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Vali P, Lesneski A, Hardie M, Alhassen Z, Chen P, Joudi H, Sankaran D, Lakshminrusimha S. Continuous chest compressions with asynchronous ventilations increase carotid blood flow in the perinatal asphyxiated lamb model. Pediatr Res 2021; 90:752-758. [PMID: 33469187 PMCID: PMC8286977 DOI: 10.1038/s41390-020-01306-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 11/10/2020] [Accepted: 11/13/2020] [Indexed: 01/30/2023]
Abstract
BACKGROUND The neonatal resuscitation program (NRP) recommends interrupted chest compressions (CCs) with ventilation in the severely bradycardic neonate. The conventional 3:1 compression-to-ventilation (C:V) resuscitation provides 90 CCs/min, significantly lower than the intrinsic newborn heart rate (120-160 beats/min). Continuous CC with asynchronous ventilation (CCCaV) may improve the success of return of spontaneous circulation (ROSC). METHODS Twenty-two near-term fetal lambs were randomized to interrupted 3:1 C:V (90 CCs + 30 breaths/min) or CCCaV (120 CCs + 30 breaths/min). Asphyxiation was induced by cord occlusion. After 5 min of asystole, resuscitation began following NRP guidelines. The first dose of epinephrine was given at 6 min. Invasive arterial blood pressure and left carotid blood flow were continuously measured. Serial arterial blood gases were collected. RESULTS Baseline characteristics between groups were similar. Rate of and time to ROSC was similar between groups. CCCaV was associated with a higher PaO2 (partial oxygen tension) (22 ± 5.3 vs. 15 ± 3.5 mmHg, p < 0.01), greater left carotid blood flow (7.5 ± 3.1 vs. 4.3 ± 2.6 mL/kg/min, p < 0.01) and oxygen delivery (0.40 ± 0.15 vs. 0.13 ± 0.07 mL O2/kg/min, p < 0.01) compared to 3:1 C:V. CONCLUSIONS In a perinatal asphyxiated cardiac arrest lamb model, CCCaV showed greater carotid blood flow and cerebral oxygen delivery compared to 3:1 C:V resuscitation. IMPACT In a perinatal asphyxiated cardiac arrest lamb model, CCCaV improved carotid blood flow and oxygen delivery to the brain compared to the conventional 3:1 C:V resuscitation. Pre-clinical studies assessing neurodevelopmental outcomes and tissue injury comparing continuous uninterrupted chest compressions to the current recommended 3:1 C:V during newborn resuscitation are warranted prior to clinical trials.
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Affiliation(s)
- Payam Vali
- Department of Pediatrics, University of California Davis, Sacramento, CA, USA.
| | - Amy Lesneski
- Department of Pediatrics, University of California Davis, Sacramento, CA
| | - Morgan Hardie
- Department of Pediatrics, University of California Davis, Sacramento, CA
| | - Ziad Alhassen
- Department of Pediatrics, University of California Davis, Sacramento, CA
| | - Peggy Chen
- Department of Pediatrics, University of California Davis, Sacramento, CA
| | - Houssam Joudi
- Department of Pediatrics, University of California Davis, Sacramento, CA
| | - Deepika Sankaran
- Department of Pediatrics, University of California Davis, Sacramento, CA
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Moraga FA, Reyes RV, Ebensperger G, López V, Llanos AJ. Enhanced Vasoconstriction Mediated by α 1-Adrenergic Mechanisms in Small Femoral Arteries in Newborn Llama and Sheep Gestated at Low and High Altitudes. Front Physiol 2021; 12:697211. [PMID: 34421636 PMCID: PMC8371382 DOI: 10.3389/fphys.2021.697211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Accepted: 06/28/2021] [Indexed: 12/01/2022] Open
Abstract
The authors previously demonstrated that newborn llama (NBLL) express high levels of α1 adrenergic receptors, which provide a potent vasoconstriction response when compared with newborn sheep (NBSH) gestated at sea level. However, data regarding the impact of chronic gestational hypobaric hypoxia on α-adrenergic vasoconstriction in the neonatal life has not been studied. We evaluated if gestation under chronic hypobaric hypoxia modifies α1-adrenergic vasoconstrictor function in NBLL and NBSH. We compared the vasoconstrictor response induced by potassium and α-adrenergic stimuli in isolated small femoral arteries of NBLL and NBSH gestated at high altitude (HA; 3,600 m) or low altitude (LA; 580 m). The maximal contraction (RMAX) and potency (EC50) to potassium, noradrenaline (NA), and phenylephrine (PHE) were larger in HA-NBLL than LA-NBLL. RMAX to potassium, NA, and PHE were lower in HA-NBSH when compared with LA-NBSH and potency results were similar. Competitive blockade with prazosin showed that RNLL LA/HA have a similar pA2. In contrast, NBSH had increased pA2 values in HA when compared with LA. Finally, small femoral arteries denudated or treated with LNAME in LA and HA lacked NO or endothelium participation in response to PHE stimulation. In contrast, NBSH displayed that denudation or blockade with LNAME support NO or endothelium participation in response to PHE activation. In conclusion, HA chronic hypoxia enhances α1 adrenergic receptor activity in small femoral arteries in NBLL to a higher degree than NBSH, implying a higher vasoconstriction function.
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Affiliation(s)
- Fernando A Moraga
- Laboratorio de Fisiología, Hipoxia y Función Vascular, Departamento de Ciencias Biomédicas, Facultad de Medicina, Universidad Católica del Norte, Coquimbo, Chile
| | - Roberto V Reyes
- Laboratorio de Fisiología y Fisiopatología del Desarrollo, Programa de Fisiopatología, ICBM, Facultad de Medicina, Universidad de Chile, Santiago, Chile.,Centro Internacional de Estudios Andinos (INCAS), Universidad de Chile, Santiago, Chile
| | - Germán Ebensperger
- Laboratorio de Fisiología y Fisiopatología del Desarrollo, Programa de Fisiopatología, ICBM, Facultad de Medicina, Universidad de Chile, Santiago, Chile.,Centro Internacional de Estudios Andinos (INCAS), Universidad de Chile, Santiago, Chile
| | - Vasthi López
- Laboratorio de Fisiología, Hipoxia y Función Vascular, Departamento de Ciencias Biomédicas, Facultad de Medicina, Universidad Católica del Norte, Coquimbo, Chile
| | - Aníbal J Llanos
- Laboratorio de Fisiología y Fisiopatología del Desarrollo, Programa de Fisiopatología, ICBM, Facultad de Medicina, Universidad de Chile, Santiago, Chile.,Centro Internacional de Estudios Andinos (INCAS), Universidad de Chile, Santiago, Chile
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Reyes RV, Herrera EA, Ebensperger G, Sanhueza EM, Giussani DA, Llanos AJ. Perinatal cardiopulmonary adaptation to the thin air of the Alto Andino by a native Altiplano dweller, the llama. J Appl Physiol (1985) 2020; 129:152-161. [PMID: 32584666 DOI: 10.1152/japplphysiol.00800.2019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Most mammals have a poor tolerance to hypoxia, and prolonged O2 restriction can lead to organ injury, particularly during fetal and early postnatal life. Nevertheless, the llama (Lama Glama) has evolved efficient mechanisms to adapt to acute and chronic perinatal hypoxia. One striking adaptation is the marked peripheral vasoconstriction measured in the llama fetus in response to acute hypoxia, which allows efficient redistribution of cardiac output toward the fetal heart and adrenal glands. This strong peripheral vasoconstrictor tone is triggered by a carotid body reflex and critically depends on α-adrenergic signaling. A second adaptation is the ability of the llama fetus to protect its brain against hypoxic damage. During hypoxia, in the llama fetus there is no significant increase in brain blood flow. Instead, there is a fall in brain O2 consumption and temperature, together with a decrease of Na+-K+-ATPase activity and Na+ channels expression, protecting against seizures and neuronal death. Finally, the newborn llama does not develop pulmonary hypertension in response to chronic hypoxia. In addition to maintaining basal pulmonary arterial pressure at normal levels the pulmonary arterial pressor response to acute hypoxia is lower in highland than in lowland llamas. The protection against hypoxic pulmonary arterial hypertension and pulmonary contractile hyperreactivity is partly due to increased hemoxygenase-carbon monoxide signaling and decreased Ca2+ sensitization in the newborn llama pulmonary vasculature. These three striking physiological adaptations of the llama allow this species to live and thrive under the chronic influence of the hypobaric hypoxia of life at high altitude.
