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Maternal toe perfusion index change after spinal anesthesia for cesarean delivery correlates with a decreased oxygen partial pressure of the umbilical vein. J Clin Anesth 2021; 75:110458. [PMID: 34274603 DOI: 10.1016/j.jclinane.2021.110458] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 07/03/2021] [Accepted: 07/07/2021] [Indexed: 11/20/2022]
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Djokic V, Jankovic S, Labudovic-Borovic M, Rakocevic J, Stanisic J, Rajkovic J, Novakovic R, Kostic M, Djuric M, Gostimirovic M, Gojkovic-Bukarica L. Pregnancy-induced hypertension decreases K v1.3 potassium channel expression and function in human umbilical vein smooth muscle. Eur J Pharmacol 2020; 882:173281. [PMID: 32562800 DOI: 10.1016/j.ejphar.2020.173281] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 06/09/2020] [Accepted: 06/15/2020] [Indexed: 10/24/2022]
Abstract
Voltage-gated potassium (Kv) channels are the largest superfamily of potassium (K) channels. A variety of Kv channels are expressed in the vascular smooth muscle cells (SMC). Studies have shown that gestational diabetes mellitus (GDM) and pregnancy-induced hypertension (PIH) cause various changes in the human umbilical vein (HUV). Recently, we have shown that 4-AP, a nonspecific Kv1-4 channel inhibitor, significantly decreases vasorelaxation induced by K channel opener pinacidil in vascular SMCs of the HUVs from normal pregnancies, but not in GDM and PIH. The goal of this study was to provide more detailed insight in the Kv channel subtypes involved in pinacidil-induced vasodilation of HUVs, as well as to investigate potential alterations of their function and expression during GDM and PIH. Margatoxin, a specific blocker of Kv1.2 and Kv1.3 channels, significantly antagonized pinacidil-induced vasorelaxation in normal pregnancy, while in HUVs from GDM and PIH that was not the case, indicating damage of Kv1.2 and Kv1.3 channel function. Immunohistochemistry and Western blot revealed similar expression of Kv1.2 channels in all groups. The expression of Kv1.3 subunit was significantly decreased in PIH, while it remained unchanged in GDM compared to normal pregnancy. Phrixotoxin, specific blocker of Kv4.2 and Kv4.3 channels, did not antagonize response to pinacidil in any of the groups. The major novel findings show that margatoxin antagonized pinacidil-induced relaxation in normal pregnancy, but not in GDM and PIH. Decreased expression of Kv1.3 channels in HUV during PIH may be important pathophysiological mechanism contributing to an increased risk of adverse pregnancy outcomes.
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Affiliation(s)
- Vladimir Djokic
- Department of Pharmacology, Clinical Pharmacology and Toxicology, Faculty of Medicine, University of Belgrade, 11000, Belgrade, Serbia.
| | - Svetlana Jankovic
- Department of Obstetrics and Gynecology "Narodni Front", Faculty of Medicine, University of Belgrade, 11000, Belgrade, Serbia
| | - Milica Labudovic-Borovic
- Institute of Histology and Embryology "Aleksandar Dj. Kostic", Faculty of Medicine, University of Belgrade, 11000, Belgrade, Serbia
| | - Jelena Rakocevic
- Institute of Histology and Embryology "Aleksandar Dj. Kostic", Faculty of Medicine, University of Belgrade, 11000, Belgrade, Serbia
| | - Jelena Stanisic
- Vinca Institute of Nuclear Sciences, 11000, Belgrade, Serbia
| | - Jovana Rajkovic
- Department of Pharmacology, Clinical Pharmacology and Toxicology, Faculty of Medicine, University of Belgrade, 11000, Belgrade, Serbia
| | - Radmila Novakovic
- Department of Pharmacology, Clinical Pharmacology and Toxicology, Faculty of Medicine, University of Belgrade, 11000, Belgrade, Serbia
| | - Milan Kostic
- Vinca Institute of Nuclear Sciences, 11000, Belgrade, Serbia
| | - Milos Djuric
- Department of Pharmacology, Clinical Pharmacology and Toxicology, Faculty of Medicine, University of Belgrade, 11000, Belgrade, Serbia
| | - Milos Gostimirovic
- Department of Pharmacology, Clinical Pharmacology and Toxicology, Faculty of Medicine, University of Belgrade, 11000, Belgrade, Serbia
| | - Ljiljana Gojkovic-Bukarica
- Department of Pharmacology, Clinical Pharmacology and Toxicology, Faculty of Medicine, University of Belgrade, 11000, Belgrade, Serbia
