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Reid C, Romero M, Chang SB, Osman N, Puglisi JL, Wilson CG, Blood AB, Zhang L, Wilson SM. Long-Term Hypoxia Negatively Influences Ca2+ Signaling in Basilar Arterial Myocytes of Fetal and Adult Sheep. Front Physiol 2022; 12:760176. [PMID: 35115953 PMCID: PMC8804533 DOI: 10.3389/fphys.2021.760176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Accepted: 10/25/2021] [Indexed: 11/21/2022] Open
Abstract
Cerebral arterial vasoreactivity is vital to the regulation of cerebral blood flow. Depolarization of arterial myocytes elicits whole-cell Ca2+ oscillations as well as subcellular Ca2+ sparks due to activation of ryanodine receptors on the sarcoplasmic reticulum. Previous evidence illustrates that contraction of cerebral arteries from sheep and underlying Ca2+ signaling pathways are modified by age and that long-term hypoxia (LTH) causes aberrations in Ca2+ signaling pathways and downstream effectors impacting vasoregulation. We hypothesize that age and LTH affect the influence of membrane depolarization on whole-cell intracellular Ca2+ oscillations and sub-cellular Ca2+ spark activity in cerebral arteries. To test this hypothesis, we examined Ca2+ oscillatory and spark activities using confocal fluorescence imaging techniques of Fluo-4 loaded basilar arterial myocytes of low- and high-altitude term fetal (∼145 days of gestation) and adult sheep, where high-altitude pregnant and non-pregnant sheep were placed at 3,801 m for >100 days. Ca2+ oscillations and sparks were recorded using an in situ preparation evaluated in the absence or presence of 30 mM K+ (30K) to depolarize myocytes. Myocytes from adult animals tended to have a lower basal rate of whole-cell Ca2+ oscillatory activity and 30K increased the activity within cells. LTH decreased the ability of myocytes to respond to depolarization independent of age. These observations illustrate that both altitude and age play a role in affecting whole-cell and localized Ca2+ signaling, which are important to arterial vasoreactivity and cerebral blood flow.
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Affiliation(s)
- Casey Reid
- Lawrence D. Longo, MD Center for Perinatal Biology, Loma Linda University School of Medicine, Loma Linda, CA, United States
| | - Monica Romero
- Advanced Imaging and Microscopy Core, Loma Linda University School of Medicine, Loma Linda, CA, United States
| | - Stephanie B. Chang
- Lawrence D. Longo, MD Center for Perinatal Biology, Loma Linda University School of Medicine, Loma Linda, CA, United States
| | - Noah Osman
- Lawrence D. Longo, MD Center for Perinatal Biology, Loma Linda University School of Medicine, Loma Linda, CA, United States
| | - Jose L. Puglisi
- Department of Biostatistics, School of Medicine, California Northstate University, Elk Grove, CA, United States
| | - Christopher G. Wilson
- Lawrence D. Longo, MD Center for Perinatal Biology, Loma Linda University School of Medicine, Loma Linda, CA, United States
| | - Arlin B. Blood
- Lawrence D. Longo, MD Center for Perinatal Biology, Loma Linda University School of Medicine, Loma Linda, CA, United States
| | - Lubo Zhang
- Lawrence D. Longo, MD Center for Perinatal Biology, Loma Linda University School of Medicine, Loma Linda, CA, United States
| | - Sean M. Wilson
- Lawrence D. Longo, MD Center for Perinatal Biology, Loma Linda University School of Medicine, Loma Linda, CA, United States
- Advanced Imaging and Microscopy Core, Loma Linda University School of Medicine, Loma Linda, CA, United States
- *Correspondence: Sean M. Wilson,
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2
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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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3
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Moretta D, Papamatheakis DG, Morris DP, Giri PC, Blood Q, Murray S, Ramzy M, Romero M, Vemulakonda S, Lauw S, Longo LD, Zhang L, Wilson SM. Long-Term High-Altitude Hypoxia and Alpha Adrenoceptor-Dependent Pulmonary Arterial Contractions in Fetal and Adult Sheep. Front Physiol 2019; 10:1032. [PMID: 31555139 PMCID: PMC6723549 DOI: 10.3389/fphys.2019.01032] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Accepted: 07/26/2019] [Indexed: 01/01/2023] Open
Abstract
Autonomic innervation of the pulmonary vasculature triggers vasomotor contractility predominately through activation of alpha-adrenergic receptors (α-ARs) in the fetal circulation. Long-term hypoxia (LTH) modulates pulmonary vasoconstriction potentially through upregulation of α1-AR in the vasculature. Our study aimed to elucidate the role of α-AR in phenylephrine (PE)-induced pulmonary vascular contractility, comparing the effects of LTH in the fetal and adult periods on α-AR subtypes and PE-mediated Ca2+ responses and contractions. To address this, we performed wire myography, Ca2+ imaging, and mRNA analysis of pulmonary arteries from ewes and fetuses exposed to LTH or normoxia. Postnatal maturation depressed PE-mediated contractile responses. α2-AR activation contracted fetal vessels; however, this was suppressed by LTH. α1A- and α1B-AR subtypes contributed to arterial contractions in all groups. The α1D-AR was also important to contractility in fetal normoxic vessels and LTH mitigated its function. Postnatal maturity increased the number of myocytes with PE-triggered Ca2+ responses while LTH decreased the percentage of fetal myocytes reacting to PE. The difference between myocyte Ca2+ responsiveness and vessel contractility suggests that fetal arteries are sensitized to changes in Ca2+. The results illustrate that α-adrenergic signaling and vascular function change during development and that LTH modifies adrenergic signaling. These changes may represent components in the etiology of pulmonary vascular disease and foretell the therapeutic potential of adrenergic receptor antagonists in the treatment of pulmonary hypertension.
