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Ehrlich RS, Dasgupta S, Jessup RE, Teppang KL, Shiao AL, Jeoung KY, Su X, Shivkumar A, Theodorakis EA, Paesani F, Yang J. Excited State Rotational Freedom Impacts Viscosity Sensitivity in Arylcyanoamide Fluorescent Molecular Rotor Dyes. J Phys Chem B 2024; 128:3946-3952. [PMID: 38624216 DOI: 10.1021/acs.jpcb.4c00033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/17/2024]
Abstract
The microviscosity of intracellular environments plays an important role in monitoring cellular function. Thus, the capability of detecting changes in viscosity can be utilized for the detection of different disease states. Viscosity-sensitive fluorescent molecular rotors are potentially excellent probes for these applications; however, the predictable relationships between chemical structural features and viscosity sensitivity are poorly understood. Here, we investigate a set of arylcyanoamide-based fluorescent probes and the effect of small aliphatic substituents on their viscosity sensitivity. We found that the location of the substituents and the type of π-network of the fluorophore can significantly affect the viscosity sensitivity of these fluorophores. Computational analysis supported the notion that the excited state rotational energy barrier plays a dominant role in the relative viscosity sensitivity of these fluorophores. These findings provide valuable insight into the design of molecular rotor-based fluorophores for viscosity measurement.
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Affiliation(s)
- Rachel S Ehrlich
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0358, United States
| | - Saswata Dasgupta
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0358, United States
| | - R Erin Jessup
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0358, United States
| | - Kristine L Teppang
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0358, United States
| | - Alexander L Shiao
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0358, United States
| | - Kun Yong Jeoung
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0358, United States
| | - Xuanmin Su
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0358, United States
| | - Aashish Shivkumar
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0358, United States
| | - Emmanuel A Theodorakis
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0358, United States
| | - Francesco Paesani
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0358, United States
| | - Jerry Yang
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0358, United States
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2
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Vasquez-Hidalgo MA, Grazul-Bilska AT, Swanson KC, Perry GA, Vonnahme KA. Timing and duration of nutrient restriction and its impacts on placental development and umbilical blood flow in adolescent sheep. Theriogenology 2023; 209:21-30. [PMID: 37354757 DOI: 10.1016/j.theriogenology.2023.06.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 06/10/2023] [Accepted: 06/11/2023] [Indexed: 06/26/2023]
Abstract
We hypothesized that nutrient restriction from day 50-90 of gestation decreases umbilical blood flow and that umbilical blood flow would recover to control values upon realimentation during late gestation (d 90 to 130) or remain reduced in ewes that continued to be nutrient restricted. On d 50 of gestation, young nulliparous whiteface ewes (6-8 mo; n = 41) carrying singletons were randomly assigned to two dietary treatments: 100% of NRC recommendations (CON) or 60% of CON (RES). On d 90 of gestation, ewes either remained on CON or RES until d 130, or CON ewes were RES from d 90 to 130, or RES ewes were realimented to CON from d 90 to 130. This resulted in 4 treatment groups on day 130: CON-CON, CON-RES, RES-RES, RES-CON. Umbilical blood flow and fetal and placental measurements were obtained via ultrasonography every 10 days from day 50-110. Non-survival surgeries were performed on days 50, 90, and 130 (n = 6-7 ewes/group) where uterine artery and umbilical blood flows were measured during surgery via ultrasonography. Conceptus weights were recorded and placentomes collected to determine binucleate cell numbers. The study was conducted as a completely randomized design arrangement with repeated measures. Data were analyzed using the MIXED procedure of SAS. There was a nutritional treatment by day interaction (P < 0.01) with CON ewes having greater umbilical blood flow compared with RES by d 90. Fetal biparietal distance, abdominal width, and kidney area increased (P < 0.05) in CON-RES with all these measurements increasing during late gestation. We partially accept our hypothesis as nutrient restriction during mid gestation decreased umbilical blood flow. However, blood flow did not return to control levels upon realimentation. By d 130, fetal and placental weights were similar between RES-RES and CON-CON. Binucleate cell numbers in the fetal trophoblast were not influenced by nutritional treatments. Our findings suggest that refeeding previously nutrient restricted pregnant adolescent ewes to control levels does not reestablish umbilical blood flow. Adequate placental development during mid gestation could protect the fetus from a decreased umbilical blood flow later in gestation when nutrients were limited by 40%.
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Affiliation(s)
- M A Vasquez-Hidalgo
- Department of Animal Sciences, North Dakota State University, Dept 7630 PO Box 6050, Fargo, ND, 58108-6050, USA
| | - A T Grazul-Bilska
- Department of Animal Sciences, North Dakota State University, Dept 7630 PO Box 6050, Fargo, ND, 58108-6050, USA
| | - K C Swanson
- Department of Animal Sciences, North Dakota State University, Dept 7630 PO Box 6050, Fargo, ND, 58108-6050, USA
| | - G A Perry
- Texas A&M AgriLife Research and Extension Center, 1710 FM 3053 N, Overton, Tx, 75684, USA
| | - K A Vonnahme
- Department of Animal Sciences, North Dakota State University, Dept 7630 PO Box 6050, Fargo, ND, 58108-6050, USA.
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Sakinah S, Priya SP, Mok PL, Munisvaradass R, Teh SW, Sun Z, Alzahrani B, Abu Bakar F, Chee HY, Awang Hamat R, He G, Xiong C, Joseph N, Tong JB, Wu X, Maniam M, Samrot AV, Higuchi A, Kumar SS. Stem Cell Therapy in Dengue Virus-Infected BALB/C Mice Improves Hepatic Injury. Front Cell Dev Biol 2021; 9:637270. [PMID: 34291043 PMCID: PMC8287336 DOI: 10.3389/fcell.2021.637270] [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: 12/03/2020] [Accepted: 05/25/2021] [Indexed: 01/02/2023] Open
Abstract
Extensive clinical efforts have been made to control the severity of dengue diseases; however, the dengue morbidity and mortality have not declined. Dengue virus (DENV) can infect and cause systemic damage in many organs, resulting in organ failure. Here, we present a novel report showing a tailored stem-cell-based therapy that can aid in viral clearance and rescue liver cells from further damage during dengue infection. We administered a combination of hematopoietic stem cells and endothelial progenitor cells in a DENV-infected BALB/c mouse model and found that delivery of this cell cocktail had improved their liver functions, confirmed by hematology, histopathology, and next-generation sequencing. These stem and progenitor cells can differentiate into target cells and repair the damaged tissues. In addition, the regime can regulate endothelial proliferation and permeability, modulate inflammatory reactions, enhance extracellular matrix production and angiogenesis, and secrete an array of growth factors to create an enhanced milieu for cell reparation. No previous study has been published on the treatment of dengue infection using stem cells combination. In conclusion, dengue-induced liver damage was rescued by administration of stem cell therapy, with less apoptosis and improved repair and regeneration in the dengue mouse model.