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Affiliation(s)
- R V Reyes
- Programa de Fisiopatología, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile.,International Center for Andean Studies (INCAS), Universidad de Chile, Santiago, Chile
| | - E A Herrera
- Programa de Fisiopatología, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile.,International Center for Andean Studies (INCAS), Universidad de Chile, Santiago, Chile
| | - G Ebensperger
- Programa de Fisiopatología, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile.,International Center for Andean Studies (INCAS), Universidad de Chile, Santiago, Chile
| | - E M Sanhueza
- Programa de Fisiopatología, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - D A Giussani
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom
| | - A J Llanos
- Programa de Fisiopatología, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile.,International Center for Andean Studies (INCAS), Universidad de Chile, Santiago, Chile
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Reyes RV, Díaz M, Ebensperger G, Herrera EA, Quezada SA, Hernandez I, Sanhueza EM, Parer JT, Giussani DA, Llanos AJ. The role of nitric oxide in the cardiopulmonary response to hypoxia in highland and lowland newborn llamas. J Physiol 2018; 596:5907-5923. [PMID: 29369354 PMCID: PMC6265547 DOI: 10.1113/jp274340] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Accepted: 01/17/2018] [Indexed: 01/19/2023] Open
Abstract
KEY POINTS Perinatal hypoxia causes pulmonary hypertension in neonates, including humans. However, in species adapted to hypoxia, such as the llama, there is protection against pulmonary hypertension. Nitric oxide (NO) is a vasodilatator with an established role in the cardiopulmonary system of many species, but its function in the hypoxic pulmonary vasoconstrictor response in the newborn llama is unknown. Therefore, we studied the role of NO in the cardiopulmonary responses to acute hypoxia in high- and lowland newborn llamas. We show that high- compared to lowland newborn llamas have a reduced pulmonary vasoconstrictor response to acute hypoxia. Protection against excessive pulmonary vasoconstriction in the highland llama is mediated via enhancement of NO pathways, including increased MYPT1 and reduced ROCK expression as well as Ca2+ desensitization. Blunting of pulmonary hypertensive responses to hypoxia through enhanced NO pathways may be an adaptive mechanism to withstand life at high altitude in the newborn llama. ABSTRACT Llamas are born in the Alto Andino with protection against pulmonary hypertension. The physiology underlying protection against pulmonary vasoconstrictor responses to acute hypoxia in highland species is unknown. We determined the role of nitric oxide (NO) in the cardiopulmonary responses to acute hypoxia in high- and lowland newborn llamas. The cardiopulmonary function of newborn llamas born at low (580 m) or high altitude (3600 m) was studied under acute hypoxia, with and without NO blockade. In pulmonary arteries, we measured the reactivity to potassium and sodium nitroprusside (SNP), and in lung we determined the content of cGMP and the expression of the NO-related proteins: BKCa, PDE5, PSer92-PDE5, PKG-1, ROCK1 and 2, MYPT1, PSer695-MYPT1, PThr696-MYPT1, MLC20 and PSer19-MLC20. Pulmonary vascular remodelling was evaluated by morphometry and based on α-actin expression. High- compared to lowland newborn llamas showed lower in vivo pulmonary arterial pressor responses to acute hypoxia. This protection involved enhanced NO function, as NO blockade reverted the effect and the pulmonary arterial dilatator response to SNP was significantly enhanced in highland neonates. The pulmonary expression of ROCK2 and the phosphorylation of MLC20 were lower in high-altitude llamas. Conversely, MYPT1 was up-regulated whilst PSer695-MYPT1 and PThr695-MYPT1 did not change. Enhanced NO-dependent mechanisms were insufficient to prevent pulmonary arterial remodelling. Combined, the data strongly support that in the highland newborn llama reduced ROCK, increased MYPT1 expression and Ca2+ desensitization in pulmonary tissue allow an enhanced NO biology to limit hypoxic pulmonary constrictor responses. Blunting of hypoxic pulmonary hypertensive responses may be an adaptive mechanism to life at high altitude.