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Djokic V, Jankovic-Raznatovic S, Novakovic R, Kostic M, Rajkovic J, Labudovic-Borovic M, Rakocevic J, Stanisic J, Djuric M, Gojkovic-Bukarica L. Effect of gestational diabetes mellitus and pregnancy-induced hypertension on human umbilical vein smooth muscle K ATP channels. Exp Mol Pathol 2019; 111:104323. [PMID: 31669131 DOI: 10.1016/j.yexmp.2019.104323] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Revised: 09/03/2019] [Accepted: 10/21/2019] [Indexed: 01/25/2023]
Abstract
Gestational diabetes mellitus (GDM) and pregnancy-induced hypertension (PIH) can jeopardize mother and/or fetus. Vascular ATP-sensitive potassium (KATP) channels most likely participate in the processes of diabetes and hypertension. The aim of this research was to examine whether GDM and PIH cause changes in the expression and function of KATP channels in vascular smooth muscle of human umbilical vein (HUV). Western blot and immunohistochemistry detected significantly decreased expression of Kir6.1 subunit of KATP channels in GDM and PIH, while the expression of SUR2B was unchanged. In GDM, a K+ channel opener, pinacidil caused reduced relaxation of the endothelium-denuded HUVs compared to normal pregnancy. However, its effects in HUVs from PIH subjects were similar to normal pregnancy. In all groups KATP channel blocker glibenclamide antagonized the relaxation of HUV induced by pinacidil without change in the maximal relaxations indicating additional KATP channel-independent mechanisms of pinacidil action. Iberiotoxin, a selective antagonist of large-conductance calcium-activated potassium channels, inhibited the relaxant effect of pinacidil in PIH, but not in normal pregnancy and GDM. Experiments performed in K+-rich solution confirmed the existence of K+-independent effects of pinacidil, which also appear to be impaired in GDM and PIH. Thus, the expression of KATP channels is decreased in GDM and PIH. In GDM, vasorelaxant response of HUV to pinacidil is reduced, while in PIH it remains unchanged. It is very likely that KATP channels modulation and more detailed insight in KATP channel-independent actions of pinacidil may be precious in the therapy of pathological pregnancies.
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Affiliation(s)
- Vladimir Djokic
- Department of Pharmacology, Clinical Pharmacology and Toxicology, Faculty of Medicine, University of Belgrade, 11000 Belgrade, Serbia.
| | - Svetlana Jankovic-Raznatovic
- Department of Obstetrics and Gynecology "Narodni front", Faculty of Medicine, University of Belgrade, 11000 Belgrade, Serbia
| | - Radmila Novakovic
- Department of Pharmacology, Clinical Pharmacology and Toxicology, Faculty of Medicine, University of Belgrade, 11000 Belgrade, Serbia
| | - Milan Kostic
- Vinca Institute of Nuclear Sciences, 11000 Belgrade, Serbia
| | - Jovana Rajkovic
- Department of Pharmacology, Clinical Pharmacology and Toxicology, Faculty of Medicine, University of Belgrade, 11000 Belgrade, Serbia
| | - Milica Labudovic-Borovic
- Institute of Histology and Embryology "Aleksandar Dj. Kostic", Faculty of Medicine, University of Belgrade, 11000 Belgrade, Serbia
| | - Jelena Rakocevic
- Institute of Histology and Embryology "Aleksandar Dj. Kostic", Faculty of Medicine, University of Belgrade, 11000 Belgrade, Serbia
| | | | - Milos Djuric
- Department of Pharmacology, Clinical Pharmacology and Toxicology, Faculty of Medicine, University of Belgrade, 11000 Belgrade, Serbia
| | - Ljiljana Gojkovic-Bukarica
- Department of Pharmacology, Clinical Pharmacology and Toxicology, Faculty of Medicine, University of Belgrade, 11000 Belgrade, Serbia
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Hypoxia is an effective stimulus for vesicular release of ATP from human umbilical vein endothelial cells. Placenta 2015; 36:759-66. [PMID: 25956988 PMCID: PMC4502406 DOI: 10.1016/j.placenta.2015.04.005] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Revised: 03/26/2015] [Accepted: 04/09/2015] [Indexed: 12/12/2022]
Abstract
