Cardiology, Swiss Cardiovascular Center Bern, University Hospital, Bern, Switzerland
- Department of Internal Medicine, Botnar Center for Extreme Medicine, University Hospital, Lausanne, CHUV, Switzerland
| | | | | | - Yves Allemann
- Department of Cardiology, Swiss Cardiovascular Center Bern, University Hospital, Bern, Switzerland
| | - Urs Scherrer
- Department of Cardiology, Swiss Cardiovascular Center Bern, University Hospital, Bern, Switzerland
- Department of Internal Medicine, Botnar Center for Extreme Medicine, University Hospital, Lausanne, CHUV, Switzerland
- Departamento de Biología, Facultad de Ciencias, Universidad de Tarapacá, Arica, Chile
| | - Claudio Sartori
- Department of Internal Medicine, Botnar Center for Extreme Medicine, University Hospital, Lausanne, CHUV, Switzerland
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Bone DBJ, Antic M, Quinonez D, Hammond JR. Hypoxanthine uptake by skeletal muscle microvascular endothelial cells from equilibrative nucleoside transporter 1 (ENT1)-null mice: effect of oxidative stress. Microvasc Res 2014; 98:16-22. [PMID: 25448155 DOI: 10.1016/j.mvr.2014.11.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Revised: 11/13/2014] [Accepted: 11/17/2014] [Indexed: 12/31/2022]
Abstract
Adenosine is an endogenous regulator of vascular tone. This activity of adenosine is terminated by its uptake and metabolism by microvascular endothelial cells (MVEC). The predominant transporter involved is ENT1 (equilibrative nucleoside transporter subtype 1). MVEC also express the nucleobase transporter (ENBT1) which is involved in the cellular flux of adenosine metabolites such as hypoxanthine. Changes in either of these transport systems would impact the bioactivity of adenosine and its metabolism, including the formation of oxygen free radicals. MVEC isolated from skeletal muscle of ENT1(+/+) and ENT1(-/-) mice were subjected to oxidative stress induced by simulated ischemia/reperfusion or menadione. The functional activities of ENT1 and ENBT1 were assessed based on zero-trans influx kinetics of radiolabeled substrates. There was a reduction in the rate of ENBT1-mediated hypoxanthine uptake by ENT1(+/+) MVEC treated with menadione or after exposure to conditions that simulate ischemia/reperfusion. In both cases, the superoxide dismutase mimetic MnTMPyP attenuated the loss of ENBT1 activity, implicating superoxide radicals in the response. In contrast, MVEC isolated from ENT1(-/-) mice showed no reduction in ENBT1 activity upon treatment with menadione or simulated ischemia/reperfusion, but they did have a significantly higher level of catalase activity relative to ENT1(+/+) MVEC. These data suggest that ENBT1 activity is decreased in MVEC in response to the increased superoxide radical that is associated with ischemia/reperfusion injury. MVEC isolated from ENT1(-/-) mice do not show this reduction in ENBT1, possibly due to increased catalase activity.
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Affiliation(s)
- D B J Bone
- Department of Physiology and Pharmacology, Western University, London, Ontario N6A 5C1, Canada.
| | - M Antic
- Department of Physiology and Pharmacology, Western University, London, Ontario N6A 5C1, Canada
| | - D Quinonez
- Department of Physiology and Pharmacology, Western University, London, Ontario N6A 5C1, Canada.
| | - J R Hammond
- Department of Physiology and Pharmacology, Western University, London, Ontario N6A 5C1, Canada.
