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Cho S, Oh SB, Kim HJ, Kim SJ. T18/S19 diphosphorylation of myosin regulatory light chain impairs pulmonary artery relaxation in monocrotaline-induced pulmonary hypertensive rats. Pflugers Arch 2023; 475:1097-1112. [PMID: 37422604 DOI: 10.1007/s00424-023-02836-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 04/29/2023] [Accepted: 06/26/2023] [Indexed: 07/10/2023]
Abstract
Phosphorylation of Ser19 (S19-p) on the myosin regulatory light chain (MLC2) is critical for arterial contraction. It has been shown that elevated RhoA-dependent kinase (ROCK) activity or decreased MLC phosphatase (MLCP) activity leads to further phosphorylation of Thr18 (T18/S19-pp), which has been linked to vasospastic diseases. However, this phenomenon has not yet been studied in the context of pulmonary arterial hypertension (PAH). In the monocrotaline-induced PAH (PAH-MCT) rat model, we observed a significant delay in pulmonary artery (PA) relaxation following high potassium-induced contraction, which persisted even with the use of an L-type calcium channel blocker or in a calcium-free solution. Immunoblot analysis showed increased levels of both S19-p and T18/S19-pp in unstimulated PAs from PAH-MCT rats. Proteomics analysis revealed a reduction in soluble guanylate cyclase (sGC) and protein kinase G (PKG) levels, and immunoblotting confirmed decreased levels of MYPT1 (a component of MLCP) and increased ROCK in PAH-MCT. In the control PAs, the pharmacological inhibition of sGC with ODQ resulted in a prominent delay of relaxation and increased T18/S19-pp as in PAH-MCT. The delayed relaxation and the T18/S19-pp in PAH-MCT were reversed by ROCK inhibitor, Y27632, while not by membrane permeable 8-Br-cGMP. The delayed relaxation and T18/S19-diP in the ODQ-treated control PA were also reversed by Y27632. Taken together, the decreased sGC and MLCP, and increased ROCK increased T18/S19-pp, which leads to the decreased ability of PA to relax in PAH-MCT rats. PA specific inhibition of ROCK or activation of MLCP are expected to serve as potential drugs in the treatment of PAH.
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Affiliation(s)
- Suhan Cho
- Department of Physiology, Seoul National University College of Medicine, Seoul, 03080, South Korea
| | - Seung Beom Oh
- Department of Physiology, Seoul National University College of Medicine, Seoul, 03080, South Korea
| | - Hae Jin Kim
- Department of Physiology, Seoul National University College of Medicine, Seoul, 03080, South Korea
- Ischemic/Hypoxic Disease Institute, Seoul National University College of Medicine, Seoul, 03080, South Korea
- Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, MO, Columbia, USA
| | - Sung Joon Kim
- Department of Physiology, Seoul National University College of Medicine, Seoul, 03080, South Korea.
- Ischemic/Hypoxic Disease Institute, Seoul National University College of Medicine, Seoul, 03080, South Korea.
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2
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Prim DA, Lane BA, Ferruzzi J, Shazly T, Eberth JF. Evaluation of the Stress-Growth Hypothesis in Saphenous Vein Perfusion Culture. Ann Biomed Eng 2020; 49:487-501. [PMID: 32728831 DOI: 10.1007/s10439-020-02582-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Accepted: 07/22/2020] [Indexed: 01/02/2023]
Abstract
The great saphenous vein (GSV) has served as a coronary artery bypass graft (CABG) conduit for over 50 years. Despite prevalent use, first-year failure rates remain high compared to arterial autograft options. Amongst other factors, vein graft failure can be attributed to material and mechanical mismatching that lead to apoptosis, inflammation, and intimal-medial hyperplasia. Through the implementation of the continuum mechanical-based theory of "stress-mediated growth and remodeling," we hypothesize that the mechanical properties of porcine GSV grafts can be favorably tuned for CABG applications prior to implantation using a prolonged but gradual transition from venous to arterial loading conditions in an inflammatory and thrombogenic deficient environment. To test this hypothesis, we used a hemodynamic-mimetic perfusion bioreactor to guide remodeling through stepwise incremental changes in pressure and flow over the course of 21-day cultures. Biaxial mechanical testing of vessels pre- and post-remodeling was performed, with results fit to structurally-motivated constitutive models using non-parametric bootstrapping. The theory of "small-on-large" was used to describe appropriate stiffness moduli, while histology and viability assays confirmed microstructural adaptations and vessel viability. Results suggest that stepwise transition from venous-to-arterial conditions results in a partial restoration of circumferential stretch and circumferential, but not axial, stress through vessel dilation and wall thickening in a primarily outward remodeling process. These remodeled tissues also exhibited decreased mechanical isotropy and circumferential, but not axial, stiffening. In contrast, only increases in axial stiffness were observed using culture under venous perfusion conditions and those tissues experienced moderate intimal resorption.