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Affiliation(s)
- Dafne Moretta
- Pulmonary and Critical Care, School of Medicine, Loma Linda University, Loma Linda, CA, United States
| | | | - Daniel P Morris
- Lawrence D. Longo MD Center for Perinatal Biology, School of Medicine, Loma Linda University, Loma Linda, CA, United States
| | - Paresh C Giri
- Pulmonary and Critical Care, School of Medicine, Loma Linda University, Loma Linda, CA, United States
| | - Quintin Blood
- Lawrence D. Longo MD Center for Perinatal Biology, School of Medicine, Loma Linda University, Loma Linda, CA, United States
| | - Samuel Murray
- Lawrence D. Longo MD Center for Perinatal Biology, School of Medicine, Loma Linda University, Loma Linda, CA, United States
| | - Marian Ramzy
- Lawrence D. Longo MD Center for Perinatal Biology, School of Medicine, Loma Linda University, Loma Linda, CA, United States
| | - Monica Romero
- Advanced Imaging and Microscopy Core, School of Medicine, Loma Linda University, Loma Linda, CA, United States
| | - Srilakshmi Vemulakonda
- Pulmonary and Critical Care, School of Medicine, Loma Linda University, Loma Linda, CA, United States
| | - Sidney Lauw
- Lawrence D. Longo MD Center for Perinatal Biology, School of Medicine, Loma Linda University, Loma Linda, CA, United States
| | - Lawrence D Longo
- Lawrence D. Longo MD Center for Perinatal Biology, School of Medicine, Loma Linda University, Loma Linda, CA, United States
| | - Lubo Zhang
- Lawrence D. Longo MD Center for Perinatal Biology, School of Medicine, Loma Linda University, Loma Linda, CA, United States
| | - Sean M Wilson
- Lawrence D. Longo MD Center for Perinatal Biology, School of Medicine, Loma Linda University, Loma Linda, CA, United States.,Advanced Imaging and Microscopy Core, School of Medicine, Loma Linda University, Loma Linda, CA, United States
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Ducsay CA, Goyal R, Pearce WJ, Wilson S, Hu XQ, Zhang L. Gestational Hypoxia and Developmental Plasticity. Physiol Rev 2018; 98:1241-1334. [PMID: 29717932 PMCID: PMC6088145 DOI: 10.1152/physrev.00043.2017] [Citation(s) in RCA: 105] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Hypoxia is one of the most common and severe challenges to the maintenance of homeostasis. Oxygen sensing is a property of all tissues, and the response to hypoxia is multidimensional involving complicated intracellular networks concerned with the transduction of hypoxia-induced responses. Of all the stresses to which the fetus and newborn infant are subjected, perhaps the most important and clinically relevant is that of hypoxia. Hypoxia during gestation impacts both the mother and fetal development through interactions with an individual's genetic traits acquired over multiple generations by natural selection and changes in gene expression patterns by altering the epigenetic code. Changes in the epigenome determine "genomic plasticity," i.e., the ability of genes to be differentially expressed according to environmental cues. The genomic plasticity defined by epigenomic mechanisms including DNA methylation, histone modifications, and noncoding RNAs during development is the mechanistic substrate for phenotypic programming that determines physiological response and risk for healthy or deleterious outcomes. This review explores the impact of gestational hypoxia on maternal health and fetal development, and epigenetic mechanisms of developmental plasticity with emphasis on the uteroplacental circulation, heart development, cerebral circulation, pulmonary development, and the hypothalamic-pituitary-adrenal axis and adipose tissue. The complex molecular and epigenetic interactions that may impact an individual's physiology and developmental programming of health and disease later in life are discussed.
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Affiliation(s)
- Charles A. Ducsay
- The Lawrence D. Longo, MD Center for Perinatal Biology, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, California
| | - Ravi Goyal
- The Lawrence D. Longo, MD Center for Perinatal Biology, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, California
| | - William J. Pearce
- The Lawrence D. Longo, MD Center for Perinatal Biology, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, California
| | - Sean Wilson
- The Lawrence D. Longo, MD Center for Perinatal Biology, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, California
| | - Xiang-Qun Hu
- The Lawrence D. Longo, MD Center for Perinatal Biology, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, California
| | - Lubo Zhang
- The Lawrence D. Longo, MD Center for Perinatal Biology, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, California
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5
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Moraga FA, Miranda G, López V, Vallejos C, Silva D. Chronic Intermittent Hypobaric Hypoxia (4600 M) Attenuates Pulmonary Vasodilation Induced by Acetylcholine or Sodium Nitroprusside. High Alt Med Biol 2018; 19:149-155. [PMID: 29565678 DOI: 10.1089/ham.2017.0012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Moraga, Fernando A., Giselle Miranda, Vasthi López, Carmen Vallejos, and Daniel Silva. Chronic intermittent hypobaric hypoxia (4600 M) attenuates pulmonary vasodilation induced by acetylcholine or sodium nitroprusside. High Alt Med Biol. 19:149-155, 2018. BACKGROUND Previous studies performed in rats exposed to chronic intermittent hypobaric hypoxia (CIHH), at a simulated altitude of 4600 m, showed reduced nitric oxide (NO) production, increased arginase activity, and increased oxidative stress. However, studies on vascular function are scarce. Our aim was to measure plasma nitrate and nitrite (NOx) concentration and study pulmonary vascular function in rats exposed to CIHH in the presence of potassium chloride (KCl), acetylcholine (Ach), and sodium nitroprusside (SNP). METHODS Thirty male Wistar rats were divided into two groups: A control group (normoxia (N), n = 10) and a CIHH group (2N × 2H × 30 days, n = 20). CIHH exposure was performed in a hypobaric chamber at 428 Torr (4600 m). Noninvasive systolic blood pressure (SBP), heart rate, and body weight (BW) were measured. Blood samples were obtained to measure NOx levels and hematocrit (Hct). CIHH animals that gained BW and presented a Hct <20% and maintained SBP were classified as tolerant, and animals that lost >30% of their BW, increased Hct and SBP >20% were classified as intolerant. Animals were sacrificed and small pulmonary arteries (SPA) were obtained to perform concentration-response curves to KCl, Ach, and SNP. RESULTS AND CONCLUSIONS Intolerant rats (30%) had decreased NOx levels. SPA had a larger vasocontraction response to KCl and a lower dilation response to SNP in the SPA compared to tolerant and control animals. In addition, SPA had a lower dilatation response to Ach compared with the control. Together, these results show that CIHH alters endothelium-dependent vasodilation.