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Affiliation(s)
- S Sakinah
- Department of Medical Microbiology, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Seri Kembangan, Malaysia
| | - Sivan Padma Priya
- Department of Medical Microbiology, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Seri Kembangan, Malaysia
| | - Pooi Ling Mok
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, Jouf University, Sakakah, Saudi Arabia.,Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Seri Kembangan, Malaysia
| | - Rusheni Munisvaradass
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Seri Kembangan, Malaysia
| | - Seoh Wei Teh
- Department of Medical Microbiology, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Seri Kembangan, Malaysia
| | - Zhong Sun
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Seri Kembangan, Malaysia
| | - Badr Alzahrani
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, Jouf University, Sakakah, Saudi Arabia
| | - Faizal Abu Bakar
- Bioinformatics and Computational Biology, Malaysia Genome Institute, National Institute of Biotechnology Malaysia (NIBM), Kajang, Malaysia
| | - Hui-Yee Chee
- Department of Medical Microbiology, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Seri Kembangan, Malaysia
| | - Rukman Awang Hamat
- Department of Medical Microbiology, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Seri Kembangan, Malaysia
| | - Guozhong He
- Institute of Health, Kunming Medical University, Kunming, China
| | - Chenglong Xiong
- Department of Medical Microbiology, School of Public Health, Fudan University, Shanghai, China
| | - Narcisse Joseph
- Department of Medical Microbiology, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Seri Kembangan, Malaysia
| | - Jia Bei Tong
- Department of Medical Microbiology, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Seri Kembangan, Malaysia
| | - Xiaoyun Wu
- First Affiliated Hospital of Baotou Medical College, Inner Mongolia University of Science and Technology, Baotou, China
| | - Mahendran Maniam
- First Affiliated Hospital of Baotou Medical College, Inner Mongolia University of Science and Technology, Baotou, China
| | - Antony V Samrot
- School of Bioscience, Faculty of Medicine, Bioscience and Nursing, MAHSA University, Jenjarom, Malaysia
| | - Akon Higuchi
- Department of Chemical and Materials Engineering, National Central University, Taoyuan City, Taiwan.,R&D Center for Membrane Technology, Chung Yuan Christian University, Taoyuan City, Taiwan
| | - S Suresh Kumar
- Department of Medical Microbiology, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Seri Kembangan, Malaysia.,Centre for Materials Engineering and Regenerative Medicine, Bharath Institute of Higher Education and Research, Chennai, India
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Kim IS, Lee BK, Yang PS, Joung B, Kim JY. Sex-based Approach for the Clinical Impact of the Increased Hemoglobin on Incident AF in the General Population. Korean Circ J 2020; 50:1095-1110. [PMID: 33258318 PMCID: PMC7707984 DOI: 10.4070/kcj.2020.0412] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2020] [Revised: 10/12/2020] [Accepted: 11/03/2020] [Indexed: 12/12/2022] Open
Abstract
Background and Objectives Although the adverse cardiovascular effect of anemia has been well described, the effect of polycythemia on the incident atrial fibrillation (AF) remain unclear. The objective of this study is to identify the association between increased hemoglobin and incident AF. Methods This was a retrospective-cohort study with 434,269 subjects who underwent national health examinations from the Korean National Sample Cohort. We estimated the risk of incident AF according to hemoglobin-based four-categories. Results During 3.9-year of follow-up, polycythemia group showed higher incidences of AF (hazard ratio[HR] with 95% confidence interval[CI], 1.50 [1.28–1.76] and 1.69 [1.13–2.56]; in men and women, respectively) than normal hemoglobin group (each p<0.001). In the normal hemoglobin and polycythemia groups, a 1 g/dL increase in hemoglobin level was associated with increased risks of incident AF (1.12 [1.07–1.17] and 1.18 [1.10–1.26] in men and women, each p<0.001). To investigate the specific hemoglobin concentration related to greater AF incidence, we analyzed the sensitivity/specificity of different hemoglobin levels: ≥16.0 g/dL in men and ≥14.5 g/dL in women showed the highest Youden's index, with c-indices of 0.83 and 0.82, respectively. Kaplan-Meier cumulative-event curves according to these specific hemoglobin levels (≥16.0 g/dL in men and ≥14.5 g/dL in women) also showed consistent results in both sexes (each p<0.05). Conclusions Even in the Korean general population, increased hemoglobin was significantly associated with higher rate of incident AF. Especially, subjects with hemoglobin levels ≥14.5 g/dL in women and ≥16.0 g/dL among men were associated with increased risk of incident AF.
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Affiliation(s)
- In Soo Kim
- Division of Cardiology, Department of Internal Medicine, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Byoung Kwon Lee
- Division of Cardiology, Department of Internal Medicine, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Pil Sung Yang
- Department of Cardiology, CHA Bundang Medical Center, CHA University, Seongnam, Korea
| | - Boyoung Joung
- Division of Cardiology, Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea
| | - Jong Youn Kim
- Division of Cardiology, Department of Internal Medicine, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
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5
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Tremblay JC, Ainslie PN, Turner R, Gatterer H, Schlittler M, Woyke S, Regli IB, Strapazzon G, Rauch S, Siebenmann C. Endothelial function and shear stress in hypobaric hypoxia: time course and impact of plasma volume expansion in men. Am J Physiol Heart Circ Physiol 2020; 319:H980-H994. [PMID: 32886005 DOI: 10.1152/ajpheart.00597.2020] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
High-altitude exposure typically reduces endothelial function, and this is modulated by hemoconcentration resulting from plasma volume contraction. However, the specific impact of hypobaric hypoxia independent of external factors (e.g., cold, varying altitudes, exercise, diet, and dehydration) on endothelial function is unknown. We examined the temporal changes in blood viscosity, shear stress, and endothelial function and the impact of plasma volume expansion (PVX) during exposure to hypobaric hypoxia while controlling for external factors. Eleven healthy men (25 ± 4 yr, mean ± SD) completed two 4-day chamber visits [normoxia (NX) and hypobaric hypoxia (HH; equivalent altitude, 3,500 m)] in a crossover design. Endothelial function was assessed via flow-mediated dilation in response to transient (reactive hyperemia; RH-FMD) and sustained (progressive handgrip exercise; SS-FMD) increases in shear stress before entering and after 1, 6, 12, 48, and 96 h in the chamber. During HH, endothelial function was also measured on the last day after PVX to preexposure levels (1,140 ± 320 mL balanced crystalloid solution). Blood viscosity and arterial shear stress increased on the first day during HH compared with NX and remained elevated at 48 and 96 h (P < 0.005). RH-FMD did not differ during HH compared with NX and was unaffected by PVX despite reductions in blood viscosity (P < 0.05). The stimulus-response slope of increases in shear stress to vasodilation during SS-FMD was preserved in HH and increased by 44 ± 73% following PVX (P = 0.023). These findings suggest that endothelial function is maintained in HH when other stressors are absent and that PVX improves endothelial function in a shear-stress stimulus-specific manner.NEW & NOTEWORTHY Using a normoxic crossover study design, we examined the impact of hypobaric hypoxia (4 days; altitude equivalent, 3,500 m) and hemoconcentration on blood viscosity, shear stress, and endothelial function. Blood viscosity increased during the hypoxic exposure and was accompanied by elevated resting and exercising arterial shear stress. Flow-mediated dilation stimulated by reactive hyperemia and handgrip exercise was preserved throughout the hypoxic exposure. Plasma volume expansion reversed the hypoxia-associated hemoconcentration and selectively increased handgrip exercise flow-mediated dilation.
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Affiliation(s)
- Joshua C Tremblay
- Centre for Heart, Lung and Vascular Health, University of British Columbia-Okanagan, Kelowna, Canada
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, University of British Columbia-Okanagan, Kelowna, Canada
| | - Rachel Turner
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy
| | - Hannes Gatterer
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy
| | - Maja Schlittler
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy
| | - Simon Woyke
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy.,Department of Anesthesiology and Intensive Care Medicine, Medical University of Innsbruck, Innsbruck, Austria
| | - Ivo B Regli
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy.,Department of Anesthesia and Intensive Care Medicine, "F. Tappeiner" Hospital, Merano, Italy
| | - Giacomo Strapazzon
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy.,Department of Anesthesiology and Intensive Care Medicine, Medical University of Innsbruck, Innsbruck, Austria
| | - Simon Rauch
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy.,Department of Anesthesia and Intensive Care Medicine, "F. Tappeiner" Hospital, Merano, Italy
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6
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Kim IS, Lee BK, Yang PS, Joung B, Kim JY. Sex-based approach for the clinical impact of polycythaemia on cardiovascular outcomes in the general population. Eur J Prev Cardiol 2020; 29:869-879. [PMID: 33624094 DOI: 10.1093/eurjpc/zwaa071] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 06/06/2020] [Accepted: 09/07/2020] [Indexed: 12/30/2022]
Abstract
AIMS Although the adverse cardiovascular effect of anaemia has been well described, the effect of polycythaemia on the cardiovascular outcomes of the general population remain unclear. The primary objective is to identify the association between polycythaemia and major adverse cardiovascular events (MACE), and the secondary objective is to identify the specific haemoglobin concentration more associated with an increased risk for MACE. METHODS AND RESULTS This was a retrospective cohort study, 451 107 subjects were enrolled who underwent national health examinations from the Korean National Sample Cohort. We estimated the risk of MACE, a composite of cardiovascular mortality, incident myocardial infarction (MI), and stroke according to haemoglobin-based four categories. During 3.8-year of follow-up, polycythaemia group showed higher MACE [hazard ratio (HR) = 1.27 (1.13-1.44) and HR = 1.76 (1.08-2.88); in men and women, respectively], incident MI [HR = 1.37 (1.05-1.79) and HR = 3.46 (1.06-14.00)], and incident ischaemic stroke [HR = 1.27 (1.10-1.46) and HR = 1.72 (1.02-2.91)] than normal haemoglobin group (P < 0.001 in all cases). In the normal haemoglobin and polycythaemia groups, a 1 g/dL increase in haemoglobin level was associated with increased risks of MACE [HR = 1.04 (1.01-1.07) and HR = 1.05 (1.01-1.10) in men and women, each P < 0.05]. To investigate the specific haemoglobin concentration related to greater MACE incidence, we analysed the sensitivity/specificity of different haemoglobin levels: ≥16.5 g/dL in men and ≥15.0 g/dL in women showed the highest Youden's index (sensitivity + specificity - 1), with c-indices of 0.82 (0.81-0.83) and 0.83 (0.82-0.84), respectively. CONCLUSION Even in the Korean general population, polycythaemia was significantly associated with higher rates of MACE, incident MI, and incident ischaemic stroke. Especially, subjects with haemoglobin levels ≥15.0 g/dL in women and ≥16.5 g/dL among men were associated with increased risks of MACE.