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Affiliation(s)
- David A Prim
- Biomedical Engineering Program, University of South Carolina, Columbia, SC, USA
| | - Brooks A Lane
- Biomedical Engineering Program, University of South Carolina, Columbia, SC, USA
| | - Jacopo Ferruzzi
- Biomedical Engineering Department, Boston University, Boston, MA, USA
| | - Tarek Shazly
- Biomedical Engineering Program, University of South Carolina, Columbia, SC, USA.,Mechanical Engineering Department, University of South Carolina, Columbia, SC, USA
| | - John F Eberth
- Biomedical Engineering Program, University of South Carolina, Columbia, SC, USA. .,Cell Biology and Anatomy Department (CBA), SOM, University of South Carolina (USC), Bldg.1, Rm. C-36, Columbia, SC, 29208, USA.
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3
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B Ramachandra A, Humphrey JD. Biomechanical characterization of murine pulmonary arteries. J Biomech 2019; 84:18-26. [PMID: 30598195 PMCID: PMC6361676 DOI: 10.1016/j.jbiomech.2018.12.012] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Revised: 11/11/2018] [Accepted: 12/05/2018] [Indexed: 12/20/2022]
Abstract
The biomechanical properties of the major pulmonary arteries play critical roles in normal physiology as well as in diverse pathophysiologies and clinical interventions. Importantly, advances in medical imaging enable simulations of pulmonary hemodynamics, but such models cannot reach their full potential until they are informed with region-specific material properties. In this paper, we present passive and active biaxial biomechanical data for the right and left main pulmonary arteries from wild-type mice. We also evaluate the suitability of a four-fiber family constitutive model as a descriptor of the passive behavior. Despite regional differences in size, the biaxial mechanical properties, including passive stiffness and elastic energy storage, the biaxial wall stresses at in vivo pressures, and the overall contractile capacity in response to smooth muscle cell stimulation under in vivo conditions are remarkably similar between the right and left branches. The proposed methods and results can serve as baseline protocols and measurements for future biaxial experiments on murine models of pulmonary pathologies, and the constitutive model can inform computational models of normal pulmonary growth and remodeling. Our use of consistent experimental protocols and data analyses can also facilitate comparative studies in health and disease across the systemic and pulmonary circulations as well as studies seeking to understand remodeling in surgeries such as the Fontan procedure, which involves different types of vessels.
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Affiliation(s)
- Abhay B Ramachandra
- Department of Biomedical Engineering, Yale University, New Haven, CT, United States
| | - Jay D Humphrey
- Department of Biomedical Engineering, Yale University, New Haven, CT, United States; Vascular Biology and Therapeutics Program, Yale School of Medicine, New Haven, CT, United States.
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4
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Stenmark KR, Nozik-Grayck E, Gerasimovskaya E, Anwar A, Li M, Riddle S, Frid M. The adventitia: Essential role in pulmonary vascular remodeling. Compr Physiol 2013; 1:141-61. [PMID: 23737168 DOI: 10.1002/cphy.c090017] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
A rapidly emerging concept is that the vascular adventitia acts as a biological processing center for the retrieval, integration, storage, and release of key regulators of vessel wall function. It is the most complex compartment of the vessel wall and comprises a variety of cells including fibroblasts, immunomodulatory cells, resident progenitor cells, vasa vasorum endothelial cells, and adrenergic nerves. In response to vascular stress or injury, resident adventitial cells are often the first to be activated and reprogrammed to then influence tone and structure of the vessel wall. Experimental data indicate that the adventitial fibroblast, the most abundant cellular constituent of adventitia, is a critical regulator of vascular wall function. In response to vascular stresses such as overdistension, hypoxia, or infection, the adventitial fibroblast is activated and undergoes phenotypic changes that include proliferation, differentiation, and production of extracellular matrix proteins and adhesion molecules, release of reactive oxygen species, chemokines, cytokines, growth factors, and metalloproteinases that, collectively, affect medial smooth muscle cell tone and growth directly and that stimulate recruitment and retention of circulating inflammatory and progenitor cells to the vessel wall. Resident dendritic cells also participate in "sensing" vascular stress and actively communicate with fibroblasts and progenitor cells to simulate repair processes that involve expansion of the vasa vasorum, which acts as a conduit for further delivery of inflammatory/progenitor cells. This review presents the current evidence demonstrating that the adventitia acts as a key regulator of pulmonary vascular wall function and structure from the "outside in."
