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Wang YX, Reyes-García J, Di Mise A, Zheng YM. Role of ryanodine receptor 2 and FK506-binding protein 12.6 dissociation in pulmonary hypertension. J Gen Physiol 2023; 155:213798. [PMID: 36625865 PMCID: PMC9836826 DOI: 10.1085/jgp.202213100] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 07/29/2022] [Accepted: 12/19/2022] [Indexed: 01/11/2023] Open
Abstract
Pulmonary hypertension (PH) is a devastating disease characterized by a progressive increase in pulmonary arterial pressure leading to right ventricular failure and death. A major cellular response in this disease is the contraction of smooth muscle cells (SMCs) of the pulmonary vasculature. Cell contraction is determined by the increase in intracellular Ca2+ concentration ([Ca2+]i), which is generated and regulated by various ion channels. Several studies by us and others have shown that ryanodine receptor 2 (RyR2), a Ca2+-releasing channel in the sarcoplasmic reticulum (SR), is an essential ion channel for the control of [Ca2+]i in pulmonary artery SMCs (PASMCs), thereby mediating the sustained vasoconstriction seen in PH. FK506-binding protein 12.6 (FKBP12.6) strongly associates with RyR2 to stabilize its functional activity. FKBP12.6 can be dissociated from RyR2 by a hypoxic stimulus to increase channel function and Ca2+ release, leading to pulmonary vasoconstriction and PH. More specifically, dissociation of the RyR2-FKBP12.6 complex is a consequence of increased mitochondrial ROS generation mediated by the Rieske iron-sulfur protein (RISP) at the mitochondrial complex III after hypoxia. Overall, RyR2/FKBP12.6 dissociation and the corresponding signaling pathway may be an important factor in the development of PH. Novel drugs and biologics targeting RyR2, FKBP12.6, and related molecules may become unique effective therapeutics for PH.
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Affiliation(s)
- Yong-Xiao Wang
- Department of Molecular and Cellular Physiology, Albany Medical College, Albany, NY, USA,Correspondence to Yong-Xiao Wang:
| | - Jorge Reyes-García
- Department of Molecular and Cellular Physiology, Albany Medical College, Albany, NY, USA,Departamento de Farmacología, Facultad de Medicina, Universidad Nacional Autónoma de México,Ciudad de México, México
| | - Annarita Di Mise
- Department of Molecular and Cellular Physiology, Albany Medical College, Albany, NY, USA,Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
| | - Yun-Min Zheng
- Department of Molecular and Cellular Physiology, Albany Medical College, Albany, NY, USA,Yun-Min Zheng:
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2
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Gierhardt M, Pak O, Walmrath D, Seeger W, Grimminger F, Ghofrani HA, Weissmann N, Hecker M, Sommer N. Impairment of hypoxic pulmonary vasoconstriction in acute respiratory distress syndrome. Eur Respir Rev 2021; 30:30/161/210059. [PMID: 34526314 DOI: 10.1183/16000617.0059-2021] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Accepted: 06/05/2021] [Indexed: 12/29/2022] Open
Abstract
Acute respiratory distress syndrome (ARDS) is a serious complication of severe systemic or local pulmonary inflammation, such as caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. ARDS is characterised by diffuse alveolar damage that leads to protein-rich pulmonary oedema, local alveolar hypoventilation and atelectasis. Inadequate perfusion of these areas is the main cause of hypoxaemia in ARDS. High perfusion in relation to ventilation (V/Q<1) and shunting (V/Q=0) is not only caused by impaired hypoxic pulmonary vasoconstriction but also redistribution of perfusion from obstructed lung vessels. Rebalancing the pulmonary vascular tone is a therapeutic challenge. Previous clinical trials on inhaled vasodilators (nitric oxide and prostacyclin) to enhance perfusion to high V/Q areas showed beneficial effects on hypoxaemia but not on mortality. However, specific patient populations with pulmonary hypertension may profit from treatment with inhaled vasodilators. Novel treatment targets to decrease perfusion in low V/Q areas include epoxyeicosatrienoic acids and specific leukotriene receptors. Still, lung protective ventilation and prone positioning are the best available standard of care. This review focuses on disturbed perfusion in ARDS and aims to provide basic scientists and clinicians with an overview of the vascular alterations and mechanisms of V/Q mismatch, current therapeutic strategies, and experimental approaches.