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Affiliation(s)
- In-Soo Kim
- Division of Cardiology, Department of Internal Medicine, Yonsei University College of Medicine, 211 Eonju-ro Gangnam-gu, Seoul 06273, Republic of Korea.,Division of Cardiology, Department of Internal Medicine, Gangnam Severance Hospital, Yonsei University College of Medicine, 211 Eonju-ro Gangnam-gu, Seoul 06273, Republic of Korea
| | - Byoung Kwon Lee
- Division of Cardiology, Department of Internal Medicine, Gangnam Severance Hospital, Yonsei University College of Medicine, 211 Eonju-ro Gangnam-gu, Seoul 06273, Republic of Korea
| | - Pil-Sung Yang
- Department of Cardiology, CHA Bundang Medical Center, CHA University, 59 Yatap-ro, Seongnam 13496, Republic of Korea
| | - Boyoung Joung
- Division of Cardiology, Department of Internal Medicine, Yonsei University College of Medicine, 211 Eonju-ro Gangnam-gu, Seoul 06273, Republic of Korea
| | - Jong-Youn Kim
- Division of Cardiology, Department of Internal Medicine, Gangnam Severance Hospital, Yonsei University College of Medicine, 211 Eonju-ro Gangnam-gu, Seoul 06273, Republic of Korea
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7
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Tymko MM, Tremblay JC, Bailey DM, Green DJ, Ainslie PN. The impact of hypoxaemia on vascular function in lowlanders and high altitude indigenous populations. J Physiol 2019; 597:5759-5776. [PMID: 31677355 DOI: 10.1113/jp277191] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 10/07/2019] [Indexed: 12/18/2022] Open
Abstract
Exposure to hypoxia elicits widespread physiological responses that are critical for successful acclimatization; however, these responses may induce apparent maladaptive consequences. For example, recent studies conducted in both the laboratory and the field (e.g. at high altitude) have demonstrated that endothelial function is reduced in hypoxia. Herein, we review the several proposed mechanism(s) pertaining to the observed reduction in endothelial function in hypoxia including: (i) changes in blood flow patterns (i.e. shear stress), (ii) increased inflammation and production of reactive oxygen species (i.e. oxidative stress), (iii) heightened sympathetic nerve activity, and (iv) increased red blood cell concentration and mass leading to elevated nitric oxide scavenging. Although some of these mechanism(s) have been examined in lowlanders, less in known about endothelial function in indigenous populations that have chronically adapted to environmental hypoxia for millennia (e.g. the Peruvian, Tibetan and Ethiopian highlanders). There is some evidence indicating that healthy Tibetan and Peruvian (i.e. Andean) highlanders have preserved endothelial function at high altitude, but less is known about the Ethiopian highlanders. However, Andean highlanders suffering from chronic mountain sickness, which is characterized by an excessive production of red blood cells, have markedly reduced endothelial function. This review will provide a framework and mechanistic model for vascular endothelial adaptation to hypoxia in lowlanders and highlanders. Elucidating the pathways responsible for vascular adaption/maladaptation to hypoxia has potential clinical implications for disease featuring low oxygen delivery (e.g. heart failure, pulmonary disease). In addition, a greater understanding of vascular function at high altitude will clinically benefit the global estimated 85 million high altitude residents.
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Affiliation(s)
- Michael M Tymko
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, British Columbia, Canada.,Faculty of Physical Education and Recreation, University of Alberta, Edmonton, Alberta, Canada
| | - Joshua C Tremblay
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, British Columbia, Canada
| | - Damian M Bailey
- Neurovascular Research Laboratory, Faculty of Life Sciences and Education, University of South Wales, UK
| | - Daniel J Green
- Cardiovascular Research Group, School of Human Sciences (Exercise and Sport Science), University of Western Australia, Perth, Australia.,Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, British Columbia, Canada
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8
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Tremblay JC, Hoiland RL, Howe CA, Coombs GB, Vizcardo-Galindo GA, Figueroa-Mujíca RJ, Bermudez D, Gibbons TD, Stacey BS, Bailey DM, Tymko MM, MacLeod DB, Gasho C, Villafuerte FC, Pyke KE, Ainslie PN. Global REACH 2018: High Blood Viscosity and Hemoglobin Concentration Contribute to Reduced Flow-Mediated Dilation in High-Altitude Excessive Erythrocytosis. Hypertension 2019; 73:1327-1335. [PMID: 31006327 DOI: 10.1161/hypertensionaha.119.12780] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Excessive erythrocytosis (EE; hemoglobin concentration [Hb] ≥21 g/dL in adult males) is associated with increased cardiovascular risk in highlander Andeans. We sought to quantify shear stress and assess endothelial function via flow-mediated dilation (FMD) in male Andeans with and without EE. We hypothesized that FMD would be impaired in Andeans with EE after accounting for shear stress and that FMD would improve after isovolemic hemodilution. Brachial artery shear stress and FMD were assessed in 23 male Andeans without EE (age: 40±15 years [mean±SD]; Hb<21 g/dL) and 19 male Andeans with EE (age: 43±14 years; Hb≥21 g/dL) in Cerro de Pasco, Peru (4330 m). Shear stress was quantified from Duplex ultrasound measures of shear rate and blood viscosity. In a subset of participants (n=8), FMD was performed before and after isovolemic hemodilution with blood volume replaced by an equal volume of human serum albumin. Blood viscosity and Hb were 48% and 23% higher (both P<0.001) and FMD was 28% lower after adjusting for the shear stress stimulus ( P=0.013) in Andeans with EE compared to those without. FMD was inversely correlated with blood viscosity ( r2=0.303; P<0.001) and Hb ( r2=0.230; P=0.001). Isovolemic hemodilution decreased blood viscosity by 30±10% and Hb by 14±5% (both P<0.001) and improved shear stress stimulus-adjusted FMD from 2.7±1.9% to 4.3±1.9% ( P=0.022). Hyperviscosity, high Hb, or both, actively contribute to acutely reversible impairments in FMD in EE, suggesting that this plays a pathogenic role in the increased cardiovascular risk.
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Affiliation(s)
- Joshua C Tremblay
- From the Cardiovascular Stress Response Laboratory, School of Kinesiology and Health Studies, Queen's University, Kingston, ON, Canada (J.C.T., K.E.P.)
| | - Ryan L Hoiland
- Centre for Heart, Lung & Vascular Health, Faculty of Health and Social Development, University of British Columbia-Okanagan, Kelowna, Canada (R.L.H., C.A.H., G.B.C., M.M.T., P.N.A.)
| | - Connor A Howe
- Centre for Heart, Lung & Vascular Health, Faculty of Health and Social Development, University of British Columbia-Okanagan, Kelowna, Canada (R.L.H., C.A.H., G.B.C., M.M.T., P.N.A.)
| | - Geoff B Coombs
- Centre for Heart, Lung & Vascular Health, Faculty of Health and Social Development, University of British Columbia-Okanagan, Kelowna, Canada (R.L.H., C.A.H., G.B.C., M.M.T., P.N.A.)
| | - Gustavo A Vizcardo-Galindo
- Laboratorio de Fisiología Comparada, Departamento de Ciencias Biológicas y Fisiológicas, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Perú (G.A.V.-G., R.J.F.-M., D.B., F.C.V.)
| | - Rómulo J Figueroa-Mujíca
- Laboratorio de Fisiología Comparada, Departamento de Ciencias Biológicas y Fisiológicas, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Perú (G.A.V.-G., R.J.F.-M., D.B., F.C.V.)
| | - Daniela Bermudez
- Laboratorio de Fisiología Comparada, Departamento de Ciencias Biológicas y Fisiológicas, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Perú (G.A.V.-G., R.J.F.-M., D.B., F.C.V.)
| | - Travis D Gibbons
- School of Physical Education, Sport and Exercise Sciences, Division of Sciences, University of Otago, Dunedin, New Zealand (T.D.G.)
| | - Benjamin S Stacey
- Neurovascular Research Laboratory, Faculty of Life Sciences and Education, University of South Wales, United Kingdom (B.S.S., D.M.B.)
| | - Damian M Bailey
- Neurovascular Research Laboratory, Faculty of Life Sciences and Education, University of South Wales, United Kingdom (B.S.S., D.M.B.)
| | - Michael M Tymko
- Centre for Heart, Lung & Vascular Health, Faculty of Health and Social Development, University of British Columbia-Okanagan, Kelowna, Canada (R.L.H., C.A.H., G.B.C., M.M.T., P.N.A.)
| | - David B MacLeod
- Human Pharmacology and Physiology Laboratory, Department of Anesthesiology, Duke University Medical Center, Durham, NC (D.B.M.)
| | - Chris Gasho
- Division of Pulmonary, Critical Care, Hyperbaric and Sleep Medicine, Loma Linda University School of Medicine, CA (C.G.)
| | - Francisco C Villafuerte
- Laboratorio de Fisiología Comparada, Departamento de Ciencias Biológicas y Fisiológicas, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Perú (G.A.V.-G., R.J.F.-M., D.B., F.C.V.)
| | - Kyra E Pyke
- From the Cardiovascular Stress Response Laboratory, School of Kinesiology and Health Studies, Queen's University, Kingston, ON, Canada (J.C.T., K.E.P.)
| | - Philip N Ainslie
- Centre for Heart, Lung & Vascular Health, Faculty of Health and Social Development, University of British Columbia-Okanagan, Kelowna, Canada (R.L.H., C.A.H., G.B.C., M.M.T., P.N.A.)