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Affiliation(s)
- Kurt R Stenmark
- University of Colorado Denver - Pediatric Critical Care, Aurora, Colorado, USA.
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5
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The role of pulmonary vascular contractile protein expression in pulmonary arterial hypertension. J Mol Cell Cardiol 2013; 65:147-55. [PMID: 24161910 DOI: 10.1016/j.yjmcc.2013.10.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Revised: 09/30/2013] [Accepted: 10/15/2013] [Indexed: 12/13/2022]
Abstract
Pulmonary arterial hypertension (PAH) is associated with refractory vasoconstriction and impaired NO-mediated vasodilatation of the pulmonary vasculature. Vascular tone is regulated by light chain (LC) phosphorylation of both nonmuscle (NM) and smooth muscle (SM) myosins, which are determined by the activities of MLC kinase and MLC phosphatase. Further, NO mediated vasodilatation requires the expression of a leucine zipper positive (LZ+) isoform of the myosin targeting subunit (MYPT1) of MLC phosphatase. The objective of this study was to define contractile protein expression in the pulmonary arterial vasculature and vascular reactivity in PAH. In severe PAH, compared to controls, relative LZ+MYPT1 expression was decreased (100 ± 14% vs. 60 ± 6%, p<0.05, n=7-8), and NM myosin expression was increased (1 5 ± 4% vs. 53 ± 5% of total myosin, p<0.05, n=4-6). These changes in contractile protein expression should alter vascular reactivity; following activation with Ang II, force activation and relaxation were slowed, and sustained force was increased. Further, the sensitivity to ACh-mediated relaxation was reduced. These results demonstrate that changes in the pulmonary arterial SM contractile protein expression may participate in the molecular mechanism producing both the resting vasoconstriction and the decreased sensitivity to NO-mediated vasodilatation associated with PAH.
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6
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Stenmark KR, Yeager ME, El Kasmi KC, Nozik-Grayck E, Gerasimovskaya EV, Li M, Riddle SR, Frid MG. The adventitia: essential regulator of vascular wall structure and function. Annu Rev Physiol 2012; 75:23-47. [PMID: 23216413 PMCID: PMC3762248 DOI: 10.1146/annurev-physiol-030212-183802] [Citation(s) in RCA: 267] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The vascular adventitia acts as a biological processing center for the retrieval, integration, storage, and release of key regulators of vessel wall function. It is the most complex compartment of the vessel wall and is composed of a variety of cells, including fibroblasts, immunomodulatory cells (dendritic cells and macrophages), progenitor cells, vasa vasorum endothelial cells and pericytes, and adrenergic nerves. In response to vascular stress or injury, resident adventitial cells are often the first to be activated and reprogrammed to influence the tone and structure of the vessel wall; to initiate and perpetuate chronic vascular inflammation; and to stimulate expansion of the vasa vasorum, which can act as a conduit for continued inflammatory and progenitor cell delivery to the vessel wall. This review presents the current evidence demonstrating that the adventitia acts as a key regulator of vascular wall function and structure from the outside in.