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Affiliation(s)
- Fernando A Moraga
- Laboratory of Physiology, Hypoxia and Vascular Function, Department of Biomedical Science, Faculty of Medicine, Universidad Católica del Norte, Coquimbo, Chile
| | - Giselle Miranda
- Laboratory of Physiology, Hypoxia and Vascular Function, Department of Biomedical Science, Faculty of Medicine, Universidad Católica del Norte, Coquimbo, Chile
| | - Vasthi López
- Laboratory of Physiology, Hypoxia and Vascular Function, Department of Biomedical Science, Faculty of Medicine, Universidad Católica del Norte, Coquimbo, Chile
| | - Carmen Vallejos
- Laboratory of Physiology, Hypoxia and Vascular Function, Department of Biomedical Science, Faculty of Medicine, Universidad Católica del Norte, Coquimbo, Chile
| | - Daniel Silva
- Laboratory of Physiology, Hypoxia and Vascular Function, Department of Biomedical Science, Faculty of Medicine, Universidad Católica del Norte, Coquimbo, Chile
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6
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Blum-Johnston C, Thorpe RB, Wee C, Opsahl R, Romero M, Murray S, Brunelle A, Blood Q, Wilson R, Blood AB, Zhang L, Longo LD, Pearce WJ, Wilson SM. Long-term hypoxia uncouples Ca 2+ and eNOS in bradykinin-mediated pulmonary arterial relaxation. Am J Physiol Regul Integr Comp Physiol 2018. [PMID: 29513562 DOI: 10.1152/ajpregu.00311.2017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Bradykinin-induced activation of the pulmonary endothelium triggers a rise in intracellular Ca2+ that activates nitric oxide (NO)-dependent vasorelaxation. Chronic hypoxia is commonly associated with increased pulmonary vascular tone, which can cause pulmonary hypertension in responsive individuals. In the present study, we tested the hypothesis that long-term high-altitude hypoxia (LTH) diminishes bradykinin-induced Ca2+ signals and inhibits endothelial nitric oxide synthase (eNOS), prostacyclin (PGI2), and large-conductance K+ (BKCa) channels in sheep, which are moderately responsive to LTH, resulting in decreased pulmonary arterial vasorelaxation. Pulmonary arteries were isolated from ewes kept near sea level (720 m) or at high altitude (3,801 m) for >100 days. Vessel force was measured with wire myography and endothelial intracellular Ca2+ with confocal microscopy. eNOS was inhibited with 100 μM NG-nitro-l-arginine methyl ester (l-NAME), PGI2 production was inhibited with 10 µM indomethacin that inhibits cyclooxygenase, and BKCa channels were blocked with 1 mM tetraethylammonium. Bradykinin-induced endothelial Ca2+ signals increased following LTH, but bradykinin relaxation decreased. Furthermore, some vessels contracted in response to bradykinin after LTH. l-NAME sensitivity decreased, suggesting that eNOS dysfunction played a role in uncoupling Ca2+ signals and bradykinin relaxation. The Ca2+ ionophore A-23187 (10 µM) elicited an enhanced Ca2+ response following LTH while relaxation was unchanged although l-NAME sensitivity increased. Additionally, BKCa function decreased during bradykinin relaxation following LTH. Western analysis showed that BKCa α-subunit expression was increased by LTH while that for the β1 subunit was unchanged. Overall, these results suggest that those even moderately responsive to LTH can have impaired endothelial function.