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Bone DB, Antic M, Vilas G, Hammond JR. Oxidative stress modulates nucleobase transport in microvascular endothelial cells. Microvasc Res 2014; 95:68-75. [DOI: 10.1016/j.mvr.2014.06.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Revised: 06/07/2014] [Accepted: 06/10/2014] [Indexed: 12/23/2022]
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21
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Soukoulis V, Boden WE, Smith SC, O'Gara PT. Nonantithrombotic medical options in acute coronary syndromes: old agents and new lines on the horizon. Circ Res 2014; 114:1944-58. [PMID: 24902977 PMCID: PMC4083844 DOI: 10.1161/circresaha.114.302804] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Acute coronary syndromes (ACS) constitute a spectrum of clinical presentations ranging from unstable angina and non-ST-segment elevation myocardial infarction to ST-segment myocardial infarction. Myocardial ischemia in this context occurs as a result of an abrupt decrease in coronary blood flow and resultant imbalance in the myocardial oxygen supply-demand relationship. Coronary blood flow is further compromised by other mechanisms that increase coronary vascular resistance or reduce coronary driving pressure. The goals of treatment are to decrease myocardial oxygen demand, increase coronary blood flow and oxygen supply, and limit myocardial injury. Treatments are generally divided into disease-modifying agents or interventions that improve hard clinical outcomes and other strategies that can reduce ischemia. In addition to traditional drugs such as β-blockers and inhibitors of the renin-angiotensin-aldosterone system, newer agents have expanded the number of molecular pathways targeted for treatment of ACS. Ranolazine, trimetazidine, nicorandil, and ivabradine are medications that have been shown to reduce myocardial ischemia through diverse mechanisms and have been tested in limited fashion in patients with ACS. Attenuating the no-reflow phenomenon and reducing the injury compounded by acute reperfusion after a period of coronary occlusion are active areas of research. Additionally, interventions aimed at ischemic pre- and postconditioning may be useful means by which to limit myocardial infarct size. Trials are also underway to examine altered metabolic and oxygen-related pathways in ACS. This review will discuss traditional and newer anti-ischemic therapies for patients with ACS, exclusive of revascularization, antithrombotic agents, and the use of high-intensity statins.
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Affiliation(s)
- Victor Soukoulis
- From the Cardiovascular Division, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA (V.S., P.T.O.); Division of Cardiology, Department of Medicine, Albany Stratton Veteran's Affairs Medical Centre and Albany Medical College, NY (W.E.B.); and Division of Cardiology, University of North Carolina, Chapel Hill (S.C.S.)
| | - William E Boden
- From the Cardiovascular Division, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA (V.S., P.T.O.); Division of Cardiology, Department of Medicine, Albany Stratton Veteran's Affairs Medical Centre and Albany Medical College, NY (W.E.B.); and Division of Cardiology, University of North Carolina, Chapel Hill (S.C.S.)
| | - Sidney C Smith
- From the Cardiovascular Division, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA (V.S., P.T.O.); Division of Cardiology, Department of Medicine, Albany Stratton Veteran's Affairs Medical Centre and Albany Medical College, NY (W.E.B.); and Division of Cardiology, University of North Carolina, Chapel Hill (S.C.S.)
| | - Patrick T O'Gara
- From the Cardiovascular Division, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA (V.S., P.T.O.); Division of Cardiology, Department of Medicine, Albany Stratton Veteran's Affairs Medical Centre and Albany Medical College, NY (W.E.B.); and Division of Cardiology, University of North Carolina, Chapel Hill (S.C.S.).
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22
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Hedegaard ER, Nielsen BD, Mogensen S, Rembold CM, Frøbert O, Simonsen U. Mechanisms involved in increased sensitivity to adenosine A(2A) receptor activation and hypoxia-induced vasodilatation in porcine coronary arteries. Eur J Pharmacol 2013; 723:216-26. [PMID: 24309216 DOI: 10.1016/j.ejphar.2013.11.029] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Revised: 11/18/2013] [Accepted: 11/23/2013] [Indexed: 01/11/2023]
Abstract
Hypoxia-induced coronary vasorelaxation is a compensatory mechanism increasing blood flow. We hypothesized that hypoxia shares pathways with adenosine and causes vasorelaxation through the adenosine A(2A) receptor and force suppression by increasing cAMP and phosphorylated heat shock protein (HSP)20. Adenosine receptors in porcine left anterior descending coronary arteries (LAD) were examined by RT-PCR and isometric tension recording in myographs. Vasorelaxation was induced by adenosine, 1% oxygen, or both in the absence or presence of ZM241385, an adenosine A(2A) receptor antagonist. cAMP was determined by ELISA and p-HSP20/HSP20 and p-MLC/MLC were determined by immunoblotting and densitometric analyses. In coronary arteries exposed to 1% oxygen, there was increased sensitivity to adenosine, the adenosine A2 selective agonist NECA, and the adenosine A(2A) selective receptor agonist CGS21680. ZM241385 shifted concentration-response curves for CGS21680 to the right, whereas the adenosine A1 antagonist DPCPX, the adenosine A2B receptor antagonist MRS1754 and the adenosine A3 receptor antagonist MRS1523 failed to reduce vasodilatation induced by CGS21680. 1% oxygen or adenosine increased cAMP accumulation and HSP20 phosphorylation without changing T850-MYPT1 and MLC phosphorylation. ZM241385 failed to change 1% oxygen-induced vasodilation, cAMP accumulation, HSP20 phosphorylation and MLC phosphorylation. The PKA inhibitor Rp-8-CPT-cAMPS significantly reduced vasorelaxation induced by 1% oxygen or CGS21680. Our findings suggest that the increased sensitivity to adenosine, NECA, and CGS21680 at 1% oxygen involves adenosine A(2A) receptors. Adenosine and 1% oxygen induce vasorelaxation in PGF2α-contracted porcine coronary arteries partly by force suppression caused by increased cAMP and phosphorylation of HSP20.