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9
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Tremblay JC, Coombs GB, Howe CA, Vizcardo-Galindo GA, Figueroa-Mujíca RJ, Bermudez D, Tymko MM, Villafuerte FC, Ainslie PN, Pyke KE. Global Reach 2018: reduced flow-mediated dilation stimulated by sustained increases in shear stress in high-altitude excessive erythrocytosis. Am J Physiol Heart Circ Physiol 2019; 317:H991-H1001. [PMID: 31441692 DOI: 10.1152/ajpheart.00316.2019] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Excessive erythrocytosis [EE; hemoglobin concentration (Hb) ≥ 21 g/dL in adult men] is a maladaptive high-altitude pathology associated with increased cardiovascular risk and reduced reactive hyperemia flow-mediated dilation (FMD); however, whether a similar impairment occurs in response to more commonly encountered sustained increases in shear stress [sustained stimulus (SS)-FMD] over a range of overlapping stimuli is unknown. We characterized SS-FMD in response to handgrip exercise in Andeans with and without EE in Cerro de Pasco, Peru (4,330 m). Andean highlanders with EE (n = 17, Hb = 23.2 ± 1.2 g/dL) and without EE (n = 23, Hb = 18.7 ± 1.9 g/dL) performed 3 min of rhythmic handgrip exercise at 20, 35, and 50% of maximum voluntary contraction (MVC). Duplex ultrasound was used to continuously record blood velocity and diameter in the brachial artery, and blood viscosity was measured to accurately calculate shear stress. Although baseline shear stress did not differ, Andeans with EE had 22% lower shear stress than Andeans without at 50% MVC (P = 0.004). At 35 and 50% MVC, SS-FMD was 2.1 ± 2.0 and 2.8 ± 2.7% in Andeans with EE compared with 4.1 ± 3.4 and 7.5 ± 4.5% in those without (P = 0.048 and P < 0.001). The stimulus-response slope (∆shear stress vs. ∆diameter) was lower in Andeans with EE compared with Andeans without (P = 0.028). This slope was inversely related to Hb in Andeans with EE (r2 = 0.396, P = 0.007). A reduced SS-FMD in response to small muscle mass exercise in Andeans with EE indicates a generalized reduction in endothelial sensitivity to shear stress, which may contribute to increased cardiovascular risk in this population.NEW & NOTEWORTHY High-altitude excessive erythrocytosis (EE; hemoglobin concentration ≥ 21 g/dL) is a maladaptation to chronic hypoxia exposure and is associated with increased cardiovascular risk. We examined flow-mediated dilation (FMD) in response to sustained elevations in shear stress achieved using progressive handgrip exercise [sustained stimulus (SS)-FMD] in Andean highlanders with and without EE at 4,330 m. Andeans with EE demonstrated lower SS-FMD compared with those without. Heightened hemoglobin concentration was related to lower SS-FMD in Andeans with EE.
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Affiliation(s)
- Joshua C Tremblay
- Cardiovascular Stress Response Laboratory, School of Kinesiology and Health Studies, Queen's University, Kingston, Ontario, Canada
| | - Geoff B Coombs
- Centre for Heart, Lung and Vascular Health, Faculty of Health and Social Development, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
| | - Connor A Howe
- Centre for Heart, Lung and Vascular Health, Faculty of Health and Social Development, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
| | - Gustavo A Vizcardo-Galindo
- Laboratorio de Fisiología Comparada, Departamento de Ciencias Biológicas y Fisiológicas, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Perú
| | - Rómulo J Figueroa-Mujíca
- Laboratorio de Fisiología Comparada, Departamento de Ciencias Biológicas y Fisiológicas, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Perú
| | - Daniela Bermudez
- Laboratorio de Fisiología Comparada, Departamento de Ciencias Biológicas y Fisiológicas, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Perú
| | - Michael M Tymko
- Centre for Heart, Lung and Vascular Health, Faculty of Health and Social Development, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
| | - Francisco C Villafuerte
- Laboratorio de Fisiología Comparada, Departamento de Ciencias Biológicas y Fisiológicas, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Perú
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, Faculty of Health and Social Development, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
| | - Kyra E Pyke
- Cardiovascular Stress Response Laboratory, School of Kinesiology and Health Studies, Queen's University, Kingston, Ontario, Canada
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10
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Brun JF, Varlet-Marie E, Richou M, Mercier J, Raynaud de Mauverger E. Blood rheology as a mirror of endocrine and metabolic homeostasis in health and disease1. Clin Hemorheol Microcirc 2018; 69:239-265. [PMID: 29660919 DOI: 10.3233/ch-189124] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Rheological properties of plasma and blood cells are markedly influenced by the surrounding milieu: physicochemical factors, metabolism and hormones. Acid/base status, osmolality, lipid status, plasma protein pattern, oxidative stress induced by increased free radicals production, endothelium-derived factors such as nitric oxide (NO), achidonic acid derivatives modulate both red blood cell (RBC) and white cell mechanics. Therefore, regulatory axes involving liver, endothelium, kidney, pancreas, adrenal gland, endocrine heart, adipose tissue, pituitary gland, and surely other tissues play important roles in the regulation of blood fluidity. A comprehensive picture of all this complex network of regulatory loops is still unavailable but current progress of knowledge suggest that some attempts can currently be made.
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Affiliation(s)
- Jean-Frédéric Brun
- U1046 INSERM, UMR 9214 CNRS « Physiopathologie and Médecine Expérimentale du Coeur et des Muscles-PHYMEDEXP », Unité d'ExplorationsMétaboliques (CERAMM), Université de Montpellier, Département de Physiologie Clinique, Hôpital Lapeyronie CHRU Montpellier, France
| | - Emmanuelle Varlet-Marie
- Institut des Biomolécules Max Mousseron (IBMM) UMR CNRS 5247, Université de Montpellier, Ecole Nationale Supérieure de Chimie de Montpellier, France.,Laboratoire de Biophysique and Bio-Analyses, Faculté de Pharmacie, Université de Montpellier, France
| | - Marlène Richou
- U1046 INSERM, UMR 9214 CNRS « Physiopathologie and Médecine Expérimentale du Coeur et des Muscles-PHYMEDEXP », Unité d'ExplorationsMétaboliques (CERAMM), Université de Montpellier, Département de Physiologie Clinique, Hôpital Lapeyronie CHRU Montpellier, France
| | - Jacques Mercier
- U1046 INSERM, UMR 9214 CNRS « Physiopathologie and Médecine Expérimentale du Coeur et des Muscles-PHYMEDEXP », Unité d'ExplorationsMétaboliques (CERAMM), Université de Montpellier, Département de Physiologie Clinique, Hôpital Lapeyronie CHRU Montpellier, France
| | - Eric Raynaud de Mauverger
- U1046 INSERM, UMR 9214 CNRS « Physiopathologie and Médecine Expérimentale du Coeur et des Muscles-PHYMEDEXP », Unité d'ExplorationsMétaboliques (CERAMM), Université de Montpellier, Département de Physiologie Clinique, Hôpital Lapeyronie CHRU Montpellier, France
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11
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Chan YL, Han ST, Li CH, Wu CC, Chen KF. Transfusion of Red Blood Cells to Patients with Sepsis. Int J Mol Sci 2017; 18:ijms18091946. [PMID: 28891973 PMCID: PMC5618595 DOI: 10.3390/ijms18091946] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Revised: 08/26/2017] [Accepted: 09/08/2017] [Indexed: 12/14/2022] Open
Abstract
Sepsis is one of the major causes of death worldwide, and is the host response to infection which renders our organs malfunctioning. Insufficient tissue perfusion and oxygen delivery have been implicated in the pathogenesis of sepsis-related organ dysfunction, making transfusion of packed red blood cells (pRBCs) a reasonable treatment modality. However, clinical trials have generated controversial results. Even the notion that transfused pRBCs increase the oxygen-carrying capacity of blood has been challenged. Meanwhile, during sepsis, the ability of our tissues to utilize oxygen may also be reduced, and the increased blood concentrations of lactate may be the results of strong inflammation and excessive catecholamine release, rather than impaired cell respiration. Leukodepleted pRBCs more consistently demonstrated improvement in microcirculation, and the increase in blood viscosity brought about by pRBC transfusion helps maintain functional capillary density. A restrictive strategy of pRBC transfusion is recommended in treating septic patients.