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Affiliation(s)
- Carla Blum-Johnston
- Lawrence D. Longo, MD Center for Perinatal Biology, Loma Linda University School of Medicine , Loma Linda, California.,Center for Health Disparities and Molecular Medicine, Loma Linda University School of Medicine , Loma Linda, California
| | - Richard B Thorpe
- Lawrence D. Longo, MD Center for Perinatal Biology, Loma Linda University School of Medicine , Loma Linda, California
| | - Chelsea Wee
- Lawrence D. Longo, MD Center for Perinatal Biology, Loma Linda University School of Medicine , Loma Linda, California
| | - Raechel Opsahl
- Lawrence D. Longo, MD Center for Perinatal Biology, Loma Linda University School of Medicine , Loma Linda, California
| | - Monica Romero
- Advanced Imaging and Microscopy Core, Loma Linda University School of Medicine , Loma Linda, California
| | - Samuel Murray
- Lawrence D. Longo, MD Center for Perinatal Biology, Loma Linda University School of Medicine , Loma Linda, California
| | - Alexander Brunelle
- Lawrence D. Longo, MD Center for Perinatal Biology, Loma Linda University School of Medicine , Loma Linda, California
| | - Quintin Blood
- Lawrence D. Longo, MD Center for Perinatal Biology, Loma Linda University School of Medicine , Loma Linda, California
| | - Rachael Wilson
- Lawrence D. Longo, MD Center for Perinatal Biology, Loma Linda University School of Medicine , Loma Linda, California
| | - Arlin B Blood
- Lawrence D. Longo, MD Center for Perinatal Biology, Loma Linda University School of Medicine , Loma Linda, California
| | - Lubo Zhang
- Lawrence D. Longo, MD Center for Perinatal Biology, Loma Linda University School of Medicine , Loma Linda, California
| | - Lawrence D Longo
- Lawrence D. Longo, MD Center for Perinatal Biology, Loma Linda University School of Medicine , Loma Linda, California
| | - William J Pearce
- Lawrence D. Longo, MD Center for Perinatal Biology, Loma Linda University School of Medicine , Loma Linda, California
| | - Sean M Wilson
- Lawrence D. Longo, MD Center for Perinatal Biology, Loma Linda University School of Medicine , Loma Linda, California.,Advanced Imaging and Microscopy Core, Loma Linda University School of Medicine , Loma Linda, California
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7
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Shen CP, Romero M, Brunelle A, Wolfe C, Dobyns A, Francis M, Taylor MS, Puglisi JL, Longo LD, Zhang L, Wilson CG, Wilson SM. Long-term high-altitude hypoxia influences pulmonary arterial L-type calcium channel-mediated Ca 2+ signals and contraction in fetal and adult sheep. Am J Physiol Regul Integr Comp Physiol 2017; 314:R433-R446. [PMID: 29167165 DOI: 10.1152/ajpregu.00154.2017] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Long-term hypoxia (LTH) has a profound effect on pulmonary arterial vasoconstriction in the fetus and adult. Dysregulation in Ca2+ signaling is important during the development of LTH-induced pulmonary hypertension. In the present study, we tested the hypothesis that L-type Ca2+ channels (CaL), which are voltage dependent and found in smooth, skeletal, and cardiac muscle, are important in the adaptation of pulmonary arterial contractions in postnatal maturation and in response to LTH. Pulmonary arteries were isolated from fetal or adult sheep maintained at low or high altitude (3,801 m) for >100 days. The effects were measured using an L-type Ca2+ channel opener FPL 64176 (FPL) in the presence or absence of an inhibitor, Nifedipine (NIF) on arterial contractions, intracellular Ca2+ oscillations, and ryanodine receptor-driven Ca2+ sparks. FPL induced pulmonary arterial contractions in all groups were sensitive to NIF. However, when compared with 125 mM K+, FPL contractions were greater in fetuses than in adults. FPL reduced Ca2+ oscillations in myocytes of adult but not fetal arteries, independently of altitude. The FPL effects on Ca2+ oscillations were reversed by NIF in myocytes of hypoxic but not normoxic adults. FPL failed to enhance Ca2+ spark frequency and had little impact on spatiotemporal firing characteristics. These data suggest that CaL-dependent contractions are largely uncoupled from intracellular Ca2+ oscillations and the development of Ca2+ sparks. This raises questions regarding the coupling of pulmonary arterial contractility to membrane depolarization, attendant CaL facilitation, and the related associations with the activation of Ca2+ oscillations and Ca2+ sparks.
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Affiliation(s)
- Christine P Shen
- Lawrence D. Longo, MD Center for Perinatal Biology, Loma Linda University School of Medicine , Loma Linda, California
| | - Monica Romero
- Advanced Imaging and Microscopy Core, Loma Linda University School of Medicine , Loma Linda, California
| | - Alexander Brunelle
- Lawrence D. Longo, MD Center for Perinatal Biology, Loma Linda University School of Medicine , Loma Linda, California
| | - Craig Wolfe
- Lawrence D. Longo, MD Center for Perinatal Biology, Loma Linda University School of Medicine , Loma Linda, California
| | - Abigail Dobyns
- Lawrence D. Longo, MD Center for Perinatal Biology, Loma Linda University School of Medicine , Loma Linda, California
| | - Michael Francis
- Department of Physiology, University of South Alabama College of Medicine , Mobile, Alabama
| | - Mark S Taylor
- Department of Physiology, University of South Alabama College of Medicine , Mobile, Alabama
| | - Jose L Puglisi
- Department of Biostatistics, California Northstate University School of Medicine , Elk Grove, California
| | - Lawrence D Longo
- Lawrence D. Longo, MD Center for Perinatal Biology, Loma Linda University School of Medicine , Loma Linda, California
| | - Lubo Zhang
- Lawrence D. Longo, MD Center for Perinatal Biology, Loma Linda University School of Medicine , Loma Linda, California
| | - Christopher G Wilson
- Lawrence D. Longo, MD Center for Perinatal Biology, Loma Linda University School of Medicine , Loma Linda, California
| | - Sean M Wilson
- Lawrence D. Longo, MD Center for Perinatal Biology, Loma Linda University School of Medicine , Loma Linda, California
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8