Introduction Hypoxia induces dilatation of the umbilical vein by releasing autocoids from endothelium; prostaglandins (PGs), adenosine and nitric oxide (NO) have been implicated. ATP is vasoactive, thus we tested whether hypoxia releases ATP from primary Human Umbilical Vein Endothelial Cells (HUVEC). Methods HUVEC were grown on inserts under no-flow conditions. ATP was assayed by luciferin–luciferase and visualised by quinacrine labeling. Intracellular Ca2+ ([Ca2+]i) was imaged with Fura-2. Results ATP release occurred constitutively and was increased by hypoxia (PO2: 150–8 mmHg), ∼10-fold more from apical, than basolateral surface. Constitutive ATP release was decreased, while hypoxia-induced release was abolished by brefeldin or monensin A, inhibitors of vesicular transport, and LY294002 or Y27632, inhibitors of phosphoinositide 3-kinases (PI3K) and Rho-associated protein kinase (ROCK). ATP release was unaffected by NO donor, but increased by calcium ionophore, by >60-fold from apical, but <25% from basolateral surface. Hypoxia induced a small increase in [Ca2+]i compared with ATP (10 μM); hypoxia inhibited the ATP response. Quinacrine-ATP fluorescent loci in the perinuclear space, were diminished by hypoxia and monensin, whereas brefeldin A increased fluorescence intensity, consistent with inhibition of anterograde transport. Discussion. Hypoxia within the physiological range releases ATP from HUVEC, particularly from apical/adluminal surfaces by exocytosis, via an increase in [Ca2+]i, PI3K and ROCK, independently of NO. We propose that hypoxia releases ATP at concentrations sufficient to induce umbilical vein dilation via PGs and NO and improve fetal blood flow, but curbs amplification of ATP release by autocrine actions of ATP, so limiting its pro-inflammatory effects. Hypoxia releases ATP from Human umbilical vein endothelial cells (HUVEC). This ATP release is preferentially from apical surfaces. Polarised ATP release is also triggered by Ca2+ ionophore. Hypoxia-induced ATP release occurs from vesicles, as visualised by quinacrine. It is attenuated by inhibitors of vesicular trafficking, PI3K and ROCK.
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Nyberg MK, Johnsen SL, Rasmussen S, Kiserud T. Fetal breathing is associated with increased umbilical blood flow. ULTRASOUND IN OBSTETRICS & GYNECOLOGY : THE OFFICIAL JOURNAL OF THE INTERNATIONAL SOCIETY OF ULTRASOUND IN OBSTETRICS AND GYNECOLOGY 2010; 36:718-723. [PMID: 20521237 DOI: 10.1002/uog.7701] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 05/20/2010] [Indexed: 05/29/2023]
Abstract
OBJECTIVES In humans, fetal breathing movements affect blood velocities in the umbilical vein and artery, but it is not known whether fetal respiratory activity is associated with increased fetal blood flow through the placenta. We therefore tested this hypothesis in the present study. METHODS One-hundred and ten women with low-risk singleton pregnancies were each examined three times by ultrasound during the second half of pregnancy. Fetal heart rate, umbilical artery blood velocity, umbilical vein diameter and blood velocity, and umbilical blood flow at the placental end were determined during fetal rest and fetal respiratory movements. RESULTS Based on 330 observations obtained during fetal rest or breathing activity, no difference was found in the mean fetal heart rate (beats per minute (bpm)) during rest compared with breathing (142 bpm vs. 142 bpm, respectively). Although fetal breathing affected the umbilical artery waveform, there was no difference in the mean time-averaged maximum velocity between rest and breathing: 26.6 (95% CI, 25.1-28.3) cm/s vs. 28.9 (95% CI, 27.2-30.7) cm/s, respectively. The umbilical vein was 27% greater in cross-sectional area and the blood velocity 9% higher during breathing, resulting in a 42% increase in mean umbilical blood flow: 121.8 (95% CI, 109.5-135.0) mL/min at rest vs. 173.0 (95% CI, 158.0-188.6) mL/min during breathing. Venous velocity was calculated from recordings of mean duration 3.7 s at rest and 6.2 s of respiratory activity. Gestational age did not influence the relationship. CONCLUSION Fetal breathing is associated with increased umbilical blood flow during the second half of pregnancy. Umbilical vein distension during breathing suggests active endocrine regulation.
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Affiliation(s)
- M K Nyberg
- Department of Clinical Medicine, University of Bergen, Bergen, Norway.