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Affiliation(s)
- Elise R Hedegaard
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, MEMBRANES, University of Aarhus, Denmark.
| | - Berit D Nielsen
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, MEMBRANES, University of Aarhus, Denmark; Department of Rheumatology, Aarhus University Hospital, Denmark
| | - Susie Mogensen
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, MEMBRANES, University of Aarhus, Denmark
| | - Christopher M Rembold
- Cardiovascular Division, Department of Internal Medicine, University of Virginia Health System, Charlottesville, VA, USA
| | - Ole Frøbert
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, MEMBRANES, University of Aarhus, Denmark; Department of Cardiology, Örebro University Hospital, Sweden
| | - Ulf Simonsen
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, MEMBRANES, University of Aarhus, Denmark
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Wozniak CJ, Baird BC, Stehlik J, Drakos SG, Bull DA, Patel AN, Selzman CH. Improved survival in heart transplant patients living at high altitude. J Thorac Cardiovasc Surg 2011; 143:735-741.e1. [PMID: 22169457 DOI: 10.1016/j.jtcvs.2011.11.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2011] [Revised: 10/03/2011] [Accepted: 11/08/2011] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Higher altitudes are associated with chronic hypoxia and elevated pulmonary vascular resistance, both potentially detrimental to patients requiring heart transplantation. The purpose of the present study was to determine whether altitude negatively affects survival among patients undergoing heart transplantation. METHODS The United Network of Organ Sharing database for adult patients undergoing heart transplantation from 1990 to 2008 (n = 36,529) was analyzed, and each patient was assigned an altitude according to their home ZIP code. Survival was compared between patients at less than 2000 ft, 2000 or more to less than 4000 ft, and 4000 ft or more. Adjusted survival was calculated using Cox proportional hazards analysis with propensity-matched stratification. RESULTS Patients living at above 2000 ft had a 16% reduction in the risk of death at 1 year after transplant (P = .006) compared with those at lower altitudes. At 5 and 10 years, the risk reduction was 6% (P = .21) and 6% (P = .114), respectively. Among patients living above 4000 ft, the 1-, 5-, and 10-year reduction in the risk of death was 20% (P = .022), 12% (P = .057), and 15% (P = .0052) compared with those living below 2000 ft, respectively. Patients at high altitude had a lower incidence of diabetes, used tobacco less often, and accounted for the greatest proportion of status 2 heart transplants. Comparing the factors predicting survival at high and low altitudes, patients with a status 1A listing had improved outcomes at higher altitudes. CONCLUSIONS Patients living above 2000 ft have improved survival after heart transplantation, an advantage even more pronounced at 4000 ft. Although the mechanism of protection remains unclear, the findings might reflect differences in pre-2006 organ allocation.