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Giang M, Papamatheakis DG, Nguyen D, Paez R, Blum Johnston C, Kim J, Brunnell A, Blood Q, Goyal R, Longo LD, Wilson SM. Muscarinic Receptor Activation Affects Pulmonary Artery Contractility in Sheep: The Impact of Maturation and Chronic Hypoxia on Endothelium-Dependent and Endothelium-Independent Function. High Alt Med Biol 2017; 17:122-32. [PMID: 27281473 DOI: 10.1089/ham.2015.0116] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Giang, Michael, Demosthenes G. Papamatheakis, Dan Nguyen, Ricardo Paez, Carla Blum Johnston, Joon Kim, Alexander Brunnell, Quintin Blood, Ravi Goyal, Lawrence D. Longo, and Sean M. Wilson. Muscarinic receptor activation affects pulmonary artery contractility in sheep: the impact of maturation and chronic hypoxia on endothelium-dependent and endothelium-independent function. High Alt Med Biol. 17:122-132, 2015.-Muscarinic receptor activation in the pulmonary vasculature can cause endothelium-dependent vasodilation and smooth muscle-dependent vasoconstriction. Chronic hypoxia (CH) can modify both of these responses. This study aimed to assess the combined influence of CH and maturation on endothelium-dependent and endothelium-independent muscarinic-induced vasoreactivity. This was accomplished by performing wire myography on endothelium-intact or endothelium-disrupted pulmonary arterial rings isolated from normoxic or CH fetal and adult sheep. In endothelium-intact arteries, vasodilation was evaluated using cumulative bradykinin doses in phenylephrine and carbachol precontracted pulmonary arterial segments; and vasoconstriction was examined using cumulative doses of carbachol following bradykinin predilation. Effects of nonselective (atropine) and selective M1 (pirenzepine), M2 (AFDX116), and M3 (4-DAMP and Dau5884) muscarinic receptor antagonists were assessed in disrupted arteries. In normoxic arteries, bradykinin relaxation was twofold greater in the adult compared to fetus, while carbachol contraction was fourfold greater. In adult arteries, CH increased bradykinin relaxation and carbachol contraction. In vessels with intact endothelium, maturation and CH augmented maximal response and efficacy for carbachol constriction and bradykinin relaxation. Approximately 50%-80% of adult normoxic and CH endothelium-disrupted arteries contracted to acetylcholine, while ∼50% of fetal normoxic and ∼10% of CH arteries responded. Atropine reduced carbachol-induced contraction in all vessels. Adult normoxic vessels were most responsive to M3 antagonism, fetal to M2 antagonism, while M1 inhibition had no effect. Overall, muscarinic-induced pulmonary arterial contraction is partially endothelium dependent and appears to develop after birth. Fetuses are more reliant on M3 receptors while M2 receptors predominate in adults, whereas CH augments muscarinic-dependent pulmonary vasoconstriction in both.
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Affiliation(s)
- Michael Giang
- 1 Center for Perinatal Biology, Loma Linda University School of Medicine , Loma Linda, California
| | | | - Dan Nguyen
- 3 Department of Pharmacology, University of Mississippi School of Pharmacy , University, Mississippi
| | - Ricardo Paez
- 1 Center for Perinatal Biology, Loma Linda University School of Medicine , Loma Linda, California.,4 Center for Health Disparities and Molecular Medicine, School of Medicine, Loma Linda University , Loma Linda, California
| | - Carla Blum Johnston
- 1 Center for Perinatal Biology, Loma Linda University School of Medicine , Loma Linda, California.,4 Center for Health Disparities and Molecular Medicine, School of Medicine, Loma Linda University , Loma Linda, California
| | - Joon Kim
- 1 Center for Perinatal Biology, Loma Linda University School of Medicine , Loma Linda, California.,5 Division of Pulmonary and Critical Care, Loma Linda University School of Medicine , Loma Linda, California
| | - Alexander Brunnell
- 1 Center for Perinatal Biology, Loma Linda University School of Medicine , Loma Linda, California
| | - Quintin Blood
- 1 Center for Perinatal Biology, Loma Linda University School of Medicine , Loma Linda, California
| | - Ravi Goyal
- 1 Center for Perinatal Biology, Loma Linda University School of Medicine , Loma Linda, California
| | - Lawrence D Longo
- 1 Center for Perinatal Biology, Loma Linda University School of Medicine , Loma Linda, California
| | - Sean M Wilson
- 1 Center for Perinatal Biology, Loma Linda University School of Medicine , Loma Linda, California
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Castillo-Galán S, Quezada S, Moraga FA, Ebensperger G, Herrera EA, Beñaldo F, Hernandez I, Ebensperger R, Ramirez S, Llanos AJ, Reyes RV. 2-AMINOETHYLDIPHENYLBORINATE MODIFIES THE PULMONARY CIRCULATION IN PULMONARY HYPERTENSIVE NEWBORN LAMBS WITH PARTIAL GESTATION AT HIGH ALTITUDE. Am J Physiol Lung Cell Mol Physiol 2016; 311:L788-L799. [PMID: 27542806 DOI: 10.1152/ajplung.00230.2016] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 08/14/2016] [Indexed: 12/22/2022] Open
Abstract
Calcium signaling through store operated channels (SOC) is involved in hypoxic pulmonary hypertension. We determined whether a treatment with 2-aminoethyldiphenylborinate (2-APB), a compound with SOC blocker activity, reduces pulmonary hypertension and vascular remodeling. Twelve newborn lambs exposed to perinatal chronic hypoxia were studied, 6 of them received a 2-APB treatment and the other 6 received vehicle treatment, for 10 days in both cases. Throughout this period, we recorded cardiopulmonary variables and on day 11 we evaluated the response to an acute hypoxic challenge. Additionally, we assessed the vasoconstrictor and vasodilator function in isolated pulmonary arteries as well as their remodeling in lung slices. 2-APB reduced pulmonary arterial pressure at the third and tenth days, cardiac output between the fourth and eighth days, and pulmonary vascular resistance at the tenth day of treatment. The pulmonary vasoconstrictor response to acute hypoxia was reduced by the end of treatment. 2-APB also decreased maximal vasoconstrictor response to the thromboxane mimetic U46619 and endothelin-1 and increased maximal relaxation to 8-Br-cGMP. The maximal relaxation and potency to phosphodiesterase-5 and Rho-kinase inhibition with sildenafil and fasudil respectively, were also increased. Finally, 2-APB reduced the medial and adventitial layers' thickness, the expression of α-actin and the percentage of Ki67+ nuclei of small pulmonary arteries. Taken together, our results indicate that 2-APB reduces pulmonary hypertension, vasoconstrictor responses and pathological remodeling in pulmonary hypertensive lambs. We conclude that SOC targeting may be a useful strategy for the treatment of neonatal pulmonary hypertension, however, further testing of specific blockers is needed.