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Affiliation(s)
- Yi-Ling Chan
- Department of Emergency Medicine, Chang Gung Memorial Hospital Linkou, Taoyuan 330, Taiwan.
| | - Shih-Tsung Han
- Department of Emergency Medicine, Chang Gung Memorial Hospital Linkou, Taoyuan 330, Taiwan.
| | - Chih-Huang Li
- Department of Emergency Medicine, Chang Gung Memorial Hospital Linkou, Taoyuan 330, Taiwan.
| | - Chin-Chieh Wu
- Department of Emergency Medicine, Chang Gung Memorial Hospital Keelung, Keelung 204, Taiwan.
| | - Kuan-Fu Chen
- Department of Emergency Medicine, Chang Gung Memorial Hospital Linkou, Taoyuan 330, Taiwan.
- Department of Emergency Medicine, Chang Gung Memorial Hospital Keelung, Keelung 204, Taiwan.
- Clinical Informatics and Medical Statistics Research Center, Chang Gung University, Taoyuan 330, Taiwan.
- Community Medicine Research Center, Chang Gung Memorial Hospital Keelung, Keelung 204, Taiwan.
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12
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Piety NZ, Reinhart WH, Stutz J, Shevkoplyas SS. Optimal hematocrit in an artificial microvascular network. Transfusion 2017; 57:2257-2266. [PMID: 28681482 DOI: 10.1111/trf.14213] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Revised: 05/03/2017] [Accepted: 05/11/2017] [Indexed: 12/18/2022]
Abstract
BACKGROUND Higher hematocrit increases the oxygen-carrying capacity of blood but also increases blood viscosity, thus decreasing blood flow through the microvasculature and reducing the oxygen delivery to tissues. Therefore, an optimal value of hematocrit that maximizes tissue oxygenation must exist. STUDY DESIGN AND METHODS We used viscometry and an artificial microvascular network device to determine the optimal hematocrit in vitro. Suspensions of fresh red blood cells (RBCs) in plasma, normal saline, or a protein-containing buffer and suspensions of stored red blood cells (at Week 6 of standard hypothermic storage) in plasma with hematocrits ranging from 10 to 80% were evaluated. RESULTS For viscometry, optimal hematocrits were 10, 25.2, 31.9, 37.1, and 37.5% for fresh RBCs in plasma at shear rates of 3.2 or less, 11.0, 27.7, 69.5, and 128.5 inverse seconds. For the artificial microvascular network, optimal hematocrits were 51.1, 55.6, 59.2, 60.9, 62.3, and 64.6% for fresh RBCs in plasma and 46.4, 48.1, 54.8, 61.4, 65.7, and 66.5% for stored RBCs in plasma at pressures of 2.5, 5, 10, 20, 40, and 60 cm H2 O. CONCLUSION Although exact optimal hematocrit values may depend on specific microvascular architecture, our results suggest that the optimal hematocrit for oxygen delivery in the microvasculature depends on perfusion pressure. Therefore, anemia in chronic disorders may represent a beneficial physiological response to reduced perfusion pressure resulting from decreased heart function and/or vascular stenosis. Our results may help explain why a therapeutically increasing hematocrit in such conditions with RBC transfusion frequently leads to worse clinical outcomes.
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Affiliation(s)
- Nathaniel Z Piety
- Department of Biomedical Engineering, Cullen College of Engineering, University of Houston, Houston, Texas
| | | | - Julianne Stutz
- Department of Biomedical Engineering, Cullen College of Engineering, University of Houston, Houston, Texas
| | - Sergey S Shevkoplyas
- Department of Biomedical Engineering, Cullen College of Engineering, University of Houston, Houston, Texas
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13
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Brun JF, Varlet-Marie E, Raynaud de Mauverger E. Hematocrit and hematocrit viscosity ratio during exercise in athletes: Even closer to predicted optimal values? Clin Hemorheol Microcirc 2017; 64:777-787. [PMID: 27767965 DOI: 10.3233/ch-168012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The hemorheological theory of optimal hematocrit suggests that the best value of hematocrit (hct) should be that which results in the highest value of the hematocrit/viscosity (h/η) ratio. Trained athletes compared to sedentary subjects have a lower hct, but a higher h/η, and endurance training reduces the discrepancy between the actual hct and the ⪡ideal⪢ hct that can be predicted with a theoretical curve of h/η vs hct constructed with Quemada's model. In this study we investigated what becomes this homeostasis of h/η and hct during acute exercise in 19 athletes performing a 25 min exercise test. VO2max is negatively correlated to resting hct and positively correlated to discrepancy between actual and ideal resting hct which is correlated to the maximal rise in hct during exercise. Predicted and actual values of the h/η were fairly correlated (r = 0.970 p < 0.001) but the actual value was lower at rest and this discrepancy vanished at 25 min exercise. Exercise-induced decrease in discrepancy between actual and theoretical h/η was negatively correlated with the score of overtraining. All these findings suggest that h/η is a regulated parameter and that its model-predicted ⪡optimal⪢ values yield a ⪡theoretical optimal⪢ hct which is close to the actual value and even closer when athletes are well trained. In addition, acute exercise sets h/η closer from its predicted ideal value and this adaptation is impaired when athletes quote elevated scores on the overtraining questionnaire.
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Affiliation(s)
- Jean-Frédéric Brun
- UMR CNRS 9214-Inserm U1046 ⪡ Physiopathologie & Médecine Expérimentale du Cœur etdes Muscles - PHYMEDEXP ⪢, Unité d'Explorations Métaboliques (CERAMM), Université de Montpellier, Département de Physiologie Clinique, Hôpital Lapeyronie CHU Montpellier, France
| | - Emmanuelle Varlet-Marie
- Institut des Biomolécules Max Mousseron (IBMM) UMR CNRS 5247, Université de Montpellier, Ecole Nationale Supérieure de Chimie de Montpellier, France.,Laboratoire de Biophysique & Bio-Analyses, Faculté de Pharmacie, Université de Montpellier, France
| | - Eric Raynaud de Mauverger
- UMR CNRS 9214-Inserm U1046 ⪡ Physiopathologie & Médecine Expérimentale du Cœur etdes Muscles - PHYMEDEXP ⪢, Unité d'Explorations Métaboliques (CERAMM), Université de Montpellier, Département de Physiologie Clinique, Hôpital Lapeyronie CHU Montpellier, France
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14
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Brun JF, Varlet-Marie E, Fédou C, Raynaud de Mauverger E. « Optimal » vs actual hematocrit in obesity and overweight. Clin Hemorheol Microcirc 2016; 64:593-601. [PMID: 27767966 DOI: 10.3233/ch-168013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Equations of blood viscosity provide a prediction of the 'optimal' hematocrit' (hct) as the hct resulting in the highest value of the bell-shaped curve of hematocrit/viscosity ratio h/η. We investigated if overweight and obesity have an influence on these parameters. We compared 32 normal weight subjects, 40 overweight (BMI 25-30) and 38 obese subjects. There was no difference in the theoretical curve of h/η. The actual h/η is the same in the 3 groups but is always higher than the theoretical h/η in all groups. The actual h/η is lower in overweight than controls (p = 0.011). Modeling yields the same value of theoretical optimal hct across BMI classes. The 3 groups have the same values of actual hct, but actual is significantly lower than optimal in all cases (p < 0.001). Hematocrit is lower than predicted due to a discrepancy between predicted and actual h/η which is due to the inter-subject variability of RBC rigidity ... The discrepancy between optimal and actual h/η is negatively correlated to RBC rigidity indexes even if the model uses a fixed value of these indexes. Thus keeping in mind that the optimal hct should not be the same in the various parts of the vascular bed, its theoretical prediction with Quemada's equation appears to predict a value higher than actual hematocrit but well correlated to it, and the agreement between optimal and actual hct is dependent on RBC flexibility. This leads to think that the body sets hematocrit below its ideal value in sedentary subjects in order to cope with the need of increasing blood viscosity factors in case of exercise without impairing O2 supply to tissues.