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Affiliation(s)
- Curtis J Wozniak
- Division of Cardiothoracic Surgery, University of Utah, Salt Lake City, UT 84132-2101, USA
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Koos BJ. Adenosine A₂a receptors and O₂ sensing in development. Am J Physiol Regul Integr Comp Physiol 2011; 301:R601-22. [PMID: 21677265 DOI: 10.1152/ajpregu.00664.2010] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Reduced mitochondrial oxidative phosphorylation, via activation of adenylate kinase and the resulting exponential rise in the cellular AMP/ATP ratio, appears to be a critical factor underlying O₂ sensing in many chemoreceptive tissues in mammals. The elevated AMP/ATP ratio, in turn, activates key enzymes that are involved in physiologic adjustments that tend to balance ATP supply and demand. An example is the conversion of AMP to adenosine via 5'-nucleotidase and the resulting activation of adenosine A(₂A) receptors, which are involved in acute oxygen sensing by both carotid bodies and the brain. In fetal sheep, A(₂A) receptors associated with carotid bodies trigger hypoxic cardiovascular chemoreflexes, while central A(₂A) receptors mediate hypoxic inhibition of breathing and rapid eye movements. A(₂A) receptors are also involved in hypoxic regulation of fetal endocrine systems, metabolism, and vascular tone. In developing lambs, A(₂A) receptors play virtually no role in O₂ sensing by the carotid bodies, but brain A(₂A) receptors remain critically involved in the roll-off ventilatory response to hypoxia. In adult mammals, A(₂A) receptors have been implicated in O₂ sensing by carotid glomus cells, while central A(₂A) receptors likely blunt hypoxic hyperventilation. In conclusion, A(₂A) receptors are crucially involved in the transduction mechanisms of O₂ sensing in fetal carotid bodies and brains. Postnatally, central A(₂A) receptors remain key mediators of hypoxic respiratory depression, but they are less critical for O₂ sensing in carotid chemoreceptors, particularly in developing lambs.
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Affiliation(s)
- Brian J Koos
- Department of Obstetrics and Gynecology; Brain Research Institute, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, California, USA.
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Hedegaard ER, Stankevicius E, Simonsen U, Fröbert O. Non-endothelial endothelin counteracts hypoxic vasodilation in porcine large coronary arteries. BMC PHYSIOLOGY 2011; 11:8. [PMID: 21575165 PMCID: PMC3118136 DOI: 10.1186/1472-6793-11-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/10/2010] [Accepted: 05/15/2011] [Indexed: 11/25/2022]
Abstract
Background The systemic vascular response to hypoxia is vasodilation. However, reports suggest that the potent vasoconstrictor endothelin-1 (ET-1) is released from the vasculature during hypoxia. ET-1 is reported to augment superoxide anion generation and may counteract nitric oxide (NO) vasodilation. Moreover, ET-1 was proposed to contribute to increased vascular resistance in heart failure by increasing the production of asymmetric dimethylarginine (ADMA). We investigated the role of ET-1, the NO pathway, the potassium channels and radical oxygen species in hypoxia-induced vasodilation of large coronary arteries. Results In prostaglandin F2α (PGF2α, 10 μM)-contracted segments with endothelium, gradual lowering of oxygen tension from 95 to 1% O2 resulted in vasodilation. The vasodilation to O2 lowering was rightward shifted in segments without endothelium at all O2 concentrations except at 1% O2. The endothelin receptor antagonist SB217242 (10 μM) markedly increased hypoxic dilation despite the free tissue ET-1 concentration in the arterial wall was unchanged in 1% O2 versus 95% O2. Exogenous ET-1 reversed hypoxic dilation in segments with and without endothelium, and the hypoxic arteries showed an increased sensitivity towards ET-1 compared to the normoxic controls. Without affecting basal NO, hypoxia increased NO concentration in PGF2α-contracted arteries, and an NO synthase inhibitor, L-NOARG,(300 μM, NG-nitro-L-Arginine) reduced hypoxic vasodilation. NO-induced vasodilation was reduced in endothelin-contracted preparations. Arterial wall ADMA concentrations were unchanged by hypoxia. Blocking of potassium channels with TEA (tetraethylammounium chloride)(10 μM) inhibited vasodilation to O2 lowering as well as to NO. The superoxide scavenger tiron (10 μM) and the putative NADPH oxidase inhibitor apocynin (10 μM) leftward shifted concentration-response curves for O2 lowering without changing vasodilation to 1% O2. PEG (polyethylene glycol) catalase (300 u/ml) inhibited H2O2 vasodilation, but failed to affect vasodilation to O2 lowering. Neither did PEG-SOD (polyethylene glycol superoxide dismutase)(70 u/ml) affect vasodilation to O2 lowering. The mitochondrial inhibitors rotenone (1 μM) and antimycin A (1 μM) both inhibited hypoxic vasodilatation. Conclusion The present results in porcine coronary arteries suggest NO contributes to hypoxic vasodilation, probably through K channel opening, which is reversed by addition of ET-1 and enhanced by endothelin receptor antagonism. These latter findings suggest that endothelin receptor activation counteracts hypoxic vasodilation.