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Affiliation(s)
| | - Sebastián Quezada
- Universidad de Chile, Facultad de Medicina, Instituto de Ciencias Biomédicas (ICBM)
| | | | - Germán Ebensperger
- Facultad de Medicina, Universidad de Chile, Instituto de Ciencias Biomédicas (ICBM), Santiago, Chile
| | | | | | - Ismael Hernandez
- Facultad de Medicina, Universidad de Chile, Instituto de Ciencias Biomédicas (ICBM), Santiago, Chile
| | - Renato Ebensperger
- Facultad de Medicina, Universidad de Chile, Instituto de Ciencias Biomédicas (ICBM), Santiago, Chile
| | - Santiago Ramirez
- Facultad de Medicina, Universidad de Chile, Instituto de Ciencias Biomédicas (ICBM), Santiago, Chile
| | | | - Roberto V Reyes
- Universidad de Chile, Facultad de Medicina, Instituto de Ciencias Biomédicas (ICBM)
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10
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Blum-Johnston C, Thorpe RB, Wee C, Romero M, Brunelle A, Blood Q, Wilson R, Blood AB, Francis M, Taylor MS, Longo LD, Pearce WJ, Wilson SM. Developmental acceleration of bradykinin-dependent relaxation by prenatal chronic hypoxia impedes normal development after birth. Am J Physiol Lung Cell Mol Physiol 2015; 310:L271-86. [PMID: 26637638 DOI: 10.1152/ajplung.00340.2015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Accepted: 12/02/2015] [Indexed: 11/22/2022] Open
Abstract
Bradykinin-induced activation of the pulmonary endothelium triggers nitric oxide production and other signals that cause vasorelaxation, including stimulation of large-conductance Ca(2+)-activated K(+) (BKCa) channels in myocytes that hyperpolarize the plasma membrane and decrease intracellular Ca(2+). Intrauterine chronic hypoxia (CH) may reduce vasorelaxation in the fetal-to-newborn transition and contribute to pulmonary hypertension of the newborn. Thus we examined the effects of maturation and CH on the role of BKCa channels during bradykinin-induced vasorelaxation by examining endothelial Ca(2+) signals, wire myography, and Western immunoblots on pulmonary arteries isolated from near-term fetal (∼ 140 days gestation) and newborn, 10- to 20-day-old, sheep that lived in normoxia at 700 m or in CH at high altitude (3,801 m) for >100 days. CH enhanced bradykinin-induced relaxation of fetal vessels but decreased relaxation in newborns. Endothelial Ca(2+) responses decreased with maturation but increased with CH. Bradykinin-dependent relaxation was sensitive to 100 μM nitro-L-arginine methyl ester or 10 μM 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, supporting roles for endothelial nitric oxide synthase and soluble guanylate cyclase activation. Indomethacin blocked relaxation in CH vessels, suggesting upregulation of PLA2 pathways. BKCa channel inhibition with 1 mM tetraethylammonium reduced bradykinin-induced vasorelaxation in the normoxic newborn and fetal CH vessels. Maturation reduced whole cell BKCa channel α1-subunit expression but increased β1-subunit expression. These results suggest that CH amplifies the contribution of BKCa channels to bradykinin-induced vasorelaxation in fetal sheep but stunts further development of this vasodilatory pathway in newborns. This involves complex changes in multiple components of the bradykinin-signaling axes.