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Affiliation(s)
- Mareike Gierhardt
- Dept of Internal Medicine, Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Justus-Liebig University, Giessen, Germany.,Excellence Cluster Cardio-Pulmonary Institute (CPI), Giessen, Germany.,Instituto de Investigación en Biomedicina de Buenos Aires (IBioBA) - CONICET - Partner Institute of the Max Planck Society, Buenos Aires, Argentina.,Department of Lung Development and Remodeling, Max Planck Institute for Heart and Lung Research, Member of the German Center for Lung Research (DZL), Member of the Cardio-Pulmonary Institute (CPI) Bad Nauheim, Germany
| | - Oleg Pak
- Dept of Internal Medicine, Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Justus-Liebig University, Giessen, Germany.,Excellence Cluster Cardio-Pulmonary Institute (CPI), Giessen, Germany
| | - Dieter Walmrath
- Dept of Internal Medicine, Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Justus-Liebig University, Giessen, Germany
| | - Werner Seeger
- Dept of Internal Medicine, Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Justus-Liebig University, Giessen, Germany.,Excellence Cluster Cardio-Pulmonary Institute (CPI), Giessen, Germany.,Instituto de Investigación en Biomedicina de Buenos Aires (IBioBA) - CONICET - Partner Institute of the Max Planck Society, Buenos Aires, Argentina.,Institute for Lung Health (ILH), Giessen, Germany
| | - Friedrich Grimminger
- Dept of Internal Medicine, Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Justus-Liebig University, Giessen, Germany.,Excellence Cluster Cardio-Pulmonary Institute (CPI), Giessen, Germany
| | - Hossein A Ghofrani
- Dept of Internal Medicine, Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Justus-Liebig University, Giessen, Germany.,Excellence Cluster Cardio-Pulmonary Institute (CPI), Giessen, Germany.,Dept of Medicine, Imperial College London, London, UK
| | - Norbert Weissmann
- Dept of Internal Medicine, Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Justus-Liebig University, Giessen, Germany.,Excellence Cluster Cardio-Pulmonary Institute (CPI), Giessen, Germany
| | - Matthias Hecker
- Dept of Internal Medicine, Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Justus-Liebig University, Giessen, Germany.,Both authors contributed equally
| | - Natascha Sommer
- Dept of Internal Medicine, Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Justus-Liebig University, Giessen, Germany.,Excellence Cluster Cardio-Pulmonary Institute (CPI), Giessen, Germany.,Both authors contributed equally
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3
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Hypoxic pulmonary vasoconstriction as a regulator of alveolar-capillary oxygen flux: A computational model of ventilation-perfusion matching. PLoS Comput Biol 2021; 17:e1008861. [PMID: 33956786 PMCID: PMC8130924 DOI: 10.1371/journal.pcbi.1008861] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Revised: 05/18/2021] [Accepted: 03/04/2021] [Indexed: 11/19/2022] Open
Abstract
The relationship between regional variabilities in airflow (ventilation) and blood flow (perfusion) is a critical determinant of gas exchange efficiency in the lungs. Hypoxic pulmonary vasoconstriction is understood to be the primary active regulator of ventilation-perfusion matching, where upstream arterioles constrict to direct blood flow away from areas that have low oxygen supply. However, it is not understood how the integrated action of hypoxic pulmonary vasoconstriction affects oxygen transport at the system level. In this study we develop, and make functional predictions with a multi-scale multi-physics model of ventilation-perfusion matching governed by the mechanism of hypoxic pulmonary vasoconstriction. Our model consists of (a) morphometrically realistic 2D pulmonary vascular networks to the level of large arterioles and venules; (b) a tileable lumped-parameter model of vascular fluid and wall mechanics that accounts for the influence of alveolar pressure; (c) oxygen transport accounting for oxygen bound to hemoglobin and dissolved in plasma; and (d) a novel empirical model of hypoxic pulmonary vasoconstriction. Our model simulations predict that under the artificial test condition of a uniform ventilation distribution (1) hypoxic pulmonary vasoconstriction matches perfusion to ventilation; (2) hypoxic pulmonary vasoconstriction homogenizes regional alveolar-capillary oxygen flux; and (3) hypoxic pulmonary vasoconstriction increases whole-lobe oxygen uptake by improving ventilation-perfusion matching. The relationship between regional ventilation (airflow) and perfusion (blood flow) is a major determinant of gas exchange efficiency. Atelactasis and pulmonary vascular occlusive diseases, such as acute pulmonary embolism, are characterized by ventilation-perfusion mismatching and decreased oxygen in the bloodstream. Despite the physiological and medical importance of ventilation-perfusion matching, there are gaps in our knowledge of the regulatory mechanisms that maintain adequate gas exchange under pathological and normal conditions. Hypoxic pulmonary vasoconstriction is understood to be the primary regulator of ventilation-perfusion matching, where upstream arterioles constrict to direct blood flow away from areas that have low oxygen supply, yet it is not understood how this mechanism affects oxygen transport at the system level. In this study we present a computational model of the ventilation-perfusion matching and hypoxic pulmonary vasoconstriction to better understand how physiological regulation at the regional level scales to affect oxygen transport at the system level. Our model simulations predict that this regulatory mechanism improves the spatial overlap of airflow and blood flow, which serves to increase the uptake of oxygen into the bloodstream. This improved understanding of ventilation-perfusion matching may offer insights into the etiology of, and therapeutic interventions for diseases characterized by ventilation-perfusion mismatching.