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Affiliation(s)
- Elise R Hedegaard
- Department of Pharmacology, Aarhus University, Wilhem Meyers Allé 4, Aarhus C, Denmark.
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High-Altitude Exposure in Patients with Cardiovascular Disease: Risk Assessment and Practical Recommendations. Prog Cardiovasc Dis 2010; 52:512-24. [DOI: 10.1016/j.pcad.2010.03.005] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Maisel AS. Cardiovascular and renal surrogate markers in the clinical management of hypertension. Cardiovasc Drugs Ther 2009; 23:317-26. [PMID: 19572190 DOI: 10.1007/s10557-009-6177-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
INTRODUCTION Surrogate markers represent a significant contribution to early diagnosis, longitudinal prognoses, and outcome prediction in cases of hypertension. They often enable detection of disease and disease potential when the disease is still subclinical and are useful noninvasive tools for designing and evaluating therapeutic programs. Surrogate markers are increasingly employed as predictive endpoints for treatment. METHODS Key studies supporting the importance of surrogate markers as diagnostic and prognostic predictors of cardiovascular and renal clinical outcomes in hypertension, as well as what is known about the effects of renin-angiotensin-aldosterone system-blocking agents on these biomarkers were reviewed. RESULTS Clinical data supporting the use of surrogate markers for heart failure, such as brain natriuretic peptide (BNP) and N-terminal prohormone BNP; markers for renal function, such as urinary albumin to creatinine ratio (UACR), urinary albumin excretion rates (UAER), and creatinine, reflecting glomerular filtration; and markers of cardiac remodeling, such as left ventricular hypertrophy and calculations of left ventricular mass index (LVMI), were reviewed for their utility in improving prognosis and treatment efficacy. Finally, hypertension treatment with angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and potentially direct renin inhibitors can significantly improve outcomes predicted by surrogate markers. CONCLUSIONS BNP, UACR, UAER, and LVMI, among others, have been increasingly established as valid surrogate markers with significant value for hypertension prognosis and therapy. The benefits of using surrogate markers to gauge the effectiveness of hypertension therapy in reducing renal and cardiac complications can be seen in improved morbidity and mortality.
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Affiliation(s)
- Alan S Maisel
- Veterans Affairs San Diego Healthcare System, San Diego, CA 92161, USA.
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Wu GB, Zhou EX, Qing DX, Li J. Role of potassium channels in regulation of rat coronary arteriole tone. Eur J Pharmacol 2009; 620:57-62. [DOI: 10.1016/j.ejphar.2009.08.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2009] [Revised: 07/17/2009] [Accepted: 08/04/2009] [Indexed: 11/25/2022]
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Expression of heat shock proteins and nitrotyrosine in small arteries from patients with coronary heart disease. Heart Vessels 2009; 24:260-6. [PMID: 19626397 DOI: 10.1007/s00380-008-1117-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2008] [Accepted: 09/11/2008] [Indexed: 10/20/2022]
Abstract
Heat shock proteins (HSPs) have been suggested to play an important role in the pathogenesis of cardiovascular disease; however, their levels in resistance arteries and their role as useful markers for endothelial dysfunction are not well known. In this paper we studied the levels of HSP90, HSP70, HSP60, HSP27, and of the oxidative stress marker nitrotyrosine (NT) in isolated small subcutaneous arteries from female and male patients with coronary heart disease (CHD) and compared them with healthy controls. HSPs and NT levels were analyzed by immunohistochemistry (IHC) with streptavidin-biotin complex and 3,3'-diaminobenzidine (DAB) staining. The results were assessed with a semi-quantitative method. The study showed lower levels of HSP90 in arteries from both male and female patients when compared to the healthy controls, while levels of HSP70 were lower only in male patients versus controls. The levels of HSP60 and HSP27 did not show any significant difference in either the male or the female groups. NT levels were higher in the arteries from female patients as compared to controls. In conclusion, the present study strengthens the concept that HSPs may play an important role in the pathogenesis of CHD, and that at least two of them, HSP70 and HSP90, may have useful applications as markers of vascular dysfunction in resistance arteries.