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Affiliation(s)
- Carla Blum-Johnston
- Center for Perinatal Biology, Loma Linda University School of Medicine, Loma Linda, California; Center for Health Disparities and Molecular Medicine, Loma Linda University School of Medicine, Loma Linda, California
| | - Richard B Thorpe
- Center for Perinatal Biology, Loma Linda University School of Medicine, Loma Linda, California
| | - Chelsea Wee
- Center for Perinatal Biology, Loma Linda University School of Medicine, Loma Linda, California
| | - Monica Romero
- Center for Perinatal Biology, Loma Linda University School of Medicine, Loma Linda, California; Advanced Imaging and Microscopy Core, Loma Linda University School of Medicine, Loma Linda, California
| | - Alexander Brunelle
- Center for Perinatal Biology, Loma Linda University School of Medicine, Loma Linda, California
| | - Quintin Blood
- Center for Perinatal Biology, Loma Linda University School of Medicine, Loma Linda, California
| | - Rachael Wilson
- Center for Perinatal Biology, Loma Linda University School of Medicine, Loma Linda, California;
| | - Arlin B Blood
- Center for Perinatal Biology, Loma Linda University School of Medicine, Loma Linda, California; Division of Neonatology, Department of Pediatrics, Loma Linda University School of Medicine, Loma Linda, California; and
| | - Michael Francis
- Department of Physiology and Cell Biology, University of South Alabama College of Medicine, Birmingham, Alabama
| | - Mark S Taylor
- Department of Physiology and Cell Biology, University of South Alabama College of Medicine, Birmingham, Alabama
| | - Lawrence D Longo
- Center for Perinatal Biology, Loma Linda University School of Medicine, Loma Linda, California
| | - William J Pearce
- Center for Perinatal Biology, Loma Linda University School of Medicine, Loma Linda, California
| | - Sean M Wilson
- Center for Perinatal Biology, Loma Linda University School of Medicine, Loma Linda, California; Advanced Imaging and Microscopy Core, Loma Linda University School of Medicine, Loma Linda, California
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11
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Papamatheakis DG, Chundu M, Blood AB, Wilson SM. Prenatal programming of pulmonary hypertension induced by chronic hypoxia or ductal ligation in sheep. Pulm Circ 2014; 3:757-80. [PMID: 25006393 DOI: 10.1086/674767] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Accepted: 07/28/2013] [Indexed: 11/03/2022] Open
Abstract
Pulmonary hypertension of the newborn is caused by a spectrum of functional and structural abnormalities of the cardiopulmonary circuit. The existence of multiple etiologies and an incomplete understanding of the mechanisms of disease progression have hindered the development of effective therapies. Animal models offer a means of gaining a better understanding of the fundamental basis of the disease. To that effect, a number of experimental animal models are being used to generate pulmonary hypertension in the fetus and newborn. In this review, we compare the mechanisms associated with pulmonary hypertension caused by two such models: in utero ligation of the ductus arteriosus and chronic perinatal hypoxia in sheep fetuses and newborns. In this manner, we make direct comparisons between ductal ligation and chronic hypoxia with respect to the associated mechanisms of disease, since multiple studies have been performed with both models in a single species. We present evidence that the mechanisms associated with pulmonary hypertension are dependent on the type of stress to which the fetus is subjected. Such an analysis allows for a more thorough evaluation of the disease etiology, which can help focus clinical treatments. The final part of the review provides a clinical appraisal of current treatment strategies and lays the foundation for developing individualized therapies that depend on the causative factors.
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Affiliation(s)
- Demosthenes G Papamatheakis
- Division of Pulmonary and Critical Care, University of California San Diego Health System, San Diego, California, USA
| | - Madalitso Chundu
- Center for Perinatal Biology, Loma Linda University School of Medicine, Loma Linda, California, USA
| | - Arlin B Blood
- Department of Pediatrics Division of Neonatology, and Center for Perinatal Biology, Loma Linda University School of Medicine, Loma Linda, California, USA
| | - Sean M Wilson
- Center for Perinatal Biology, Loma Linda University School of Medicine, Loma Linda, California, USA
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12
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Papamatheakis DG, Blood AB, Kim JH, Wilson SM. Antenatal hypoxia and pulmonary vascular function and remodeling. Curr Vasc Pharmacol 2014; 11:616-40. [PMID: 24063380 DOI: 10.2174/1570161111311050006] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Revised: 06/25/2012] [Accepted: 07/12/2012] [Indexed: 01/02/2023]
Abstract
This review provides evidence that antenatal hypoxia, which represents a significant and worldwide problem, causes prenatal programming of the lung. A general overview of lung development is provided along with some background regarding transcriptional and signaling systems of the lung. The review illustrates that antenatal hypoxic stress can induce a continuum of responses depending on the species examined. Fetuses and newborns of certain species and specific human populations are well acclimated to antenatal hypoxia. However, antenatal hypoxia causes pulmonary vascular disease in fetuses and newborns of most mammalian species and humans. Disease can range from mild pulmonary hypertension, to severe vascular remodeling and dangerous elevations in pressure. The timing, length, and magnitude of the intrauterine hypoxic stress are important to disease development, however there is also a genetic-environmental relationship that is not yet completely understood. Determining the origins of pulmonary vascular remodeling and pulmonary hypertension and their associated effects is a challenging task, but is necessary in order to develop targeted therapies for pulmonary hypertension in the newborn due to antenatal hypoxia that can both treat the symptoms and curtail or reverse disease progression.
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Affiliation(s)
- Demosthenes G Papamatheakis
- Center for Perinatal Biology, Loma Linda University School of Medicine, 11234 Anderson Street, Loma Linda, 92350 CA, USA.