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Affiliation(s)
- Jean-Frédéric Brun
- UMR CNRS 9214-Inserm U1046 « Physiopathologie & Médecine Expérimentale du Coeur et des Muscles - PHYMEDEXP », Unité d'Explorations Métaboliques (CERAMM), Université de Montpellier, Département de Physiologie Clinique,Hôpital Lapeyronie CHU Montpellier, France
| | - Emmanuelle Varlet-Marie
- Institut des Biomolécules Max Mousseron (IBMM) UMR CNRS 5247, Université de Montpellier, Ecole Nationale Supérieure de Chimie de Montpellier, France.,Laboratoire de Biophysique & Bio-Analyses, Faculté de Pharmacie, Université de Montpellier, France
| | - Christine Fédou
- UMR CNRS 9214-Inserm U1046 « Physiopathologie & Médecine Expérimentale du Coeur et des Muscles - PHYMEDEXP », Unité d'Explorations Métaboliques (CERAMM), Université de Montpellier, Département de Physiologie Clinique,Hôpital Lapeyronie CHU Montpellier, France
| | - Eric Raynaud de Mauverger
- UMR CNRS 9214-Inserm U1046 « Physiopathologie & Médecine Expérimentale du Coeur et des Muscles - PHYMEDEXP », Unité d'Explorations Métaboliques (CERAMM), Université de Montpellier, Département de Physiologie Clinique,Hôpital Lapeyronie CHU Montpellier, France
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15
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Affiliation(s)
- Andre F. Palmer
- William G. Lowrie Department of Chemical and Biomolecular Engineering, The Ohio State University, Columbus, Ohio 43210;
| | - Marcos Intaglietta
- Department of Bioengineering, University of California, San Diego, La Jolla, California 92093;
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16
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Ong PK, Kim S. Effect of erythrocyte aggregation on spatiotemporal variations in cell-free layer formation near on arteriolar bifurcation. Microcirculation 2014; 20:440-53. [PMID: 23360227 DOI: 10.1111/micc.12045] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2012] [Accepted: 01/24/2013] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To investigate how red blood cell aggregation could modulate the spatial variations in cell-free layer formation in the vicinity of an arteriolar bifurcation. METHODS Visualization of blood flow was performed in upstream and downstream vessels of arteriolar bifurcations in the rat cremaster muscles under reduced flow conditions before and after induction of red blood cell aggregation to both physiological normal- and pathological hyperlevels seen in humans. RESULTS Large asymmetries of layer widths on opposite sides of the downstream vessel were attenuated along the vessel and this effect could be prominently enhanced by the hyperaggregation due to a higher formation rate of the layer which was greater on one side than the other of the vessel. The proportion of downstream layer formation constituted by the smaller downstream vessel generally increased with a thicker layer width at the wall of the upstream vessel adjacent it. A greater tendency of the layer formation in the smaller downstream vessel was found under the hyperaggregating condition than normal-aggregating and nonaggregating conditions. CONCLUSION Red blood cell aggregation could attenuate the asymmetry in cell-free layer formation on opposite sides of the downstream vessel, but enhances the heterogeneity of the layer formation between downstream vessels.
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Affiliation(s)
- Peng Kai Ong
- Department of Bioengineering & Department of Surgery, National University of Singapore, Singapore
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17
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Rusak T, Misztal T, Piszcz J, Tomasiak M. Nitric oxide scavenging by cell-free hemoglobin may be a primary factor determining hypertension in polycythemic patients. Free Radic Res 2013; 48:230-8. [PMID: 24180690 DOI: 10.3109/10715762.2013.860225] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
We tested the hypothesis that hypertension associated with polycythemia vera (PV) may be related to hemoglobin released from erythrocytes (cell-free hemoglobin, fHb). We assessed hematocrit, mean arterial pressure (MAP), blood viscosity, and the level of fHb and nitrite/nitrate (NOx) in the plasma of 73 PV patients and 38 healthy controls. The effect of isovolemic erythrocytapheresis (ECP) on the considered parameters was also studied. From the whole group of PV patients a subset of subjects with normal (normotensive patients, n = 16) and elevated MAP (hypertensive patients, n = 57) can be subtracted. It was found that in comparison with healthy controls, PV patients have significantly (p ≤ 0.01) elevated Hct (0.567 vs. 0.422), blood viscosity (5.45 vs. 3.56 cP), MAP (106.8 vs. 93.8 mmHg), plasma fHb (9.7 vs. 2.8 mg/dL), and NOx levels (34.1 vs. 27.5 μM). Compared with normotensive patients, hypertensive PV patients demonstrated a higher rise in fHb (10.2 vs. 8.0) and plasma NOx levels (35.8 vs. 31.0). In PV patients, fHb positively correlates with MAP (r = 0.489), NOx levels (r = 0.461), hematocrit (r = 0.428), and viscosity (r = 0.393). Blood viscosity positively correlated with hematocrit (r = 0.894), but not with other considered parameters. In PV patients MAP poorly correlated with hematocrit, whereas the correlation between MAP and NOx altered from - 0.325 (healthy control) to + 0.268 (PV patients). ECP procedure was associated with a significant (p < 0.01) reduction of hematocrit, fHb, blood viscosity, and MAP. In the normotensive subgroup of PV patients the ECP procedure did not affect MAP. It can be concluded that accelerated scavenging of nitric oxide by fHb rather than high Hct may be a key factor determining the development of hypertension in PV patients.
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Affiliation(s)
- T Rusak
- Department of Physical Chemistry, Medical University of Bialystok , Bialystok , Poland
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18
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Morel N, Biais M, Delaunay F, Dubuisson V, Cassone O, Siméon F, Morel O, Janvier G. [Erythrocytes and microvascular tone during acute traumatic haemorrhagic shock]. ACTA ACUST UNITED AC 2013; 32:339-46. [PMID: 23611789 DOI: 10.1016/j.annfar.2013.02.025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2012] [Accepted: 02/28/2013] [Indexed: 10/26/2022]
Abstract
Haemorrhagic shock remains a leading cause of death in trauma patients. The concept of haematologic damage control is gradually taking place in the management of traumatic haemorrhagic shock. It is based primarily on the early implementation of a quality blood transfusion involving erythrocytes, plasmas and platelets transfusion. Red blood cell transfusion is mainly supported by the oxygen carrier properties of erythrocytes. However, it appears that erythrocytes ability to modulate the bioavailability of nitric oxide (NO) plays a major role in capillary opening and perfusion. Erythrocytes are also actively involved in the processes of hemostasis and coagulation. In this context, it seems difficult to define a threshold of hemoglobin concentration to determine the implementation of a blood transfusion in traumatic haemorrhagic shock.
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Affiliation(s)
- N Morel
- Service de réanimation des urgences, pôle des urgences adultes, hôpital Pellegrin, place Raba-Léon, Bordeaux, France.
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Yürük K, Milstein DMJ, Bezemer R, Bartels SA, Biemond BJ, Ince C. Transfusion of banked red blood cells and the effects on hemorrheology and microvascular hemodynamics in anemic hematology outpatients. Transfusion 2012; 53:1346-52. [PMID: 22998160 DOI: 10.1111/j.1537-2995.2012.03905.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND The aim of this study was to investigate the effects of red blood cell (RBC) transfusion on the hemorrheologic properties and microcirculatory hemodynamics in anemic hematology outpatients receiving 2 to 4 RBC units of either "fresh" (leukoreduced storage for less than 1 week) or "aged" (leukoreduced storage for 3-4 weeks) RBCs. STUDY DESIGN AND METHODS Measurements were performed before and 30 minutes after RBC transfusion in hematology outpatients. Leukoreduced RBC suspensions were stored in saline-adenine-glucose-mannitol (SAGM) additive solution. Whole blood viscosity was measured using Couette low-shear viscometry, RBC deformability and aggregability were measured using laser-assisted optical rotational cell analysis, and microcirculatory density and perfusion were assessed using sidestream dark field imaging. RESULTS One group of patients (n = 10) received a median (interquartile range) of 3 (2-3) RBC bags that were stored for 7 (5-7) days (fresh) and the other group of patients (n = 10) received 3 (3-3) RBC bags that were stored for 23 (22-28) days (aged). After transfusion of fresh versus aged RBCs, hematocrit increased to 32 ± 3% versus 31 ± 2% (p < 0.363), whole blood viscosity increased to 4.2 ± 0.4 Pa/sec versus 4.2 ± 0.6 Pa/sec (p < 0.912), RBC deformability index remained unaffected, RBC aggregability index increased to 55 ± 10 versus 55 ± 13 (p = 0.967), microcirculatory flow remained unaffected, and microcirculatory density increased to 19.3 ± 2.5 mm/mm(2) versus 18.7 ± 1.9 mm/mm(2) (p = 0.595), respectively. CONCLUSION Storing leukoreduced SAGM-suspended RBCs for 3 to 4 weeks did not affect their ability to improve hemorrheologic properties and microcirculatory hemodynamics in our small group of anemic hematology outpatients. Larger studies are needed to confirm this finding.