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Affiliation(s)
- Roberto V. Reyes
- Laboratorio de Bioquímica y Biología Molecular de la Hipoxia, Programa de Fisiopatología, Instituto de Ciencias Biomédicas, Facultad de MedicinaUniversidad de ChileSantiagoChile
- International Center for Andean Studies (INCAS)Universidad de ChileSantiagoChile
| | - Marcela Díaz
- Departamento de Promoción de la Salud de la Mujer y el Recién Nacido, Facultad de MedicinaUniversidad de ChileSantiagoChile
- Laboratorio de Mecanismos de Stress y Adaptación Vascular, Programa de Fisiopatología, Instituto de Ciencias Biomédicas, Facultad de MedicinaUniversidad de ChileSantiagoChile
| | - Germán Ebensperger
- Laboratorio de Mecanismos de Stress y Adaptación Vascular, Programa de Fisiopatología, Instituto de Ciencias Biomédicas, Facultad de MedicinaUniversidad de ChileSantiagoChile
| | - Emilio A. Herrera
- International Center for Andean Studies (INCAS)Universidad de ChileSantiagoChile
- Laboratorio de Función y Reactividad Vascular, Programa de Fisiopatología, Instituto de Ciencias Biomédicas, Facultad de MedicinaUniversidad de ChileSantiagoChile
| | - Sebastián A. Quezada
- Laboratorio de Bioquímica y Biología Molecular de la Hipoxia, Programa de Fisiopatología, Instituto de Ciencias Biomédicas, Facultad de MedicinaUniversidad de ChileSantiagoChile
| | - Ismael Hernandez
- Laboratorio de Bioquímica y Biología Molecular de la Hipoxia, Programa de Fisiopatología, Instituto de Ciencias Biomédicas, Facultad de MedicinaUniversidad de ChileSantiagoChile
| | - Emilia M. Sanhueza
- Laboratorio de Fisiología y Fisiopatología del Desarrollo, Programa de Fisiopatología, Instituto de Ciencias Biomédicas, Facultad de MedicinaUniversidad de ChileSantiagoChile
| | - Julian T. Parer
- Department of Obstetrics, Gynecology and Reproductive SciencesUniversity of California San FranciscoCaliforniaUSA
| | - Dino A. Giussani
- Department of Physiology, Development and NeuroscienceUniversity of CambridgeUK
| | - Aníbal J. Llanos
- International Center for Andean Studies (INCAS)Universidad de ChileSantiagoChile
- Laboratorio de Fisiología y Fisiopatología del Desarrollo, Programa de Fisiopatología, Instituto de Ciencias Biomédicas, Facultad de MedicinaUniversidad de ChileSantiagoChile
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López V, Moraga FA, Llanos AJ, Ebensperger G, Taborda MI, Uribe E. Plasmatic Concentrations of ADMA and Homocystein in Llama ( Lama glama) and Regulation of Arginase Type II: An Animal Resistent to the Development of Pulmonary Hypertension Induced by Hypoxia. Front Physiol 2018; 9:606. [PMID: 29896110 PMCID: PMC5986928 DOI: 10.3389/fphys.2018.00606] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2017] [Accepted: 05/04/2018] [Indexed: 12/21/2022] Open
Abstract
There are animal species that have adapted to life at high altitude and hypobaric hypoxia conditions in the Andean highlands. One such species is the llama (Lama glama), which seem to have developed efficient protective mechanisms to avoid maladaptation resulting from chronic hypoxia, such as a resistance to the development of hypoxia -induced pulmonary hypertension. On the other hand, it is widely known that different models of hypertension can arise as a result of changes in endothelial function. The respect, one of the common causes of deregulation in endothelial vasodilator function have been associated with down-regulation of the NO synthesis and an increase in plasma levels of asymmetric dimethylarginine (ADMA) and homocysteine. Additionally, it is also known that NO production can be regulated by plasma levels of L-arginine as a result of the competition between nitric oxide synthase (NOS) and arginase. The objective of this study, was to determine the baseline concentrations of ADMA and homocysteine in llama, and to evaluate their effect on the arginase pathway and their involvement in the resistance to the development of altitude-induced pulmonary hypertension. METHOD Lowland and highland newborn sheep and llama were investigated near sea level and at high altitude. Blood determinations of arterial blood gases, ADMA and homocysteíne are made and the effect of these on the arginase activity was evaluated. RESULTS The basal concentrations of ADMA and homocysteine were determined in llama, and they were found to be significantly lower than those found in other species and in addition, the exposure to hypoxia is unable to increase its concentration. On the other hand, it was observed that the llama exhibited 10 times less arginase II activity as compared to sheep, and the expression was not induced by hypoxia. Finally, ADMA y Hcy, has no effect on the type II arginase pathway. CONCLUSION Based on our results, we propose that low concentrations of ADMA and homocysteine found in llamas, the low expression of arginase type II, DDAH-2 and CBS, as well as its insensitivity to activation by homocysteine could constitute an adaptation mechanism of these animals to the hypoxia.
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Affiliation(s)
- Vasthi López
- Laboratorio de Metabolismo de Aminoácidos e Hipoxia, Departamento de Ciencias Biomédicas, Universidad Católica del Norte, Coquimbo, Chile
| | - Fernando A Moraga
- Laboratorio de Fisiología, Hipoxia y Función Vascular, Departamento de Ciencias Biomedicas, Facultad de Medicina, Universidad Católica del Norte, Coquimbo, Chile
| | - Anibal J Llanos
- Laboratorio de Fisiología y Fisiopatología del Desarrollo, Departamento de Ciencias Biomédicas, Universidad de Chile, Santiago, Chile
| | - German Ebensperger
- Laboratorio de Fisiología y Fisiopatología del Desarrollo, Departamento de Ciencias Biomédicas, Universidad de Chile, Santiago, Chile
| | - María I Taborda
- Laboratorio de Metabolismo de Aminoácidos e Hipoxia, Departamento de Ciencias Biomédicas, Universidad Católica del Norte, Coquimbo, Chile
| | - Elena Uribe
- Laboratorio de Enzimología, Departamento de Bioquímica y Biología Molecular, Universidad of Concepción, Concepción, Chile
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Bertin F, Squires J, Kritchevsky J, Taylor S. Clinical findings and survival in 56 sick neonatal New World camelids. J Vet Intern Med 2015; 29:368-74. [PMID: 25319312 PMCID: PMC4858106 DOI: 10.1111/jvim.12478] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Revised: 08/11/2014] [Accepted: 09/08/2014] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND Information pertaining to clinical presentation and outcome of neonatal New World camelids (NWC) is limited when compared to calves and foals. HYPOTHESIS Values of variables at admission and subsequent treatment would predict survival in sick neonatal NWC. ANIMALS Fifty-six client-owned sick neonatal NWC presented over a 10-year period to the Purdue University Veterinary Teaching Hospital. METHODS A retrospective study was performed. Inclusion criteria were NWC less than 30 days of age with complete medical records that presented between 2000 and 2010. RESULTS The median age at presentation was 1 day (range 1-20). The most common diagnoses were systemic inflammatory response syndrome (50%), congenital defects (41%), ophthalmic lesions (21%), sepsis (16%), and gastrointestinal diseases (16%). Sixty-six percent of NWC survived to discharge. Clinicopathologic findings on admission were variable and not specific for disorders. Factors associated with survival were absence of choanal atresia (P = .001, OR: 55.9 [2.5-1,232]), administration of llama plasma (P = .013, OR: 4.9 [1.4-17.7]), and antimicrobial treatment with trimethoprim-sulfamethoxazole (TMS) (P = .016, OR: 6.5 [1.3-32.2]). CONCLUSIONS AND CLINICAL IMPORTANCE The use of antibiotics, particularly TMS, and llama plasma are recommended in sick neonatal NWC. Results from this study could contribute toward defining a NWC-specific sepsis scoring system.