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Affiliation(s)
- Kurt R. Stenmark
- University of Colorado Denver, Division of Pediatric Critical Care, Aurora, CO 80045
| | - Michael E. Yeager
- University of Colorado Denver, Division of Pediatric Critical Care, Aurora, CO 80045
| | - Karim C. El Kasmi
- University of Colorado Denver, Division of Pediatric Critical Care, Aurora, CO 80045
| | - Eva Nozik-Grayck
- University of Colorado Denver, Division of Pediatric Critical Care, Aurora, CO 80045
| | | | - Min Li
- University of Colorado Denver, Division of Pediatric Critical Care, Aurora, CO 80045
| | - Suzette R. Riddle
- University of Colorado Denver, Division of Pediatric Critical Care, Aurora, CO 80045
| | - Maria G. Frid
- University of Colorado Denver, Division of Pediatric Critical Care, Aurora, CO 80045
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7
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Chettimada S, Rawat DK, Dey N, Kobelja R, Simms Z, Wolin MS, Lincoln TM, Gupte SA. Glc-6-PD and PKG contribute to hypoxia-induced decrease in smooth muscle cell contractile phenotype proteins in pulmonary artery. Am J Physiol Lung Cell Mol Physiol 2012; 303:L64-74. [PMID: 22582112 DOI: 10.1152/ajplung.00002.2012] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Persistent hypoxic pulmonary vasoconstriction (HPV) plays a significant role in the pathogenesis of pulmonary hypertension, which is an emerging clinical problem around the world. We recently showed that hypoxia-induced activation of glucose-6-phosphate dehydrogenase (Glc-6-PD) in pulmonary artery smooth muscle links metabolic changes within smooth muscle cells to HPV and that inhibition of Glc-6PD reduces acute HPV. Here, we demonstrate that exposing pulmonary arterial rings to hypoxia (20-30 Torr) for 12 h in vitro significantly (P < 0.05) reduces (by 30-50%) SM22α and smooth muscle myosin heavy chain expression and evokes HPV. Glc-6-PD activity was also elevated in hypoxic pulmonary arteries. Inhibition of Glc-6-PD activity prevented the hypoxia-induced reduction in SM22α expression and inhibited HPV by 80-90% (P < 0.05). Furthermore, Glc-6-PD and protein kinase G (PKG) formed a complex in pulmonary artery, and Glc-6-PD inhibition increased PKG-mediated phosphorylation of VASP (p-VASP). In turn, increasing PKG activity upregulated SM22α expression and attenuated HPV evoked by Glc-6-PD inhibition. Increasing passive tension (from 0.8 to 3.0 g) in hypoxic arteries for 12 h reduced Glc-6-PD, increased p-VASP and SM22α levels, and inhibited HPV. The present findings indicate that increases in Glc-6-PD activity influence PKG activity and smooth muscle cell phenotype proteins, all of which affect pulmonary artery contractility and remodeling.
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Affiliation(s)
- Sukrutha Chettimada
- Department of Biochemistry & Molecular Biology, College of Medicine, University of South Alabama, Mobile, AL 36688, USA
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8
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Stenmark KR, Davie N, Frid M, Gerasimovskaya E, Das M. Role of the adventitia in pulmonary vascular remodeling. Physiology (Bethesda) 2006; 21:134-45. [PMID: 16565479 DOI: 10.1152/physiol.00053.2005] [Citation(s) in RCA: 174] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
An increasing volume of experimental data indicates that the adventitial fibroblast, in both the pulmonary and systemic circulations, is a critical regulator of vascular wall function in health and disease. A rapidly emerging concept is that the vascular adventitia acts as biological processing center for the retrieval, integration, storage, and release of key regulators of vessel wall function. In response to stress or injury, resident adventitial cells can be activated and reprogrammed to exhibit different functional and structural behaviors. In fact, under certain conditions, the adventitial compartment may be considered the principal injury-sensing tissue of the vessel wall. In response to vascular stresses such as overdistension and hypoxia, the adventitial fibroblast is activated and undergoes phenotypic changes, which include proliferation, differentiation, upregulation of contractile and extracellular matrix proteins, and release of factors that directly affect medial smooth muscle cell tone and growth and that stimulate recruitment of inflammatory and progenitor cells to the vessel wall. Each of these changes in fibroblast phenotype modulates either directly or indirectly changes in overall vascular function and structure. The purpose of this review is to present the current evidence demonstrating that the adventitial fibroblast acts as a key regulator of pulmonary vascular function and structure from the "outside-in."
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Affiliation(s)
- Kurt R Stenmark
- Division of Pediatric Critical Care, University of Colorado at Denver and Health Sciences Center, Denver, Colorado, USA.