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Affiliation(s)
- Koray Yürük
- Department of Translational Physiology, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
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Sriram K, Salazar Vázquez BY, Tsai AG, Cabrales P, Intaglietta M, Tartakovsky DM. Autoregulation and mechanotransduction control the arteriolar response to small changes in hematocrit. Am J Physiol Heart Circ Physiol 2012; 303:H1096-106. [PMID: 22923620 DOI: 10.1152/ajpheart.00438.2012] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Here, we present an analytic model of arteriolar mechanics that accounts for key autoregulation mechanisms, including the myogenic response and the vasodilatory effects of nitric oxide (NO) in the vasculature. It couples the fluid mechanics of blood flow in arterioles with solid mechanics of the vessel wall and includes the effects of wall shear stress- and stretch-induced endothelial NO production. The model can be used to describe the regulation of blood flow and NO transport under small changes in hematocrit and to analyze the regulatory response of arterioles to small changes in hematocrit. Our analysis revealed that the experimentally observed paradoxical increase in cardiac output with small increases in hematocrit results from the combination of increased NO production and the effects of a strong myogenic response modulated by elevated levels of WSS. Our findings support the hypothesis that vascular resistance varies inversely with blood viscosity for small changes in hematocrit in a healthy circulation that responds to shear stress stimuli. They also suggest beneficial effects independent of changes in O(2) carrying capacity associated with the postsurgical transfusion of one or two units of blood.
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Affiliation(s)
- Krishna Sriram
- Department of Mechanical and Aerospace Engineering, University of California-San Diego, La Jolla, California 92093-0412, USA
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21
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Owusu BY, Stapley R, Patel RP. Nitric oxide formation versus scavenging: the red blood cell balancing act. J Physiol 2012; 590:4993-5000. [PMID: 22687616 DOI: 10.1113/jphysiol.2012.234906] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Nitric oxide (NO) is a key modulator of vascular homeostasis controlling critical functions related to blood flow, respiration, cell death and proliferation, and protecting the vasculature from pro-inflammatory and coagulative stresses. Inhibition of NO formation, and/or diversion of NO away from its physiological signalling targets lead to dysregulated NO bioavailability, a hallmark of numerous vascular and pulmonary diseases. Current concepts suggest that the balance between NO formation and NO scavenging is critical in disease development, with the corollary being that redressing the balance offers a target for therapeutic intervention. Evidence presented over the last two decades has seen red blood cells (RBCs) and haemoglobin specifically emerge as prominent effectors in this paradigm. In this symposium review article, we discuss recent insights into the mechanisms by which RBCs may modulate the balance between NO-formation and inhibition. We discuss how these mechanisms may become dysfunctional to cause disease, highlight key questions that remain, and discuss the potential impact of these insights on therapeutic opportunities.
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Affiliation(s)
- Benjamin Y Owusu
- Department of Pathology, University of Alabama at Birmingham, 901 19th Street South, BMRII 532, Birmingham, AL 35294, USA
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22
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Baek JH, D'Agnillo F, Vallelian F, Pereira CP, Williams MC, Jia Y, Schaer DJ, Buehler PW. Hemoglobin-driven pathophysiology is an in vivo consequence of the red blood cell storage lesion that can be attenuated in guinea pigs by haptoglobin therapy. J Clin Invest 2012; 122:1444-58. [PMID: 22446185 DOI: 10.1172/jci59770] [Citation(s) in RCA: 233] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Accepted: 02/08/2012] [Indexed: 01/19/2023] Open
Abstract
Massive transfusion of blood can lead to clinical complications, including multiorgan dysfunction and even death. Such severe clinical outcomes have been associated with longer red blood cell (rbc) storage times. Collectively referred to as the rbc storage lesion, rbc storage results in multiple biochemical changes that impact intracellular processes as well as membrane and cytoskeletal properties, resulting in cellular injury in vitro. However, how the rbc storage lesion triggers pathophysiology in vivo remains poorly defined. In this study, we developed a guinea pig transfusion model with blood stored under standard blood banking conditions for 2 (new), 21 (intermediate), or 28 days (old blood). Transfusion with old but not new blood led to intravascular hemolysis, acute hypertension, vascular injury, and kidney dysfunction associated with pathophysiology driven by hemoglobin (Hb). These adverse effects were dramatically attenuated when the high-affinity Hb scavenger haptoglobin (Hp) was administered at the time of transfusion with old blood. Pathologies observed after transfusion with old blood, together with the favorable response to Hp supplementation, allowed us to define the in vivo consequences of the rbc storage lesion as storage-related posttransfusion hemolysis producing Hb-driven pathophysiology. Hb sequestration by Hp might therefore be a therapeutic modality for enhancing transfusion safety in severely ill or massively transfused patients.
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Affiliation(s)
- Jin Hyen Baek
- Laboratory of Biochemistry and Vascular Biology, Division of Hematology, Center for Biologics Evaluation and Research, FDA, Bethesda, Maryland 20892, USA
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23
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Ong PK, Jain S, Kim S. Spatio-temporal variations in cell-free layer formation near bifurcations of small arterioles. Microvasc Res 2012; 83:118-25. [DOI: 10.1016/j.mvr.2011.11.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2011] [Revised: 10/09/2011] [Accepted: 11/02/2011] [Indexed: 10/15/2022]
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24
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Gender differences in myogenic regulation along the vascular tree of the gerbil cochlea. PLoS One 2011; 6:e25659. [PMID: 21980520 PMCID: PMC3183064 DOI: 10.1371/journal.pone.0025659] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2011] [Accepted: 09/09/2011] [Indexed: 11/20/2022] Open
Abstract
Regulation of cochlear blood flow is critical for hearing due to its exquisite sensitivity to ischemia and oxidative stress. Many forms of hearing loss such as sensorineural hearing loss and presbyacusis may involve or be aggravated by blood flow disorders. Animal experiments and clinical outcomes further suggest that there is a gender preference in hearing loss, with males being more susceptible. Autoregulation of cochlear blood flow has been demonstrated in some animal models in vivo, suggesting that similar to the brain, blood vessels supplying the cochlea have the ability to control flow within normal limits, despite variations in systemic blood pressure. Here, we investigated myogenic regulation in the cochlear blood supply of the Mongolian gerbil, a widely used animal model in hearing research. The cochlear blood supply originates at the basilar artery, followed by the anterior inferior cerebellar artery, and inside the inner ear, by the spiral modiolar artery and the radiating arterioles that supply the capillary beds of the spiral ligament and stria vascularis. Arteries from male and female gerbils were isolated and pressurized using a concentric pipette system. Diameter changes in response to increasing luminal pressures were recorded by laser scanning microscopy. Our results show that cochlear vessels from male and female gerbils exhibit myogenic regulation but with important differences. Whereas in male gerbils, both spiral modiolar arteries and radiating arterioles exhibited pressure-dependent tone, in females, only radiating arterioles had this property. Male spiral modiolar arteries responded more to L-NNA than female spiral modiolar arteries, suggesting that NO-dependent mechanisms play a bigger role in the myogenic regulation of male than female gerbil cochlear vessels.
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25
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Hightower CM, Salazar Vázquez BY, Woo Park S, Sriram K, Martini J, Yalcin O, Tsai AG, Cabrales P, Tartakovsky DM, Johnson PC, Intaglietta M. Integration of cardiovascular regulation by the blood/endothelium cell-free layer. WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2011; 3:458-70. [PMID: 21523919 DOI: 10.1002/wsbm.150] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The cell-free layer (CFL) width separating red blood cells in flowing blood from the endothelial cell membrane is shown to be a regulator of the balance between nitric oxide (NO) production by the endothelium and NO scavenging by blood hemoglobin. The CFL width is determined by hematocrit (Hct) and the vessel wall flow velocity gradient. These factors and blood and plasma viscosity determine vessel wall shear stress which regulates the production of NO in the vascular wall. Mathematical modeling and experimental findings show that vessel wall NO concentration is a strong nonlinear function of Hct and that small Hct variations have comparatively large effects on blood pressure regulation. Furthermore, NO concentration is a regulator of inflammation and oxygen metabolism. Therefore, small, sustained perturbations of Hct may have long-term effects that can promote pro-hypertensive and pro-inflammatory conditions. In this context, Hct and its variability are directly related to vascular tone, peripheral vascular resistance, oxygen transport and delivery, and inflammation. These effects are relevant to the analysis and understanding of blood pressure regulation, as NO bioavailability regulates the contractile state of blood vessels. Furthermore, regulation of the CFL is a direct function of blood composition therefore understanding of its physiology relates to the design and management of fluid resuscitation fluids. From a medical perspective, these studies propose that it should be of clinical interest to note small variations in patient's Hct levels given their importance in modulating the CFL width and therefore NO bioavailability. WIREs Syst Biol Med 2011 3 458-470 DOI: 10.1002/wsbm.150
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Affiliation(s)
- C Makena Hightower
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, USA
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26
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Ong PK, Jain S, Namgung B, Woo YI, Sakai H, Lim D, Chun KJ, Kim S. An automated method for cell-free layer width determination in small arterioles. Physiol Meas 2011; 32:N1-12. [PMID: 21252418 DOI: 10.1088/0967-3334/32/3/n01] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Histogram-based thresholding techniques utilized for cell-free layer width measurement in arteriolar flow may produce an overestimation of the layer width since they do not consider faint shaded regions near the vessel wall as part of the erythrocyte column. To address this problem, we developed a new method for detecting the boundary of the erythrocyte column based on an edge detection algorithm. This automated method (grayscale method) provides local detections of the inner vessel wall as well as the boundary between the cell-free layer and the erythrocyte column without binarization of grayscale images. The cell-free layer width measurements using the grayscale method and existing techniques (minimum method and Otsu's method) were compared with those determined manually in arteriolar flows of the rat cremaster muscle. In the absence of the shaded regions, values obtained by the grayscale method and minimum method were statistically in good agreement with the manual method but not in the case of Otsu's method. When the faint shaded regions were present, the grayscale method appeared to produce more accurate results than the minimum method and Otsu's method.