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Affiliation(s)
- F.R. Bertin
- Department of Veterinary Clinical SciencesCollege of Veterinary MedicinePurdue UniversityWest LafayetteIN
- Present address: 3999, chemin de la Côte Sainte‐CatherineMontréalQC
| | - J.M. Squires
- Department of Veterinary Clinical SciencesCollege of Veterinary MedicinePurdue UniversityWest LafayetteIN
| | - J.E. Kritchevsky
- Department of Veterinary Clinical SciencesCollege of Veterinary MedicinePurdue UniversityWest LafayetteIN
| | - S.D. Taylor
- Department of Veterinary Clinical SciencesCollege of Veterinary MedicinePurdue UniversityWest LafayetteIN
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Modulating hemoglobin nitrite reductase activity through allostery: a mathematical model. Nitric Oxide 2013; 35:193-8. [PMID: 24177061 DOI: 10.1016/j.niox.2013.10.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2013] [Revised: 10/15/2013] [Accepted: 10/19/2013] [Indexed: 11/23/2022]
Abstract
The production of nitric oxide by hemoglobin (Hb) has been proposed to play a major role in the control of blood flow. Because of the allosteric nature of hemoglobin, the nitrite reductase activity is a complex function of oxygen partial pressure PO2. We have previous developed a model to obtain the micro rate constants for nitrite reduction by R state (kR) and T state (kT) hemoglobin in terms of the experimental maximal macro rate constant kNmax and the corresponding oxygen concentration PO2max. However, because of the intrinsic difficulty in obtaining accurate macro rate constant kN, from available experiments, we have developed an alternative method to determine the micro reaction rate constants (kR and kT) by fitting the simulated macro reaction rate curve (kN versus PO2) to the experimental data. We then use our model to analyze the effect of pH (Bohr Effect) and blood ageing on the nitrite reductase activity, showing that the fall of bisphosphoglycerate (BPG) during red cell storage leads to increase NO production. Our model can have useful predictive and explanatory power. For example, the previously described enhanced nitrite reductase activity of ovine fetal Hb, in comparison to the adult protein, may be understood in terms of a weaker interaction with BPG and an increase in the value of kT from 0.0087M(-1)s(-1) to 0.083M(-1)s(-1).
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Liu C, Zhang L, Li N. The specific expression pattern of globin mRNAs in Tibetan chicken during late embryonic stage under hypoxia. Comp Biochem Physiol A Mol Integr Physiol 2013; 164:638-44. [DOI: 10.1016/j.cbpa.2012.09.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Revised: 09/02/2012] [Accepted: 09/04/2012] [Indexed: 11/16/2022]
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Llanos AJ, Ebensperger G, Herrera EA, Reyes RV, Moraga FA, Parer JT, Giussani DA. Counterpoint: high altitude is not for the birds! J Appl Physiol (1985) 2012; 111:1515-8. [PMID: 22096208 DOI: 10.1152/japplphysiol.00821.2011a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Affiliation(s)
- Aníbal J Llanos
- Laboratorio de Fisiología y Fisiopatología del Desarrollo Programa de Fisiopatología Instituto de Ciencias Biomédicas (ICBM)Facultad de Medicina, Chile
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11
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Soegaard LB, Hansen MN, van Elk C, Brahm J, Jensen FB. Respiratory properties of blood in the harbor porpoise, Phocoena phocoena. J Exp Biol 2012; 215:1938-43. [DOI: 10.1242/jeb.069872] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARY
Harbor porpoises are active divers that exchange O2 and CO2 with the environment during a fast single breath upon surfacing. We investigated blood O2-transporting properties, buffer characteristics, Cl– transport via the erythrocyte anion exchanger (AE1), circulating nitric oxide metabolites and hemoglobin nitrite reduction in harbor porpoises with the aim to evaluate traits that are adaptive for diving behavior. Blood O2 affinity was higher in harbor porpoises than in similar sized terrestrial mammals, as supported by our parallel recordings of O2 equilibria in sheep and pig blood. Further, O2 affinity tended to increase with increasing body mass. A high O2 affinity favors O2 extraction from the lungs, but a normal Bohr effect (ΔlogP50/ΔpH=–0.46) gradually lowers O2 affinity during dives (where CO2 accumulates) to assist O2 off-loading to perfused tissues. The true plasma non-bicarbonate buffer value was moderately higher than in terrestrial mammals and increased upon deoxygenation. Plasma bicarbonate was also relatively high, contributing to increase the overall buffer capacity. The apparent Cl– permeability of harbor porpoise erythrocytes was similar to the human value at 37°C, showing absence of a comparative increase in the velocity of erythrocyte HCO –3/Cl– exchange to aid CO2 excretion. The Q10 for AE1-mediated Cl– transport in harbor porpoises was lower than in humans and seemed to match the Q10 for metabolism (Q10≈2). Plasma nitrite, plasma nitrate and hemoglobin-mediated nitrite reduction were elevated compared with mammalian standards, suggesting that increased nitric oxide bioavailability and nitrite-derived nitric oxide could play important roles in diving physiology.
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Affiliation(s)
- Lisette B. Soegaard
- Institute of Biology, University of Southern Denmark, DK-5230 Odense M, Denmark
- Fjord and Belt, DK-5300 Kerteminde, Denmark
| | - Marie N. Hansen
- Institute of Biology, University of Southern Denmark, DK-5230 Odense M, Denmark
| | | | - Jesper Brahm
- Department of Cellular and Molecular Medicine, University of Copenhagen, Denmark
| | - Frank B. Jensen
- Institute of Biology, University of Southern Denmark, DK-5230 Odense M, Denmark
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Rebuttal from Llanos et al. J Appl Physiol (1985) 2011; 111:1518-9. [PMID: 22096210 DOI: 10.1152/japplphysiol.00821.2011c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Moraga FA, Reyes RV, Herrera EA, Riquelme RA, Ebensperger G, Pulgar VM, Parer JT, Giussani DA, Llanos AJ. Role of the α-adrenergic system in femoral vascular reactivity in neonatal llamas and sheep: a comparative study between highland and lowland species. Am J Physiol Regul Integr Comp Physiol 2011; 301:R1153-60. [PMID: 21795632 PMCID: PMC3197338 DOI: 10.1152/ajpregu.00124.2010] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Using an integrative approach at the whole animal, isolated vessels, and molecular levels, we tested the hypothesis that the llama, a species that undergoes pregnancy under the influence of the chronic hypoxia of high altitude, delivers offspring with an increased α-adrenergic peripheral vascular reactivity compared with neonates from lowland species. We studied the femoral vascular response to acute hypoxia in vivo, the reactivity of femoral vessels ex vivo, and the expression of femoral α1-adrenergic receptor subtypes using RT-PCR in vitro. The increase in femoral resistance during hypoxia was 3.6 times greater in newborn llamas than newborn sheep (P < 0.05). The sensitivity of the contractile response to noradrenaline (pD2 = 5.18 ± 0.06 vs. 4.84 ± 0.05, P < 0.05) and the maximal response (Rmax = 101.3 ± 1.4 vs. 52.4 ± 1.4% K+max, P < 0.05) and sensitivity (pD2 = 5.47 ± 0.03 vs. 4.57 ± 0.05, P < 0.05) to phenylephrine were higher in femoral vessels from newborn llamas than newborn sheep. Competitive inhibition with prazosin of noradrenaline-induced contraction followed by Schild analysis showed higher affinity in the llama than the sheep (pA2 = 10.08 ± 0.093 vs. 8.98 ± 0.263, respectively, P < 0.05), consistent with greater α1B-adrenergic receptor transcript expression observed in small femoral arteries from neonatal llama. The llama newborn demonstrates significantly greater α-adrenergic peripheral vascular reactivity compared with neonates from lowland species that could be partially explained by preferential expression of α1B-adrenergic receptor subtype.