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13
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Yoo HY, Zeifman A, Ko EA, Smith KA, Chen J, Machado RF, Zhao YY, Minshall RD, Yuan JXJ. Optimization of isolated perfused/ventilated mouse lung to study hypoxic pulmonary vasoconstriction. Pulm Circ 2013; 3:396-405. [PMID: 24015341 PMCID: PMC3757835 DOI: 10.4103/2045-8932.114776] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Hypoxic pulmonary vasoconstriction (HPV) is a compensatory physiological mechanism in the lung that optimizes the matching of ventilation to perfusion and thereby maximizes gas exchange. Historically, HPV has been primarily studied in isolated perfused/ventilated lungs; however, the results of these studies have varied greatly due to different experimental conditions and species. Therefore, in the present study, we utilized the mouse isolated perfused/ventilated lung model for investigation of the role of extracellular Ca2+ and caveolin-1 and endothelial nitric oxide synthase expression on HPV. We also compared HPV using different perfusate solutions: Physiological salt solution (PSS) with albumin, Ficoll, rat blood, fetal bovine serum (FBS), or Dulbecco's Modified Eagle Medium (DMEM). After stabilization of the pulmonary arterial pressure (PAP), hypoxic (1% O2) and normoxic (21% O2) gases were applied via a ventilator in five-minute intervals to measure HPV. The addition of albumin or Ficoll with PSS did not induce persistent and strong HPV with or without a pretone agent. DMEM with the inclusion of FBS in the perfusate induced strong HPV in the first hypoxic challenge, but the HPV was neither persistent nor repetitive. PSS with rat blood only induced a small increase in HPV amplitude. Persistent and repetitive HPV occurred with PSS with 20% FBS as perfusate. HPV was significantly decreased by the removal of extracellular Ca2+ along with addition of 1 mM EGTA to chelate residual Ca2+ and voltage-dependent Ca2+ channel blocker (nifedipine 1 μM). PAP was also reactive to contractile stimulation by high K+ depolarization and U46619 (a stable analogue of thromboxane A2). In summary, optimal conditions for measuring HPV were established in the isolated perfused/ventilated mouse lung. Using this method, we further confirmed that HPV is dependent on Ca2+ influx.
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Affiliation(s)
- Hae Young Yoo
- Department of Medicine, Section of Pulmonary, Critical Care, Sleep and Allergy Medicine, University of Illinois at Chicago, Chicago, Illinois, USA
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14
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Blood AB, Terry MH, Merritt TA, Papamatheakis DG, Blood Q, Ross JM, Power GG, Longo LD, Wilson SM. Effect of chronic perinatal hypoxia on the role of rho-kinase in pulmonary artery contraction in newborn lambs. Am J Physiol Regul Integr Comp Physiol 2012; 304:R136-46. [PMID: 23152110 DOI: 10.1152/ajpregu.00126.2012] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Exposure to chronic hypoxia during gestation predisposes infants to neonatal pulmonary hypertension, but the underlying mechanisms remain unclear. Here, we test the hypothesis that moderate continuous hypoxia during gestation causes changes in the rho-kinase pathway that persist in the newborn period, altering vessel tone and responsiveness. Lambs kept at 3,801 m above sea level during gestation and the first 2 wk of life were compared with those with gestation at low altitude. In vitro studies of isolated pulmonary arterial rings found a more forceful contraction in response to KCl and 5-HT in high-altitude compared with low-altitude lambs. There was no difference between the effects of blockers of various pathways of extracellular Ca(2+) entry in low- and high-altitude arteries. In contrast, inhibition of rho-kinase resulted in significantly greater attenuation of 5-HT constriction in high-altitude compared with low-altitude arteries. High-altitude lambs had higher baseline pulmonary artery pressures and greater elevations in pulmonary artery pressure during 15 min of acute hypoxia compared with low-altitude lambs. Despite evidence for an increased role for rho-kinase in high-altitude arteries, in vivo studies found no significant difference between the effects of rho-kinase inhibition on hypoxic pulmonary vasoconstriction in intact high-altitude and low-altitude lambs. We conclude that chronic hypoxia in utero results in increased vasopressor response to both acute hypoxia and serotonin, but that rho-kinase is involved only in the increased response to serotonin.
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Affiliation(s)
- Arlin B Blood
- Department of Pediatrics, Division of Neonatology, Loma Linda University School of Medicine, Loma Linda, CA 92373, USA.
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15
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Hadley SR, Blood Q, Rubalcava M, Waskel E, Lumbard B, Le P, Longo LD, Buchholz JN, Wilson SM. Maternal high-altitude hypoxia and suppression of ryanodine receptor-mediated Ca2+ sparks in fetal sheep pulmonary arterial myocytes. Am J Physiol Lung Cell Mol Physiol 2012; 303:L799-813. [PMID: 22962012 DOI: 10.1152/ajplung.00009.2012] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Ca(2+) sparks are fundamental Ca(2+) signaling events arising from ryanodine receptor (RyR) activation, events that relate to contractile and dilatory events in the pulmonary vasculature. Recent studies demonstrate that long-term hypoxia (LTH) can affect pulmonary arterial reactivity in fetal, newborn, and adult animals. Because RyRs are important to pulmonary vascular reactivity and reactivity changes with ontogeny and LTH we tested the hypothesis that RyR-generated Ca(2+) signals are more active before birth and that LTH suppresses these responses. We examined these hypotheses by performing confocal imaging of myocytes in living arteries and by performing wire myography studies. Pulmonary arteries (PA) were isolated from fetal, newborn, or adult sheep that lived at low altitude or from those that were acclimatized to 3,801 m for > 100 days. Confocal imaging demonstrated preservation of the distance between the sarcoplasmic reticulum, nucleus, and plasma membrane in PA myocytes. Maturation increased global Ca(2+) waves and Ca(2+) spark activity, with sparks becoming larger, wider, and slower. LTH preferentially depressed Ca(2+) spark activity in immature pulmonary arterial myocytes, and these sparks were smaller, wider, and slower. LTH also suppressed caffeine-elicited contraction in fetal PA but augmented contraction in the newborn and adult. The influence of both ontogeny and LTH on RyR-dependent cell excitability shed new light on the therapeutic potential of these channels for the treatment of pulmonary vascular disease in newborns as well as adults.
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Affiliation(s)
- Scott R Hadley
- Center for Perinatal Biology, Loma Linda University, California 92350, USA
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