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Aggarwal NT, Pfister SL, Gauthier KM, Chawengsub Y, Baker JE, Campbell WB. Chronic hypoxia enhances 15-lipoxygenase-mediated vasorelaxation in rabbit arteries. Am J Physiol Heart Circ Physiol 2008; 296:H678-88. [PMID: 19112096 DOI: 10.1152/ajpheart.00777.2008] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
15-Lipoxygenase (15-LO-1) metabolizes arachidonic acid (AA) to 11,12,15-trihydroxyeicosatrienoic acids (THETAs) and 15-hydroxy-11,12-epoxyeicosatrienoic acids (HEETA) that dilate rabbit arteries. Increased endothelial 15-LO-1 expression enhances arterial relaxations to agonists. We tested the effect of hypoxia on 15-LO-1 expression, THETA and HEETA synthesis, and relaxations in rabbit arteries. The incubation of rabbit aortic endothelial cells and isolated aortas in 0.7% O(2) increased 15-LO-1 expression. Rabbits were housed in a hypoxic atmosphere of 12% O(2) for 5 days. 15-LO-1 expression increased in the endothelium of the arteries of rabbits in 12% O(2) compared with room air. THETA and HEETA synthesis was also enhanced in aortas and mesenteric arteries. AA hyperpolarized the smooth muscle cells in indomethacin- and phenylephrine-treated mesenteric arteries of hypoxic rabbits from -29.4 +/- 1 to -50.1 +/- 3 mV. The hyperpolarization to AA was less in arteries of normoxic rabbits (from -26.0 +/- 2 to -37 +/- 2 mV). This AA-induced hyperpolarization was inhibited by the 15-LO inhibitor BW-755C. Nitric oxide and prostaglandin-independent maximum relaxations to acetylcholine (79.7 +/- 2%) and AA (38.3 +/- 4%) were enhanced in mesenteric arteries from hypoxic rabbits compared with the normoxic rabbits (49.7 +/- 6% and 19.9 +/- 2%, respectively). These relaxations were inhibited by BW-755C and nordihydroguaiaretic acid. Therefore, hypoxia increased the relaxations to agonists in the rabbit mesenteric arteries by enhancing endothelial 15-LO-1 expression and synthesis of the hyperpolarizing factors THETA and HEETA.
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Affiliation(s)
- Nitin T Aggarwal
- Dept. of Pharmacology and Toxicology, Medical College of Wisconsin, 8701 Watertown Plank Rd., Milwaukee, WI 53226, USA
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Huang Y, Giordano FJ. Chapter 13. Oxygen as a direct and indirect biological determinant in the vasculature. Methods Enzymol 2008; 444:285-304. [PMID: 19007670 DOI: 10.1016/s0076-6879(08)02813-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
A fundamental function of the vasculature is to deliver oxygen to tissues and organs. The cells that make up the vasculature also require oxygen, and are acted upon by oxygen in direct and indirect ways that can have significant effects on acute and chronic vascular function and morphology. The role that oxygen, or its absence, plays in defining the biology of the vasculature is thus of critical importance, yet remains an area about which there are many gaps in knowledge and understanding. Oxygen-associated paracrine mechanisms can drive vascular processes such as angiogenesis. The vasculature can also directly sense blood oxygen levels and differentially translate this information into rapid vasoconstriction responses in some vascular beds, and vasodilation in others. Furthering our understanding of how oxygen and hypoxia affect the vasculature may lead to greater insights into the mechanisms and pathogenesis of disease processes involving the vasculature, and lead to new therapeutic paradigms.
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Affiliation(s)
- Yan Huang
- Cardiovascular Medicine, Department of Medicine, and Vascular Biology and Translation Program, Yale University School of Medicine, New Haven, Connecticut, USA
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