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Affiliation(s)
- Fernando A Moraga
- Laboratorio de Fisiología y Fisiopatología del Desarrollo, Programa de Fisiopatología, ICBM, Facultad de Medicina, Universidad de Chile, Santiago, Chile
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14
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Kwon YM, Chung HS, Moon C, Yockman J, Park YJ, Gitlin SD, David AE, Yang VC. L-Asparaginase encapsulated intact erythrocytes for treatment of acute lymphoblastic leukemia (ALL). J Control Release 2009; 139:182-9. [PMID: 19577600 DOI: 10.1016/j.jconrel.2009.06.027] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2009] [Revised: 06/01/2009] [Accepted: 06/26/2009] [Indexed: 10/20/2022]
Abstract
As a primary drug for the treatment of acute lymphoblastic leukemia (ALL), encapsulation of L-asparaginase (ASNase) into red blood cells (RBC) has been popular to circumvent immunogenicity from the exogenous protein. Unlike existing methods that perturbs RBC membranes, we introduce a novel method of RBC-incorporation of proteins using the membrane-translocating low molecular weight protamine (LMWP). Confocal study of fluorescence-labeled LMWP-ovalbumin, as a model protein conjugate, has shown significant fluorescence inside RBCs. Surface morphology by scanning electron microscopy of the RBCs loaded with LMWP-ASNase was indistinguishable with normal RBCs. These drug loaded RBCs also closely resembled the profile of the native erythrocytes in terms of osmotic fragility, oxygen dissociation and hematological parameters. The in vivo half-life of enzyme activity after administering 8 units of RBC/LMWP-ASNase in DBA/2 mice was prolonged to 4.5+/-0.5 days whereas that of RBCs loaded with ASNase via a hypotonic method was 2.4+/-0.7 days. Furthermore, the mean survival time of DBA/2 mice bearing mouse lymphoma cell L5178Y was improved by approximately 44% compared to the saline control group after treatment with the RBC loaded enzymes. From these data, an innovative, novel method for encapsulating proteins into intact and fully functional erythrocytes was established for potential treatment of ALL.
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Affiliation(s)
- Young Min Kwon
- Tianjin Key Laboratory for Modern Drug Delivery and High Efficiency, Tianjin University, Tianjin 300072, China
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15
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16
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Zhang X, Liu C, Yuan Y, Shan X, Sheng Y, Xu F. A noninvasive method for measuring the oxygen binding-releasing capacity of hemoglobin-loaded polymeric nanoparticles as oxygen carrier. JOURNAL OF MATERIALS SCIENCE. MATERIALS IN MEDICINE 2009; 20:1025-1030. [PMID: 19199110 DOI: 10.1007/s10856-008-3676-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2008] [Accepted: 12/16/2008] [Indexed: 05/27/2023]
Abstract
Based on the strong penetration capacity of near infrared lights (NIRs) and different absorption of oxyhemoglobin and deoxyhemoglobin in NIRs region, a novel noninvasive method, with the aid of an airproof-equilibrium apparatus, was developed to determine the oxygen binding-releasing capacity, including oxygen dissociation curve (ODC) and P(50), of the hemoglobin-loaded polymeric nanoparticles (HbP) in this study. The measured ODC of the PLA-PEG HbP was very close to that of the native hemoglobin, and the corresponding P(50) (26.1 mmHg) was also near to the native precursor protein (27.3 mmHg), indicative of the validity of the method proposed. To further verify the method proposed, the oxygen binding-releasing capacity of the HbPs prepared by PCL, PCL-PEG, PLA were also investigated with human blood as control. These results indicated that the method developed here enabled accurate and noninvasive determination of the oxygen binding-releasing capacity of the biodegradable polymeric oxygen carriers.
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Affiliation(s)
- Xiaolan Zhang
- Key Laboratory for Ultrafine Materials of Ministry of Education, Engineering Research Center for Biomedical Materials of Ministry of Education, East China University of Science and Technology, Shanghai, People's Republic of China.
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17
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Llanos AJ, Riquelme RA, Herrera EA, Ebensperger G, Krause B, Reyes RV, Sanhueza EM, Pulgar VM, Behn C, Cabello G, Parer JT, Giussani DA, Blanco CE, Hanson MA. Evolving in thin air—Lessons from the llama fetus in the altiplano. Respir Physiol Neurobiol 2007; 158:298-306. [PMID: 17588504 DOI: 10.1016/j.resp.2007.04.012] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2007] [Revised: 04/24/2007] [Accepted: 04/26/2007] [Indexed: 11/22/2022]
Abstract
Compared with lowland species, fetal life for mammalian species whose mothers live in high altitude is demanding. For instance, fetal llamas have to cope with the low fetal arterial PO2 of all species, but also the likely superimposition of hypoxia as a result of the decreased oxygen environment in which the mother lives in the Andean altiplano. When subjected to acute hypoxia the llama fetus responds with an intense peripheral vasoconstriction mediated by alpha-adrenergic mechanisms plus high plasma concentrations of catecholamines and neuropeptide Y (NPY). Endothelial factors such as NO and endothelin-1 also play a role in the regulation of local blood flows. Unlike fetuses of lowland species such as the sheep, the llama fetus shows a profound cerebral hypometabolic response to hypoxia, decreasing cerebral oxygen consumption, Na-K-ATPase activity and temperature, and resulting in an absence of seizures and apoptosis in neural cells. These strategies may have evolved to prevent hypoxic injury to the brain or other organs in the face of the persistent hypobaric hypoxia of life in the Andean altiplano.
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Affiliation(s)
- Aníbal J Llanos
- Laboratorio de Fisiología y Fisiopatología del Desarrollo, Programa de Fisiopatología, Instituto de Ciencias Biomédicas (ICBM), Facultad de Medicina, Universidad de Chile, Santiago, Chile.
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18
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Weber RE. High-altitude adaptations in vertebrate hemoglobins. Respir Physiol Neurobiol 2007; 158:132-42. [PMID: 17561448 DOI: 10.1016/j.resp.2007.05.001] [Citation(s) in RCA: 124] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2007] [Revised: 05/01/2007] [Accepted: 05/01/2007] [Indexed: 11/25/2022]
Abstract
Vertebrates at high altitude are subjected to hypoxic conditions that challenge aerobic metabolism. O(2) transport from the respiratory surfaces to tissues requires matching between the O(2) loading and unloading tensions and the O(2)-affinity of blood, which is an integrated function of hemoglobin's intrinsic O(2)-affinity and its allosteric interaction with cellular effectors (organic phosphates, protons and chloride). Whereas short-term altitudinal adaptations predominantly involve adjustments in allosteric interactions, long-term, genetically-coded adaptations typically involve changes in the structure of the haemoglobin molecules. The latter commonly comprise substitutions of amino acid residues at the effector binding sites, the heme-protein contacts, or at intersubunit contacts that stabilize either the low-affinity ('Tense') or the high-affinity ('Relaxed') structures of the molecules. Molecular heterogeneity (multiple isoHbs with differentiated oxygenation properties) can further broaden the range of physico-chemical conditions where Hb functions under altitudinal hypoxia. This treatise reviews the molecular and cellular mechanisms that adapt haemoglobin-oxygen affinities in mammals, birds and ectothermic vertebrates at high altitude.