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Morris DM, Ross JAS, McVicar A, Semple SIK, Haggarty P, Gilbert FJ, Abramovich DR, Smith N, Redpath TW. Changes in foetal liver T2* measurements by MRI in response to maternal oxygen breathing: application to diagnosing foetal growth restriction. Physiol Meas 2010; 31:1137-46. [DOI: 10.1088/0967-3334/31/9/005] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Mildenberger E, Biesel B, Siegel G, Versmold HT. Endothelin B Receptors on Vascular Smooth Muscle Cells of the Human Umbilical Vein Mediate Vasoconstriction. Fetal Diagn Ther 2008; 24:67-70. [DOI: 10.1159/000132410] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2007] [Accepted: 04/22/2007] [Indexed: 11/19/2022]
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García-Huidobro DN, García-Huidobro MT, Huidobro-Toro JPG. Vasomotion in Human Umbilical and Placental Veins: Role of Gap Junctions and Intracellular Calcium Reservoirs in Their Synchronous Propagation. Placenta 2007; 28:328-38. [PMID: 16797694 DOI: 10.1016/j.placenta.2006.04.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2006] [Revised: 04/13/2006] [Accepted: 04/14/2006] [Indexed: 11/20/2022]
Abstract
Vasomotion was characterized using human placentae vessel rings; force displacement transducers recorded isometric contractions. Umbilical vein rings display rhythmic contractions occurring with a frequency of 1.47+/-0.01 min(-1) and 274+/-2.2 mg (n=211) of amplitude, which corresponds to 11.1+/-0.4% of the maximal KCl contracture. Vasomotion waves were recorded for up to 8 h; their amplitude and duration was larger in umbilical veins than arteries or chorionic vessels (p<0.001), vasomotion frequency was indistinguishable among these vessels. Segments of the umbilical vein closer to the fetus showed larger amplitudes and longer-lasting waves. Gap junction blockers, including peptide Gap 27, 18alpha-glycyrrhetinic acid, hexanol, heptanol or octanol, reduced the amplitude but not the frequency of vasomotion; all these drugs, in addition, decreased tissue basal tension. The role of intracellular calcium stores was evidenced using calcium-free buffer, which reduced oscillation amplitude and tissue basal tension. Cyclopiazonic acid increased wave amplitude and tissue basal tension, reducing oscillatory frequency. We propose that biological oscillators localized in the smooth muscle layer of the umbilical cord, trigger vasomotion waves, which are synchronized and propagated via gap junctions; internal calcium reservoirs are essential for their maintenance. These myogenic oscillations may be relevant for maternal-fetus blood flow and contribute to fetal nutrition and development.
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Affiliation(s)
- Diego Nicolás García-Huidobro
- Centro de Regulación Celular y Patología J.V. Luco, Instituto Investigación Fundamental y Aplicada, MIFAB, Departamento de Fisiología, Unidad de Regulación Neurohumoral, P. Universidad Católica de Chile, Santiago 1 6513492, Chile
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San Martín R, Sobrevia L. Gestational diabetes and the adenosine/L-arginine/nitric oxide (ALANO) pathway in human umbilical vein endothelium. Placenta 2006; 27:1-10. [PMID: 16310032 DOI: 10.1016/j.placenta.2005.01.011] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2004] [Revised: 01/18/2005] [Accepted: 01/20/2005] [Indexed: 01/22/2023]
Abstract
Altered endothelial cell function is a key factor associated with vascular disorders and is critical in the fetal growth and development. Pregnancies affected by diseases such as gestational diabetes are associated with human umbilical vein endothelial dysfunction, a finding that has been associated with a high incidence of vascular complications during the adult life. Limited information is available addressing cellular mechanisms associated with altered human umbilical vein endothelial function in gestational diabetes. One of the key signalling pathways associated with altered vascular physiology is the synthesis of the vasodilator nitric oxide (NO) from the cationic amino acid L-arginine by the endothelium (i.e. the endothelial L-arginine/NO pathway). The activity of this signalling pathway is modulated by D-glucose, adenosine, insulin, and ATP, among other molecules, and is upregulated (transcriptional, post-transcriptional and post-translational levels) in gestational diabetes. This review focuses on the cellular and molecular mechanisms involved with elevated adenosine levels in fetal umbilical vein blood and the endothelial L-arginine/NO pathway activity in gestational diabetes. We suggest that a lower capacity of adenosine transport by the fetal endothelium in gestational diabetes leads to extracellular accumulation of this nucleoside and its higher bio-availability activates endothelial P1 type purinoceptors. A functional association between A2a purinoceptor subtype signalling and the activity of the l-arginine transport mediated by human cationic amino acid transporters and endothelial NO synthase activity (i.e. 'ALANO pathway') is proposed, revealing in part the mechanisms that account for human umbilical vein endothelial cell dysfunction programmed through the development of the fetus in gestational diabetes.