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9
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Drexler ES, Quinn TP, Slifka AJ, McCowan CN, Bischoff JE, Wright JE, Ivy DD, Shandas R. Comparison of mechanical behavior among the extrapulmonary arteries from rats. J Biomech 2006; 40:812-9. [PMID: 16682044 DOI: 10.1016/j.jbiomech.2006.03.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2004] [Accepted: 03/13/2006] [Indexed: 11/18/2022]
Abstract
Results of comparative tests on pulmonary arteries from untreated Long-Evans rats are presented from three sections of the artery: the trunk, and the right and left main extrapulmonary arteries. Analyses were conducted looking for mechanical differences between the flow (longitudinal) and circumferential directions, between the right and left main arteries, and between each of the mains and the trunk. The mechanical properties of rat pulmonary arteries were obtained with a bubble inflation technique. A flat disk of rat pulmonary artery was constrained at the periphery and inflated, and the geometry of the resulting bubble of material recorded from six different angles. To analyze the data, the area under the stress-strain curve was calculated for each test and orientation. This area, related to the strain-energy density, was calculated at stress equal to 200kPa, for the purpose of statistical comparison. The mean values for the area show that the trunk is less compliant than the main arteries; this difference is supported by histological evidence. When comparing the circumferential and longitudinal properties of the arteries, differences are found for the trunk and left main arteries, but with opposite orientations being more compliant. The mean values for the two orientations for the right main artery are statistically identical. There was indication of significant difference in mechanical properties between the trunk and the main arteries. The left main artery in the circumferential orientation is highly compliant and appears to strongly influence the likelihood that significant differences will exist when included in a statistical population. These data show that each section of the extrapulmonary arterial system should not be expected to behave identically, and they provide the baseline mechanical behavior of the pulmonary artery from normotensive rats.
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Affiliation(s)
- E S Drexler
- Materials Reliability Division (MS 853), National Institute of Standards and Technology, 325 Broadway, Boulder, CO 80305, USA.
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10
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Guo X, Lu X, Ren H, Levin ER, Kassab GS. Estrogen modulates the mechanical homeostasis of mouse arterial vessels through nitric oxide. Am J Physiol Heart Circ Physiol 2005; 290:H1788-97. [PMID: 16306215 DOI: 10.1152/ajpheart.01070.2005] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We have recently shown that estrogen causes vessel dilation through receptor-mediated stimulation of nitric oxide (NO) production. Here, we hypothesize that estrogen modulates the mechanical homeostasis in the blood vessel wall through NO production. The mechanical properties of female ovariectomized (ovx) mice, female mice lacking the gene for endothelial NO synthase (eNOS(-/-)), and control female and male mice were studied to test the hypothesis. The femoral and carotid arteries and aorta were cannulated in situ and mechanically distended. The stress, strain, elastic modulus, and wall thickness of vessels in ovx and eNOS(-/-) mice, as well as intact female and male mice, were determined. Western blot and immunohistochemistry were used to assess eNOS protein expression in the aorta. Moreover, NO by-products of the femoral and carotid artery were determined by measuring the levels of nitrite and nitrate. Our results show that ovariectomy and eNOS(-/-) significantly decrease the strain in all arteries. Furthermore, the eNOS protein was significantly reduced in ovx mice. Finally, the NO metabolites were significantly decreased both in ovx and eNOS(-/-) mice. We found statistically significant correlations between the structural (wall thickness), mechanical (stress, strain, and elastic modulus), and biochemical parameters (NO by-products). These novel results connect NO to the structural and mechanical properties of the vessel wall. Hence, the effect of endogenous estrogen on the arterial mechanical properties is mediated by the regulation of NO derived from eNOS.