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Affiliation(s)
- Roy E Weber
- Zoophysiology, Institute of Biological Sciences, Building 1131, University of Aarhus, DK 8000 Aarhus, Denmark.
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Ebensperger G, Ebensperger R, Herrera EA, Riquelme RA, Sanhueza EM, Lesage F, Marengo JJ, Tejo RI, Llanos AJ, Reyes RV. Fetal brain hypometabolism during prolonged hypoxaemia in the llama. J Physiol 2005; 567:963-75. [PMID: 16037083 PMCID: PMC1474220 DOI: 10.1113/jphysiol.2005.094524] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
In this study we looked for additional evidence to support the hypothesis that fetal llama reacts to hypoxaemia with adaptive brain hypometabolism. We determined fetal llama brain temperature, Na(+) and K(+) channel density and Na(+)-K(+)-ATPase activity. Additionally, we looked to see whether there were signs of cell death in the brain cortex of llama fetuses submitted to prolonged hypoxaemia. Ten fetal llamas were instrumented under general anaesthesia to measure pH, arterial blood gases, mean arterial pressure, heart rate, and brain and core temperatures. Measurements were made 1 h before and every hour during 24 h of hypoxaemia (n = 5), which was imposed by reducing maternal inspired oxygen fraction to reach a fetal arterial partial pressure of oxygen (P(a,O(2))) of about 12 mmHg. A normoxaemic group was the control (n = 5). After 24 h of hypoxaemia, we determined brain cortex Na(+)-K(+)-ATPase activity, ouabain binding, and the expression of NaV1.1, NaV1.2, NaV1.3, NaV1.6, TREK1, TRAAK and K(ATP) channels. The lack of brain cortex damage was assessed as poly ADP-ribose polymerase (PARP) proteolysis. We found a mean decrease of 0.56 degrees C in brain cortex temperature during prolonged hypoxaemia, which was accompanied by a 51% decrease in brain cortex Na(+)-K(+)-ATPase activity, and by a 44% decrease in protein content of NaV1.1, a voltage-gated Na(+) channel. These changes occurred in absence of changes in PARP protein degradation, suggesting that the cell death of the brain was not enhanced in the fetal llama during hypoxaemia. Taken together, these results provide further evidence to support the hypothesis that the fetal llama responds to prolonged hypoxaemia with adaptive brain hypometabolism, partly mediated by decreases in Na(+)-K(+)-ATPase activity and expression of NaV channels.
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Affiliation(s)
- Germán Ebensperger
- Programa de Fisiopatología, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago
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Yilmaz C, Hogg DC, Ravikumar P, Hsia CCW. Ventilatory acclimatization in awake guinea pigs raised at high altitude. Respir Physiol Neurobiol 2005; 145:235-42. [PMID: 15705538 DOI: 10.1016/j.resp.2004.07.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/20/2004] [Indexed: 11/17/2022]
Abstract
To determine if laboratory strains of guinea pigs bred at sea level (SL) are "pre-adapted" to high altitude (HA), we raised litter-matched weanling Hartley guinea pigs for 4 months at SL, intermediate altitude (IA, 1250 m) or HA (3800 m) and exposed them acutely to 100, 21 and 12% inspired O2 at their respective altitude of residence. Control animals raised at SL were also exposed acutely to 10 and 8% inspired O2. In awake spontaneously breathing guinea pigs raised at SL, resting minute ventilation and tidal volume increased significantly when inspired O2 tension fell below about 60 mm Hg. In guinea pigs raised at IA or HA, ventilation was higher at any given inspired O2 tension in direct relationship to the altitude of residence. Resting hematocrit was also higher in animals raised at HA than at SL. We conclude that the pattern of ventilatory acclimatization to HA exposure in Hartley guinea pigs is similar to that in laboratory rats and human lowlanders; therefore laboratory guinea pigs are not pre-adapted and are suitable animals for the study of adaptation to high altitude.
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Affiliation(s)
- Cuneyt Yilmaz
- Department of Internal Medicine, Pulmonary and Critical Care Medicine, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-9034, USA
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21
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Llanos AJ, Riquelme RA, Sanhueza EM, Hanson MA, Blanco CE, Parer JT, Herrera EA, Pulgar VM, Reyes RV, Cabello G, Giussani DA. The fetal llama versus the fetal sheep: different strategies to withstand hypoxia. High Alt Med Biol 2003; 4:193-202. [PMID: 12855051 DOI: 10.1089/152702903322022794] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The pregnant llama (Lama glama) has walked for millions of years through the thin oxygen trail of the Andean altiplano. We hypothesize that a pool of genes has been selected in the llama that express efficient mechanisms to withstand this low-oxygen milieu. The llama fetus responds to acute hypoxia with an intense peripheral vasoconstriction that is not affected by bilateral section of the carotid sinus nerves. Moreover, the increase in fetal plasma concentrations of vasoconstrictor hormones, such as catecholamines, neuropeptide Y, and vasopressin, is much greater in the llama than in the sheep fetus. Furthermore, treatment of fetal llamas with an alpha-adrenergic antagonist abolished the peripheral vasoconstriction and resulted in fetal cardiovascular collapse and death during acute hypoxia, suggesting an indispensable upregulation of alpha-adrenergic mechanisms in this high altitude species. Local endothelial factors such as nitric oxide (NO) also play a key role in the regulation of fetal adrenal blood flow and in the adrenal secretion of catecholamines and cortisol. Interestingly, in contrast to the human or sheep fetus, the llama fetus showed a small increase in brain blood flow during acute hypoxia, with no increase in oxygen extraction across the brain, and thereby a decrease in brain oxygen consumption. These results suggest that the llama fetus responds to acute hypoxia with hypometabolism. How this reduction in metabolism is produced and how the cells are preserved during this condition remain to be elucidated.
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Affiliation(s)
- Aníbal J Llanos
- Laboratorio de Fisiología y Fisiopatología del Desarrollo, Programa de Fisiopatología, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile.