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Xu B, Gao H, Li D, Hu C, Yang J. Nebulized dexmedetomidine improves pulmonary shunt and lung mechanics during one-lung ventilation: a randomized clinical controlled trial. PeerJ 2020; 8:e9247. [PMID: 32547872 PMCID: PMC7278887 DOI: 10.7717/peerj.9247] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Accepted: 05/07/2020] [Indexed: 12/13/2022] Open
Abstract
Background Dexmedetomidine (Dex), a selective a2-adrenergic receptor agonist, has been previously reported to attenuate intrapulmonary shunt during one-lung ventilation (OLV) and to alleviate bronchoconstriction. However, the therapeutic effects of nebulized Dex on pulmonary shunt and lung mechanics during OLV have not been evaluated. Here we determine whether nebulized dexmedetomidine improved pulmonary shunt and lung mechanics in patients undergoing elective thoracic surgery in a prospective randomized controlled clinical trial. Methods One hundred and twenty-eight patients undergoing elective thoracoscopic surgery were included in this study and randomly divided into four groups: 0.9% saline (Placebo group), 0.5 µg/kg (Dex0.5 group), 1 µg/kg (Dex1 group) and 2 µg/kg (Dex2group) dexmedetomidine. After bronchial intubation, patients received different nebulized doses of dexmedetomidine (0.5 µg/kg, 1 µg/kg and 2 µg/kg) or 0.9% saline placebo during two-lung ventilation(TLV). OLV was initiated 15 min after bronchial intubation. Anesthesia was maintained with intravenous infusion of cisatracurium and propofol. Bispectral Index values were maintained within 40–50 by adjusting the infusion of propofol in all groups. Arterial blood gas samples and central venous blood gas samples were taken as follows: 15 min after bronchial intubation during two-lung ventilation (TLV15), after 30 and 60 min of OLV (OLV30and OLV60, respectively) and 15 min after reinstitution of TLV (ReTLV). Dynamic compliance was also calculated at TLV15, OLV30, OLV60 and ReTLV. Results Dex decreased the requirement of propofol in a dose-dependent manner(P = 0.000). Heart rate (HR) and mean arterial pressure (MAP) displayed no significant difference among groups (P = 0.397 and 0.863). Compared with the placebo group, Dex administered between 0.5 and 2 µg/kg increased partial pressure of oxygen (PaO2) significantly at OLV30 and OLV60(P = 0.000); however, Dex administered between 1 and 2 µg/kg decreased pulmonary shunt fraction (Qs/Qt) at OLV30 and OLV60(P = 0.000). Compared with the placebo group, there were significant increases with dynamic compliance (Cdyn) after OLV in Dex0.5, Dex1 and Dex2group(P = 0.000). Conclusions. Nebulized dexmedetomidine improved oxygenation not only by decreasing pulmonary shunt but also by improving lung compliance during OLV, which may be effective in managing OLV.
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Affiliation(s)
- Bo Xu
- The Department of Anesthesiology, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu, China.,The Department of Anesthesiology, The Affiliated Wuxi People's Hospital of Nanjing Medical University Wuxi, Jiangsu, China
| | - Hong Gao
- The Department of Anesthesiology, The Affiliated Wuxi People's Hospital of Nanjing Medical University Wuxi, Jiangsu, China
| | - Dan Li
- The Department of Anesthesiology, The Affiliated Wuxi People's Hospital of Nanjing Medical University Wuxi, Jiangsu, China
| | - Chunxiao Hu
- The Department of Anesthesiology, The Affiliated Wuxi People's Hospital of Nanjing Medical University Wuxi, Jiangsu, China
| | - Jianping Yang
- The Department of Anesthesiology, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu, China
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5
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Cheng HY, Croft QPP, Frise MC, Talbot NP, Petousi N, Robbins PA, Dorrington KL. Human hypoxic pulmonary vasoconstriction is unaltered by 8 h of preceding isocapnic hyperoxia. Physiol Rep 2018; 5:5/17/e13396. [PMID: 28899910 PMCID: PMC5599860 DOI: 10.14814/phy2.13396] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Revised: 07/28/2017] [Accepted: 07/31/2017] [Indexed: 12/27/2022] Open
Abstract
Exposure to sustained hypoxia of 8 h duration increases the sensitivity of the pulmonary vasculature to acute hypoxia, but it is not known whether exposure to sustained hyperoxia affects human pulmonary vascular control. We hypothesized that exposure to 8 h of hyperoxia would diminish the hypoxic pulmonary vasoconstriction (HPV) that occurs in response to a brief exposure to hypoxia. Eleven healthy volunteers were studied in a crossover protocol with randomization of order. Each volunteer was exposed to acute isocapnic hypoxia (end‐tidal PO2 = 50 mmHg for 10 min) before and after 8 h of hyperoxia (end‐tidal PO2 = 420 mmHg) or euoxia (end‐tidal PO2 = 100 mmHg). After at least 3 days, each volunteer returned and was exposed to the other condition. Systolic pulmonary artery pressure (an index of HPV) and cardiac output were measured, using Doppler echocardiography. Eight hours of hyperoxia had no effect on HPV or the response of cardiac output to acute hypoxia.