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Affiliation(s)
- Xiaomei Guo
- Department of Biomedical Engineering, University of California, Irvine, CA 92697-2715, USA
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11
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Schultze AE, Roth RA. Chronic pulmonary hypertension--the monocrotaline model and involvement of the hemostatic system. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART B, CRITICAL REVIEWS 1998; 1:271-346. [PMID: 9776954 DOI: 10.1080/10937409809524557] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Monocrotaline (MCT) is a toxic pyrrolizidine alkaloid of plant origin. Administration of small doses of MCT or its active metabolite, monocrotaline pyrrole (MCTP), to rats causes delayed and progressive lung injury characterized by pulmonary vascular remodeling, pulmonary hypertension, and compensatory right heart hypertrophy. The lesions induced by MCT(P) administration in rats are similar to those observed in certain chronic pulmonary vascular diseases of people. This review begins with a synopsis of the hemostatic system, emphasizing the role of endothelium since endothelial cell dysfunction likely underlies the pathogenesis of MCT(P)-induced pneumotoxicity. MCT toxicology is discussed, focusing on morphologic, pulmonary mechanical, hemodynamic, and biochemical and molecular alterations that occur after toxicant exposure. Fibrin and platelet thrombosis of the pulmonary microvasculature occurs after administration of MCT(P) to rats, and several investigators have hypothesized that thrombi contribute to the lung injury and pulmonary hypertension. The evidence for involvement of the various components of the hemostatic system in MCT(P)-induced vascular injury and remodeling is reviewed. Current evidence is consistent with involvement of platelets and an altered fibrinolytic system, yet much remains to be learned about specific events and signals in the vascular pathogenesis.
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MESH Headings
- Animals
- Disease Models, Animal
- Endothelium, Vascular/drug effects
- Endothelium, Vascular/pathology
- Hemostasis/drug effects
- Humans
- Hypertension, Pulmonary/blood
- Hypertension, Pulmonary/chemically induced
- Hypertension, Pulmonary/etiology
- Hypertrophy, Right Ventricular/blood
- Hypertrophy, Right Ventricular/chemically induced
- Hypertrophy, Right Ventricular/etiology
- Monocrotaline/adverse effects
- Monocrotaline/analogs & derivatives
- Monocrotaline/toxicity
- Plants, Medicinal/adverse effects
- Plants, Toxic/adverse effects
- Rats
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Affiliation(s)
- A E Schultze
- Department of Pathology, College of Veterinary Medicine, University of Tennessee, Knoxville, USA
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12
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Davidge ST, Gandley RE, McLaughlin MK. Altered active but not passive properties of mesenteric resistance arteries from the vitamin E-deprived rat. Br J Pharmacol 1998; 123:275-80. [PMID: 9489616 PMCID: PMC1565169 DOI: 10.1038/sj.bjp.0701639] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
1 We tested the hypothesis that lowering antioxidant protection through dietary vitamin E deprivation would alter active and passive mechanical properties in resistance arteries of the rat. Specifically, we hypothesized that vascular tone in isolated mesenteric arteries of the vitamin E-deprived rats would be altered due to impaired endothelial influences of nitric oxide and/or prostaglandins. 2 Lumen diameter and wall thickness were measured in pressurized arteries (approximately 250 microm diameter) from control (n=9) and vitamin E deprived (n=9) Sprague-Dawley female rats by use of a dimension analysing system. 3 Treatment with a cyclo-oxygenase inhibitor (meclofenamate) did not affect the basal vascular tone in either group. Treatment with a nitric oxide synthase inhibitor (NG-methyl-L-arginine) caused a significant increase in basal tone only in the vitamin E-deprived rats (% tone: 6.2+/-1.1 vs 1.2+/-0.3%; P<0.05). When tone was induced to 25% of the initial diameter with phenylephrine, treatment with the nitric oxide synthase inhibitor resulted in a greater potentiated tone in the vitamin E-deprived rats compared to the controls (26.5+/-2.7 vs 16.4+/-3.4%; P<0.05); suggesting a greater nitric oxide affect in the vessels from the vitamin E-deprived rats. Meclofenamate treatment in the induced tone arteries significantly relaxed (-17.4+/-4.0%; P<0.05) only the arteries from the vitamin E-deprived rats, indicating that a vasoconstrictor was modifying tone. The passive characteristics of distensibility and stress-strain relationship were not different between the two groups of rats. 4 In summary, vitamin E deprivation in the rat enhanced the modulation of vascular tone by both the nitric oxide and cyclo-oxygenase pathways but did not alter passive characteristics of mesenteric arteries.