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22
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Riquelme RA, Sánchez G, Liberona L, Sanhueza EM, Giussani DA, Blanco CE, Hanson MA, Llanos AJ. Nitric oxide plays a role in the regulation of adrenal blood flow and adrenocorticomedullary functions in the llama fetus. J Physiol 2002; 544:267-76. [PMID: 12356897 PMCID: PMC2290576 DOI: 10.1113/jphysiol.2002.018325] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The hypothesis that nitric oxide plays a key role in the regulation of adrenal blood flow and plasma concentrations of cortisol and catecholamines under basal and hypoxaemic conditions in the llama fetus was tested. At 0.6-0.8 of gestation, 11 llama fetuses were surgically prepared for long-term recording under anaesthesia with vascular and amniotic catheters. Following recovery all fetuses underwent an experimental protocol based on 1 h of normoxaemia, 1 h of hypoxaemia and 1 h of recovery. In nine fetuses, the protocol occurred during fetal I.V. infusion with saline and in five fetuses during fetal I.V. treatment with the nitric oxide synthase inhibitor L-NAME. Adrenal blood flow was determined by the radiolabelled microsphere method during each of the experimental periods during saline infusion and treatment with L-NAME. Treatment with L-NAME during normoxaemia led to a marked fall in adrenal blood flow and a pronounced increase in plasma catecholamine concentrations, but it did not affect plasma ACTH or cortisol levels. In saline-infused fetuses, acute hypoxaemia elicited an increase in adrenal blood flow and in plasma ACTH, cortisol, adrenaline and noradrenaline concentrations. Treatment with L-NAME did not affect the increase in fetal plasma ACTH, but prevented the increments in adrenal blood flow and in plasma cortisol and adrenaline concentrations during hypoxaemia in the llama fetus. In contrast, L-NAME further enhanced the increase in fetal plasma noradrenaline. These data support the hypothesis that nitric oxide has important roles in the regulation of adrenal blood flow and adrenal corticomedullary functions during normoxaemia and hypoxaemia functions in the late gestation llama fetus.
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Affiliation(s)
- Raquel A Riquelme
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
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23
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Llanos AJ, Riquelme RA, Sanhueza EM, Herrera E, Cabello G, Giussani DA, Parer JT. Regional brain blood flow and cerebral hemispheric oxygen consumption during acute hypoxaemia in the llama fetus. J Physiol 2002; 538:975-83. [PMID: 11826180 PMCID: PMC2290086 DOI: 10.1113/jphysiol.2001.013230] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Unlike fetal animals of lowland species, the llama fetus does not increase its cerebral blood flow during an episode of acute hypoxaemia. This study tested the hypothesis that the fetal llama brain maintains cerebral hemispheric O2 consumption by increasing cerebral O2 extraction rather than decreasing cerebral oxygen utilisation during acute hypoxaemia. Six llama fetuses were surgically instrumented under general anaesthesia at 217 days of gestation (term ca 350 days) with vascular and amniotic catheters in order to carry out cardiorespiratory studies. Following a control period of 1 h, the llama fetuses underwent 3 x 20 min episodes of progressive hypoxaemia, induced by maternal inhalational hypoxia. During basal conditions and during each of the 20 min of hypoxaemia, fetal cerebral blood flow was measured with radioactive microspheres, cerebral oxygen extraction was calculated, and fetal cerebral hemispheric O2 consumption was determined by the modified Fick principle. During hypoxaemia, fetal arterial O2 tension and fetal pH decreased progressively from 24 +/- 1 to 20 +/- 1 Torr and from 7.36 +/- 0.01 to 7.33 +/- 0.01, respectively, during the first 20 min episode, to 16 +/- 1 Torr and 7.25 +/- 0.05 during the second 20 min episode and to 14 +/- 1 Torr and 7.21 +/- 0.04 during the final 20 min episode. Fetal arterial partial pressure of CO2 (P(a,CO2), 42 +/- 2 Torr) remained unaltered from baseline throughout the experiment. Fetal cerebral hemispheric blood flow and cerebral hemispheric oxygen extraction were unaltered from baseline during progressive hypoxaemia. In contrast, a progressive fall in fetal cerebral hemispheric oxygen consumption occurred during the hypoxaemic challenge. In conclusion, these data do not support the hypothesis that the fetal llama brain maintains cerebral hemispheric O2 consumption by increasing cerebral hemispheric O2 extraction. Rather, the data show that in the llama fetus, a reduction in cerebral hemispheric metabolism occurs during acute hypoxaemia.
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Affiliation(s)
- Aníbal J Llanos
- Laboratorio de Fisiología y Fisiopatología del Desarrollo, Programa de Fisiopatología, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile.
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24
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Mulder AL, van Goor CA, Giussani DA, Blanco CE. Alpha-adrenergic contribution to the cardiovascular response to acute hypoxemia in the chick embryo. Am J Physiol Regul Integr Comp Physiol 2001; 281:R2004-10. [PMID: 11705787 DOI: 10.1152/ajpregu.2001.281.6.r2004] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Fetal responses to acute hypoxemia include bradycardia, increase in blood pressure, and peripheral vasoconstriction. Peripheral vasoconstriction contributes to the redistribution of the cardiac output away from ancillary vascular beds toward myocardial, cerebral, and adrenal circulations. We investigated the effect of alpha-adrenergic receptor blockade on this fetal response. Fluorescent microspheres were used to measure cardiac output distribution during basal and hypoxemic conditions with and without phentolamine treatment. Phentolamine altered basal cardiac output distribution, indicating a basal alpha-adrenergic tone, but this was mainly noted at the earlier stages of incubation. During hypoxemia, phentolamine prevented vasoconstriction in the carcass. At day 19 of incubation, the percent cardiac output distributed to the carcass increased by 20% compared with a decrease in the control group by 17%. Phentolamine markedly attenuated the subsequent redistribution of the cardiac output toward the brain (from +102% in the control group to -25% in the phentolamine-treated group) and the heart (from +196% in the control group to +69% in the phentolamine-treated group). In the chick embryo, alpha-adrenergic mechanisms contribute to the maintenance of basal vascular tone and to the redistribution of the cardiac output away from the peripheral circulations toward the brain and heart during hypoxemic conditions.
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Affiliation(s)
- A L Mulder
- Department of Pediatrics, Maastricht University Hospital, PO Box 5800, 6202 AZ Maastricht, The Netherlands.
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25
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Gazitúa FJ, Corradini P, Ferrando G, Raggi LA, Parraguez VH. Prediction of gestational age by ultrasonic fetometry in llamas (Lama glama) and alpacas (Lama pacos). Anim Reprod Sci 2001; 66:81-92. [PMID: 11343844 DOI: 10.1016/s0378-4320(01)00083-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Fetal biparietal diameter (BPD) and thorax height (TH) were measured by ultrasound during intrauterine growth in pregnant llamas (Lama glama) and alpacas (Lama pacos). The goal was to establish representative curves that allows estimation of gestational age (GA) from real-time ultrasonic measurements of these fetal structures at any stage of gestation. Llamas and alpacas were mated under controlled conditions. Ultrasound exams were conducted to determine pregnancy status 1 month later. Measurements of fetal BPD and TH were conducted from the second month of pregnancy until term. Observation and assessment of fetal TH was difficult during the last 3 months of pregnancy, specially in llamas. Regression curves were calculated from the data as a function of GA, with the best fit represented by the following equations: llama GA=(BPD-0.002399)43.02293,r=0.98,P<0.001; llama GA=(TH-0.07137)46.94485, r=0.95,P<0.001; alpaca GA=(BPD-0.11376)47.23287, r=0.98,P<0.001; alpaca GA=(TH-0.36436)52.87663, r=0.96,P<0.001, where GA was measured in days and BPD and TH in centimeters. Results indicate that ultrasonic measurement of these fetal biometric variables constitute a valuable tool to estimate GA at any stage of pregnancy in these domestic South American camelids.