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Affiliation(s)
- P K Ong
- Division of Bioengineering and Department of Surgery, National University of Singapore, Singapore
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27
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Sriram K, Vázquez BYS, Yalcin O, Johnson PC, Intaglietta M, Tartakovsky DM. The effect of small changes in hematocrit on nitric oxide transport in arterioles. Antioxid Redox Signal 2011; 14:175-85. [PMID: 20560785 PMCID: PMC3014765 DOI: 10.1089/ars.2010.3266] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
We report the development of a mathematical model that quantifies the effects of small changes in systemic hematocrit (Hct) on the transport of nitric oxide (NO) in the microcirculation. The model consists of coupled transport equations for NO and oxygen (O2) and accounts for both shear-induced NO production by the endothelium and the effect of changing systemic Hct on the rate of NO production and the rate of NO scavenging by red blood cells. To incorporate the dependence of the plasma layer width on changes in Hct, the model couples the hemodynamics of blood in arterioles with NO and O2 transport in the plasma layer. A sensitivity analysis was conducted to determine the effects of uncertain model parameters (the thicknesses of endothelial surface layers and diffusion coefficients of NO and O2 in muscle tissues and vascular walls) on the model's predictions. Our analysis reveals that small increases in Hct may raise NO availability in the vascular wall. This finding sheds new light on the experimental data that show that the blood circulation responds to systematic increases of Hct in a manner that is consistent with increasing NO production followed by a plateau.
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Affiliation(s)
- Krishna Sriram
- Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, California 92093-0412, USA
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28
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Vázquez BYS, Martini J, Tsai AG, Johnson PC, Cabrales P, Intaglietta M. The variability of blood pressure due to small changes of hematocrit. Am J Physiol Heart Circ Physiol 2010; 299:H863-7. [PMID: 20601464 DOI: 10.1152/ajpheart.00496.2010] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The hematocrit (Hct) of awake hamsters was lowered to 90% of baseline by isovolemic hemodilution using hamster plasma to determine the acute effect of small changes in Hct and blood viscosity on systemic hemodynamics. Mean arterial blood pressure increased, reaching a maximum of about 10% above baseline (8.6 +/- 5.5 mmHg) when Hct decreased 8.4 +/- 1.9% (P < 0.005). Cardiac output increased continuously with hemodilution. These conditions were reached at approximately 60 min after exchange transfusion and remained stationary for 1 h. Peripheral vascular resistance was approximately constant up to a decrease of Hct of about 10% and then fell continuously with lowering Hct. Vascular hindrance or vascular resistance independent of blood viscosity increased by about 20% and remained at this level up to an Hct decrease of 20%, indicating that the vasculature constricted with the lowered Hct. The results for the initial 2-h period are opposite but continuous with previous findings with small increases in Hct. In conclusion, limited acute anemic conditions increase mean arterial blood pressure during the initial period of 2 h, an effect that is quantitatively similar but opposite to the acute increase of Hct during the same period.
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29
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Perfusion vs. oxygen delivery in transfusion with "fresh" and "old" red blood cells: the experimental evidence. Transfus Apher Sci 2010; 43:69-78. [PMID: 20646963 DOI: 10.1016/j.transci.2010.05.011] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We review the experimental evidence showing systemic and microvascular effects of blood transfusions instituted to support the organism in extreme hemodilution and hemorrhagic shock, focusing on the use of fresh vs. stored blood as a variable. The question: "What does a blood transfusion remedy?" was analyzed in experimental models addressing systemic and microvascular effects showing that oxygen delivery is not the only function that must be addressed. In extreme hemodilution and hemorrhagic shock blood transfusions simultaneously restore blood viscosity and oxygen carrying capacity, the former being critically needed for re-establishing a functional mechanical environment of the microcirculation, necessary for obtaining adequate capillary blood perfusion. Increased oxygen affinity due to 2,3 DPG depletion is shown to have either no effect or a positive oxygenation effect, when the transfused red blood cells (RBCs) do not cause additional flow impairment due to structural malfunctions including increased rigidity and release of hemoglobin. It is concluded that fresh RBCs are shown to be superior to stored RBCs in transfusion, however increased oxygen affinity may be a positive factor in hemorrhagic shock resuscitation. Although experimental studies seldom reproduce emergency and clinical conditions, nonetheless they serve to explore fundamental physiological mechanisms in the microcirculation that cannot be directly studied in humans.
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30
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Gundersen SI, Chen G, Palmer AF. Mathematical model of NO and O2 transport in an arteriole facilitated by hemoglobin based O2 carriers. Biophys Chem 2009; 143:1-17. [PMID: 19318228 PMCID: PMC2717632 DOI: 10.1016/j.bpc.2009.02.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2009] [Revised: 02/10/2009] [Accepted: 02/10/2009] [Indexed: 01/01/2023]
Abstract
The increasing demand for donated human blood has spurred research to develop hemoglobin-based O(2) carriers (HBOCs) that can be used as red blood cell (RBC) substitutes. However, in vivo studies of acellular HBOCs have shown an increase in mean arterial pressure following transfusion that has been attributed to the HBOC's ability to scavenge NO (an important vasodilator that is synthesized by endothelial cells in the blood vessel wall that signals neighboring smooth muscle cells to relax). In this study, a mathematical model was developed to describe NO and O(2) transport in an arteriole containing a mixture of acellular HBOCs and RBCs. The acellular HBOCs studied in this work possessed a wide range of O(2) affinities, O(2) dissociation rate constants and NO reactivities in order to evaluate their effect on O(2) tension and NO concentration in the arteriole tissue region. By focusing on the concentration of NO that is localized in the arteriole smooth muscle cell region, the model can predict the vasopressor response of HBOCs. The results of this study confirmed that acellular HBOCs scavenge large amounts of NO from the entire arteriole (approximately 50% or more NO compared to RBCs only). A recombinant Hb, rHb3011, displayed the least NO reactivity and consequently left the most NO remaining in the arteriole. The NO concentration in the arteriole with respect to the other HBOCs studied was proportional to their NO reactivity. Therefore, the results of this study demonstrate that NO scavenging is an unavoidable consequence of transfusing HBOCs. To prevent or reduce vasodilatation, we suggest administration of NO by either inhaling NO or transfusing nitrite into the blood stream followed by transfusion of HBOC.
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Affiliation(s)
- Sharon Irene Gundersen
- The Ohio State University Department of Chemical and Biomolecular Engineering 140 West 19 Avenue Columbus, OH 43210
| | - Guo Chen
- The Ohio State University Department of Chemical and Biomolecular Engineering 140 West 19 Avenue Columbus, OH 43210
| | - Andre Francis Palmer
- The Ohio State University Department of Chemical and Biomolecular Engineering 140 West 19 Avenue Columbus, OH 43210
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31
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Vázquez BYS, Vázquez MAS, Intaglietta M, de Faire U, Fagrell B, Cabrales P. Hematocrit and mean arterial blood pressure in pre- and postmenopause women. Vasc Health Risk Manag 2009; 5:483-8. [PMID: 19554088 PMCID: PMC2697582 DOI: 10.2147/vhrm.s5798] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2009] [Indexed: 11/23/2022] Open
Abstract
The relationship between mean arterial blood pressure (MAP) and hematocrit (Hct) was studied in pre- and postmenopause women in the city of Durango, Mexico. Premenopause women show a negative trend between parameters that is not statistically significant. MAP and Hct are directly related in postmenopause women (p < 0.01). It is proposed that that this MAP/Hct relationship is in part due to differences in endothelial function where menopause decreases the capacity of the endothelium to respond to increased blood viscosity and shears stress, leading to the increased production of vasodilator mediators to compensate for changes in blood viscosity due to changes in Hct. Comparison with a large group of postmenopause women in the city of Stockholm showed identical trends.
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Affiliation(s)
- Beatriz Y Salazar Vázquez
- Department of Bioengineering, University of California, San Diego, 9500 Gilman Dr, La Jolla, CA 92037-0412, USA.
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32
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Gladwin MT, Patel RP. The Role of Red Blood Cells and Hemoglobin–Nitric Oxide Interactions on Blood Flow. Am J Respir Cell Mol Biol 2008; 38:125-6. [DOI: 10.1165/rcmb.2007-0006ed] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
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