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Affiliation(s)
- S T Davidge
- Perinatal Research Centre, University of Alberta, Edmonton, Canada
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13
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Arcot SS, Lipke DW, Gillespie MN, Olson JW. Alterations of growth factor transcripts in rat lungs during development of monocrotaline-induced pulmonary hypertension. Biochem Pharmacol 1993; 46:1086-91. [PMID: 8216353 DOI: 10.1016/0006-2952(93)90675-m] [Citation(s) in RCA: 77] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Although pathologic and hemodynamic changes in monocrotaline (MCT)-induced pulmonary hypertension have been studied extensively, relatively little is known about the inter- and intracellular signaling mechanisms underlying such alterations. As a first step to delineating signaling mechanisms governing adverse structural alterations in the hypertensive lungs, we examined changes in the steady-state levels of mRNAs encoding several growth factors including transforming growth factors (TGF), platelet-derived growth factors (PDGF), vascular endothelial cell growth factor (VEGF) and endothelin (ET) as a function of time in MCT-induced pulmonary hypertension in rats. These studies demonstrated a very diverse pattern of growth factor gene expression in response to MCT administration. In general, alterations in the steady-state levels of mRNAs encoding the growth factors preceded the onset of MCT-induced pulmonary hypertension. TGF-beta 1, -beta 2 and -beta 3 transcripts were seen to be elevated, whereas that of TGF-alpha and PDGF-A remained unchanged. Transcripts for PDGF-B and ET were increased in the early stages but declined to less than controls in the latter stages of MCT-induced hypertension. In contrast, levels of VEGF mRNA decreased to less than controls as the disease progressed. Viewed collectively, the diverse pattern of expression suggests that alterations in the levels of the growth factor transcripts may have a significant role in the development of pulmonary hypertensive disease and may be relevant to the pathological and structural changes in MCT-induced pulmonary hypertension.
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Affiliation(s)
- S S Arcot
- University of Kentucky A.B. Chandler Medical Center, College of Pharmacy, Division of Pharmacology and Experimental Therapeutics, Lexington 40536-0082
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14
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Belik J, Halayko AJ, Rao K, Stephens NL. Fetal ductus arteriosus ligation. Pulmonary vascular smooth muscle biochemical and mechanical changes. Circ Res 1993; 72:588-96. [PMID: 8431986 DOI: 10.1161/01.res.72.3.588] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
To evaluate the smooth muscle mechanical and biochemical changes associated with persistent pulmonary hypertension syndrome of the newborn, we studied 31 fetal sheep in which the ductus arteriosus was ligated at 125 days of gestation. Sixty-one noninstrumented and six sham-operated fetuses served as controls. All animals were delivered by cesarean section at 137-140 days of gestation, and the experimental group had the ductus arteriosus ligated for 12 +/- 3 days. The ligated group demonstrated a higher mean (+/- SEM) pulmonary artery pressure (72.3 +/- 3.8 versus 54.1 +/- 2 mm Hg, p < 0.01) and right ventricular mean free wall weight (12.5 +/- 0.7 versus 6.8 +/- 0.3 g, p < 0.01) as compared with the sham-operated group. Significant changes in the pulmonary vascular smooth muscle of the ligated group were observed. The myosin content of vessels from the second through fifth generation demonstrated a significant increase in actin and myosin content (p < 0.01), but given their disproportional changes, the noninstrumented group demonstrated a lower actin/myosin ratio than the experimental group (p < 0.01). Changes in the myosin heavy chain isoform stoichiometry, characterized by an increase in both the mean high/low myosin heavy chain isoform ratio (1.8 +/- 0.3 versus 1.0 +/- 0.1, p < 0.05) and the nonmuscle isoform as a percentage of the total myosin heavy chain (12.4 +/- 0.7% versus 2.7 +/- 0.9%, p < 0.01), were also observed in the ligated as compared with the noninstrumented animals. In addition, the muscle Mg-ATPase activity was significantly (p < 0.05) reduced in the experimental group.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- J Belik
- Department of Pediatrics, University of Manitoba, Winnipeg, Canada
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Wanstall JC, O'Donnell SR. Responses to vasodilator drugs on pulmonary artery preparations from pulmonary hypertensive rats. Br J Pharmacol 1992; 105:152-8. [PMID: 1596677 PMCID: PMC1908596 DOI: 10.1111/j.1476-5381.1992.tb14227.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