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Affiliation(s)
- F J Gazitúa
- Facultad de Ciencias Veterinarias y Pecuarias, Universidad de Chile, Casilla 2, Correo 15, La Granja, Santiago, Chile
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Giussani DA, Riquelme RA, Sanhueza EM, Hanson MA, Blanco CE, Llanos AJ. Adrenergic and vasopressinergic contributions to the cardiovascular response to acute hypoxaemia in the llama fetus. J Physiol 1999; 515 ( Pt 1):233-41. [PMID: 9925892 PMCID: PMC2269144 DOI: 10.1111/j.1469-7793.1999.233ad.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/1998] [Accepted: 11/10/1998] [Indexed: 11/28/2022] Open
Abstract
1. The effects of fetal intravenous treatment with phentolamine or a vasopressinergic V1-receptor antagonist on the fetal cardiovascular responses to acute hypoxaemia in the llama were investigated. 2. Six llama fetuses were surgically prepared between 60 and 70 % of gestation under general halothane anaesthesia with vascular catheters and transit-time ultrasonic flow probes around a carotid artery and a femoral artery. At least 4 days after surgery all fetuses were subjected to a 3 h experiment: 1 h of normoxia, 1 h of hypoxaemia and 1 h of recovery while on slow i.v. infusion with saline. On separate days this experiment was repeated with fetal i.v. treatment with either phentolamine or a V1-receptor antagonist dissolved in saline. 3. During saline infusion all llama fetuses responded to acute hypoxaemia with intense femoral vasoconstriction. Phentolamine during normoxia produced hypotension, tachycardia and vasodilatation in both the carotid and the femoral circulations. During hypoxaemia, fetuses treated with phentolamine did not elicit the pronounced femoral vasoconstriction and all died within 20 min of the onset of hypoxaemia. A V1-receptor antagonist produced a femoral vasodilatation during normoxia but did not affect the fetal cardiovascular responses to acute hypoxaemia. 4. In conclusion, alpha-adrenergic and V1-vasopressinergic mechanisms contribute to a basal vasoconstrictor tone in the femoral circulation in the llama fetus. The enhanced femoral vasoconstriction during acute hypoxaemia in the llama fetus is not mediated by stimulation of V1-vasopressin receptors, but is dependent on alpha-adrenergic receptor stimulation. Such alpha-adrenergic efferent mechanisms are indispensable to fetal survival during hypoxaemia in the llama since their abolition leads to cardiovascular collapse and death.
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Affiliation(s)
- D A Giussani
- The Physiological Laboratory, University of Cambridge, Downing Street, Cambridge CB2 3EG, UK
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27
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Abstract
1. This study was designed to investigate the O2 dependence of K+ influx in sheep red cells. Influx was determined using 86Rb+ as a tracer for K+; glass tonometers coupled to a gas mixing pump were used to equilibrate cell samples to the requisite oxygen tension (PO2). 2. Both volume- and H(+)-stimulated K+ influxes in low potassium-containing (LK) sheep red cells were approximately doubled on equilibration with O2 relative to influxes measured in N2.O2-dependent influxes were abolished when Cl- was replaced with NO3-, consistent with mediation by the KCl cotransporter. At pH 7, PO2 required for half-maximal stimulation was 56 +/- 1 mmHg (mean +/- S.E.M., 3 sheep) for the O2-dependent component of K+ influx: thus PO2 values over the physiological range affected K+ influx. 3. K+ influx in fully deoxygenated sheep red cells showed substantial volume and H+ sensitivity. These residual components in N2 were also Cl- dependent, indicating that the KCl cotransporter of LK sheep red cells was active in the absence of O2. 4. Volume-sensitive K+ influxes in high potassium-containing (HK) sheep red cells responded in a similar way to those in cells from LK sheep, although much smaller in magnitude, showing that intracellular [K+] had no significant effect on the O2 dependence of the cotransporter. 5. Intracellular [Mg2+] ([Mg2+]i) was altered by incubating sheep red cells with A23187 (20 microM) and different values of extracellular [Mg2+] ([Mg2+]o). Total [Mg2+]i was determined by atomic absorption spectroscopy and free [Mg2+]i from [Mg2+]o and the Donnan ratio. Total [Mg2+]i was 1.29 +/- 0.08 mM (mean +/- S.E.M., n = 5), similar to that reported in the literature. Estimates of free [Mg2+]i showed an increase from 0.39 +/- 0.05 in oxygenated cells to 0.52 +/- 0.04 mM (mean +/- S.E.M., n = 5; P < 0.05) in deoxygenated ones. 6. Finally, although K+ influxes were altered by pharmacological loading or depletion of cells with Mg2+, the free [Mg2+]i required to affect influxes significantly was outside the physiological range. Results are difficult to reconcile with PO2 modulating KCl cotransport activity directly via changes in free [Mg2+]i or [Mg(2+)-ATP]i.
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Affiliation(s)
- E H Campbell
- Department of Veterinary Preclinical Sciences, University of Liverpool, UK
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Blanco CE, Giussani DA, Riquelme RA, Hanson MA, Llanos AJ. Carotid blood flow changes with behavioral states in the late gestation llama fetus in utero. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 1997; 104:137-41. [PMID: 9466716 DOI: 10.1016/s0165-3806(97)00174-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
This study tested the hypothesis that in the llama fetus changes in cerebral blood flow are closely associated with changes in cerebral oxidative metabolism such as occur during transitions between electrocortical states. For the first time reported in any species, instantaneous changes in common carotid blood flow, employed as a continuous index of cerebrovascular perfusion, were related to instantaneous changes in electrocortical activity. Three late gestation fetal llamas were surgically prepared under general anesthesia with vascular catheters, a tracheal and amniotic catheter, and with electrodes implanted to monitor the fetal electrocorticogram (ECoG). In addition, Transonic flow probes were placed around a common carotid artery and a femoral artery. At least 4 days after surgery fetal arterial blood, amniotic and tracheal pressures, carotid and femoral blood flows and the fetal ECoG were recorded continuously. Our results suggest a close association between increases in common carotid blood flow and low voltage ECoG in the llama fetus. Close coupling between instantaneous changes in carotid blood flow and electrocortical states together with the lack of an increase in brain blood flow without increased cerebral oxygen extraction during hypoxemia in the llama fetus supports a fall in cerebral oxidative metabolism in this species during hypoxemic episodes.
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Affiliation(s)
- C E Blanco
- Department of Pediatrics, University of Maastricht, The Netherlands.
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