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Affiliation(s)
- R San Martín
- Cellular and Molecular Physiology Laboratory (CMPL), Department of Obstetrics and Gynaecology, Medical Research Centre (CIM), School of Medicine, Faculty of Medicine, Pontificia Universidad Católica de Chile, P.O. Box 114-D, Santiago, Chile
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Trampont P, Roudier M, Andrea AM, Nomal N, Mignot TM, Leborgne-Samuel Y, Ravion S, Clayton J, Mary D, Elion J, Decastel M. The placental-umbilical unit in sickle cell disease pregnancy: A model for studying in vivo functional adjustments to hypoxia in humans. Hum Pathol 2004; 35:1353-9. [PMID: 15668892 DOI: 10.1016/j.humpath.2004.07.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The placental-umbilical unit in sickle cell disease (SCD) pregnancy was used to explore hypoxia in vivo, an important factor in the pathophysiology of this disease. Gross examination and microscopic analysis of the placentas, taken immediately after delivery, indicate good concordance between maturity and term as controls, but higher frequency of vascular injuries such as excess syncytial knots, excess fibrin deposits, congestion and villous necroses. Unexpectedly, neither leukocyte recruitment nor alteration in extraplacental membrane was observed, suggesting the absence of inflammation. Additionally, interleukin (IL)-6 and IL-8 concentrations, measured by enzyme-linked immunosorbent assay (ELISA), were similar in the placental maternal blood from controls and SCD. There were also no significant differences found in IL-6 vein blood concentrations between controls and SCD, IL-8 being not detected. Immunostaining of umbilical vein endothelium in SCD pregnancies showed redistribution of PECAM-1 (CD31), von Willebrand factor (vWF), and P-selectin to the cell surface, controls exhibiting the classical pattern. Staining quantification indicated increases in vWF (+36.2%; P=.006) and vascular endothelial growth factor (VEGF) expression (+96.0%; P=.006) over control, but a reduction in endothelial nitric oxide synthase (eNOS) (-45.5%; P=.029). These results document, for the first time, direct functional adjustments in response to hypoxia in human in vivo. The mechanism for these changes has not been clearly established, but it may reflect increased tolerance to SCD hypoxic conditions and hypoxia in general.
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Affiliation(s)
- Paul Trampont
- UMR-S458 INSERM Université des Antilles et de la Guyane, Paris, France
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Mildenberger E, Siegel G, Versmold HT. Locally released norepinephrine in the oxygen-dependent regulation of vascular tone of human umbilical vein. Pediatr Res 2004; 55:267-72. [PMID: 14605241 DOI: 10.1203/01.pdr.0000100907.68842.a7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
In a previous study, human umbilical vein preparations constricted at PO(2) values above the physiologic intrauterine PO(2) range and dilated at hypoxia. Denudation of the endothelium reversed the hypoxic vasodilatation only, suggesting the release of a nonendothelial vasoconstrictor. We therefore hypothesized that norepinephrine from adrenergic nerve terminals could be responsible for the observed constricting effects. We measured intracellular membrane potential and isometric tension of human umbilical vein strips with and without functional adrenergic denervation by 6-OH-dopamine during variation of PO(2). With PO(2) increasing from 5 to 104 mm Hg, intact preparations depolarized of from -58.6 +/- 1.1 mV (SEM) to -53.3 +/- 1.0 mV (p < 0.001) and isometric tension increased from 0.673 +/- 0.037 g to 0.825 +/- 0.044 g (p < 0.02). Intact preparations pretreated with 6-OH-dopamine depolarized from -58.0 +/- 0.5 mV to -55.8 +/- 0.6 mV (p < 0.01), and isometric tension increased from 0.598 +/- 0.040 g to 0.661 +/- 0.018 g (p < 0.02). At Po(2) values above the physiologic intrauterine umbilical venous Po(2) range, membrane potential and isometric tension were significantly lower in preparations with 6-OH-dopamine pretreatment compared with matched controls (p < 0.05). Denudation of the endothelium reversed the hypoxic hyperpolarization and vasodilatation observed in intact preparations. However, membrane potential and isometric tension were not different between endothelium-denuded preparations with and without 6-OH-dopamine pretreatment. We conclude that locally released norepinephrine contributes to the depolarization and vasoconstriction of the human umbilical vein at hyperoxia but does not antagonize the endothelium-dependent vasodilation at hypoxia.