1. Relaxant responses to six vasodilator drugs, with different mechanisms of action, were examined on noradrenaline (0.1 microM)-contracted ring preparations of pulmonary artery and aorta taken from rats with pulmonary hypertension induced by monocrotaline or chronic hypoxia. 2. On pulmonary artery preparations from monocrotaline-treated rats, compared with controls, (a) the maximum relaxation to pinacidil and cromakalim was significantly increased, but their potency (negative log EC50) was unchanged, (b) the potencies of nitroprusside and sodium nitrite were significantly reduced (10 fold and 3 fold respectively), but there was no change in the maxima, (c) for nicorandil there was an increase in maximum relaxation and a decrease in potency (3 fold), and (d) for atriopeptin II there was no change in potency or maximum. 3. The increase in maximum relaxation for pinacidil and the decrease in potency for nitroprusside were also demonstrated in pulmonary artery preparations from rats with chronic hypoxic pulmonary hypertension. The other four drugs were not examined in preparations from hypoxic rats. 4. In both models of pulmonary hypertension, no change in maximum response or potency was seen on aortic preparations for any of the vasodilator drugs. 5. In control preparations, none of the drugs was more potent on pulmonary artery than on aorta (i.e. they were not pulmonary-selective). In preparations from pulmonary hypertensive rats, pinacidil was selective for pulmonary artery, in contrast to nitroprusside which was selective for aorta.6. It is concluded that the development of pulmonary hypertension in rats is accompanied by changes in the responsiveness of the pulmonary arteries to some vasodilator drugs; whether or not these changes occur depends on the mechanism of action of the vasodilator drug, but they are independent of the method of inducing pulmonary hypertension.7. It is postulated that the reduction in potency seen for nitroprusside, sodium nitrite and nicorandil may be due to desensitization of soluble guanylate cyclase in pulmonary vascular smooth muscle in pulmonary hypertension.
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Affiliation(s)
- J C Wanstall
- Department of Physiology and Pharmacology, University of Queensland, Australia
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Wanstall JC, O'Donnell SR. Endothelin and 5-hydroxytryptamine on rat pulmonary artery in pulmonary hypertension. Eur J Pharmacol 1990; 176:159-68. [PMID: 2107090 DOI: 10.1016/0014-2999(90)90524-a] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Contractile responses to endothelin, 5-hydroxytryptamine (5-HT), noradrenaline and potassium were obtained on isolated preparations of pulmonary artery from rats made pulmonary hypertensive by an injection of monocrotaline (105 mg/kg s.c.) 4 weeks previously. When compared with data obtained in control rats, the potencies (negative log EC50 values) for 5-HT, noradrenaline and potassium were increased (30, 3- and 3-fold, respectively), and the maximum contractions (mN/mm2) to endothelin, noradrenaline and potassium were reduced (65, 40 and 45% reduction). These changes were not seen 2 weeks after injection of monocrotaline, before pulmonary hypertension developed, or in preparations of aorta. It is concluded that monocrotaline-induced pulmonary hypertension affects pulmonary vascular responsiveness to spasmogens differentially. The comparative importance of endothelin and 5-HT as pulmonary vasoconstrictors may change in monocrotaline-induced pulmonary hypertension, there being an increase in responsiveness to 5-HT and a decrease in responsiveness to endothelin.
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Affiliation(s)
- J C Wanstall
- Department of Physiology and Pharmacology, Brisbane, Australia
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17
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Abstract
Pyrrolizidine alkaloids unsaturated in the 1,2 position are hepatotoxins. Certain of them, such as monocrotaline, are also pneumotoxins, producing pulmonary arterial hypertension and right ventricular hypertrophy as a delayed response two weeks after administration. Pneumotoxicity is the result of hepatic metabolism, the lung itself being unable to bioactivate pyrrolizidine alkaloids. The changes produced in the lung following exposure to pneumotoxic pyrrolizidine alkaloids are reviewed, together with the factors and interventions which modify or influence these changes. In the main, the earliest changes are seen in vascular smooth muscle and in the interactions between the smooth muscle and the endothelium. The search to identify the pneumotoxic metabolite is reviewed. It is generally accepted that pyrroles, or dehydroalkaloids, are responsible for the toxicity of pyrrolizidines. However, the primary pyrroles are intensely reactive, hydrolyzing and polymerizing within seconds in aqueous solution. Evidence for and against the pneumotoxin being a primary pyrrole or a stabilized secondary conversion product of a primary pyrrole is discussed.
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Affiliation(s)
- R J Huxtable
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson 85724
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