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Affiliation(s)
- Hung-Yuan Cheng
- Department of Physiology, Anatomy & Genetics, University of Oxford, Oxford, United Kingdom
| | - Quentin P P Croft
- Department of Physiology, Anatomy & Genetics, University of Oxford, Oxford, United Kingdom
| | - Matthew C Frise
- Department of Physiology, Anatomy & Genetics, University of Oxford, Oxford, United Kingdom
| | - Nick P Talbot
- Department of Physiology, Anatomy & Genetics, University of Oxford, Oxford, United Kingdom
| | - Nayia Petousi
- Department of Physiology, Anatomy & Genetics, University of Oxford, Oxford, United Kingdom
| | - Peter A Robbins
- Department of Physiology, Anatomy & Genetics, University of Oxford, Oxford, United Kingdom
| | - Keith L Dorrington
- Department of Physiology, Anatomy & Genetics, University of Oxford, Oxford, United Kingdom
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6
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Brugniaux JV, Coombs GB, Barak OF, Dujic Z, Sekhon MS, Ainslie PN. Highs and lows of hyperoxia: physiological, performance, and clinical aspects. Am J Physiol Regul Integr Comp Physiol 2018; 315:R1-R27. [PMID: 29488785 DOI: 10.1152/ajpregu.00165.2017] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Molecular oxygen (O2) is a vital element in human survival and plays a major role in a diverse range of biological and physiological processes. Although normobaric hyperoxia can increase arterial oxygen content ([Formula: see text]), it also causes vasoconstriction and hence reduces O2 delivery in various vascular beds, including the heart, skeletal muscle, and brain. Thus, a seemingly paradoxical situation exists in which the administration of oxygen may place tissues at increased risk of hypoxic stress. Nevertheless, with various degrees of effectiveness, and not without consequences, supplemental oxygen is used clinically in an attempt to correct tissue hypoxia (e.g., brain ischemia, traumatic brain injury, carbon monoxide poisoning, etc.) and chronic hypoxemia (e.g., severe COPD, etc.) and to help with wound healing, necrosis, or reperfusion injuries (e.g., compromised grafts). Hyperoxia has also been used liberally by athletes in a belief that it offers performance-enhancing benefits; such benefits also extend to hypoxemic patients both at rest and during rehabilitation. This review aims to provide a comprehensive overview of the effects of hyperoxia in humans from the "bench to bedside." The first section will focus on the basic physiological principles of partial pressure of arterial O2, [Formula: see text], and barometric pressure and how these changes lead to variation in regional O2 delivery. This review provides an overview of the evidence for and against the use of hyperoxia as an aid to enhance physical performance. The final section addresses pathophysiological concepts, clinical studies, and implications for therapy. The potential of O2 toxicity and future research directions are also considered.
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Affiliation(s)
| | - Geoff B Coombs
- Centre for Heart, Lung, and Vascular Health, University of British Columbia , Kelowna, British Columbia , Canada
| | - Otto F Barak
- Faculty of Medicine, University of Novi Sad, Novi Sad, Serbia.,Faculty of Sport and Physical Education, University of Novi Sad, Novi Sad, Serbia
| | - Zeljko Dujic
- Department of Integrative Physiology, School of Medicine, University of Split , Split , Croatia
| | - Mypinder S Sekhon
- Centre for Heart, Lung, and Vascular Health, University of British Columbia , Kelowna, British Columbia , Canada.,Division of Critical Care Medicine, Department of Medicine, Vancouver General Hospital, University of British Columbia , Vancouver, British Columbia , Canada
| | - Philip N Ainslie
- Centre for Heart, Lung, and Vascular Health, University of British Columbia , Kelowna, British Columbia , Canada
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