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Affiliation(s)
- Eva Mildenberger
- Department of Pediatrics, Universitätsklinikum Benjamin Franklin, Freie Universität, 12200 Berlin, Germany.
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Mildenberger E, Biesel B, Siegel G, Versmold HT. Nitric oxide and endothelin in oxygen-dependent regulation of vascular tone of human umbilical vein. Am J Physiol Heart Circ Physiol 2003; 285:H1730-7. [PMID: 12969885 DOI: 10.1152/ajpheart.00938.2002] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We investigated the possible contribution of nitric oxide (NO) and endothelin (ET) to oxygen-dependent regulation of human umbilical vein vascular tone by simultaneous registration of intracellular membrane potential and isometric tension of vessel strips with and without NO synthase inhibition [10-4 M N omega-nitro-L-arginine methyl ester (L-NAME)], ETA receptor blockade (10(-5) M BQ-123), or ETB receptor blockade (10(-7) M BQ-788) at Po2 values in the bath solution between 5 and 104 mmHg. Increasing PO2 above the physiological intrauterine range resulted in depolarization and an increase of isometric tension, whereas lowering PO2 resulted in hyperpolarization and a decrease in isometric tension. Removal of the endothelium reversed these effects. At PO2 values below 39 mmHg, intact preparations treated with either L-NAME, BQ-788, or BQ-123 were more depolarized than controls. In the case of treatment with L-NAME or BQ-123, this was accompanied by an increase in isometric tension. We conclude that it is NO that mediates the hypoxic hyperpolarization and vasodilatation of the human umbilical vein and that ET, via activation of ETB1 receptors on endothelial cells, contributes to this effect.
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Affiliation(s)
- Eva Mildenberger
- Department of Pediatrics, Universitätsklinikum Benjamin Franklin, Freie Universität Berlin, Hindenburgdamm 30, 12200 Berlin, Germany.
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Hoehn T, Felderhoff U, Altstaedt J, Obladen M, Bührer C. Hyperoxia- and hypoxia-mediated activation of polymorphonuclear leukocytes: a comparison of cord and adult venous blood. Resuscitation 2001; 51:63-8. [PMID: 11719175 DOI: 10.1016/s0300-9572(01)00375-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Among the most prominent changes occurring in newborn infants is the exposure of tissues and blood cells to increased oxygen tension. This increase is even more pronounced in neonatal resuscitation using 100% oxygen, currently recommended in the published guidelines. OBJECTIVE To analyse the response of neonatal and adult polymorphonuclear neutrophils (PMN) to high or low oxygen tension in vitro. MATERIALS Neonatal cord blood and adult venous blood without previous contact to ambient air was exposed to 0, 21, or 100% oxygen for 30 min followed by incubation for up to 24 h. METHODS Flow cytometry was used to assess PMN activation as indicated by downregulation of L-selectin expression. Cell viability was quantified by the amount of propidium iodide uptake. RESULTS In adult PMN, L-selectin downregulation was greatly accelerated by hypoxia (PO2=27.2+/-3.4 mmHg) compared with both normoxia (PO2=71.0+/-11.0 mmHg) or hyperoxia (PO2=653.2+/-9.4) (P<0.05). In contrast, hyperoxia was the most potent stimulus for cord blood PMN, compared with both normoxia and hypoxia (P<0.05). Evidence of necrosis as indicated by positive staining for propidium iodide was similar in cord blood (10 h: 5.83% in oxygen) and in adult blood (10 h: 6.45% in oxygen). No differences were found between exposure to hypoxia, normoxia, or hyperoxia. CONCLUSION Oxygen exposure of neonatal PMN leads to a more pronounced activation as compared with adult cells. Exposure towards high concentrations of oxygen may contribute to inflammatory processes during early neonatal life.
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Affiliation(s)
- T Hoehn
- Department of Neonatology, Humboldt University, Charité, Campus Virchow Hospital, Augustenburger Platz 1, 13353, Berlin, Germany.
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