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Ibe BO, Portugal AM, Chaturvedi S, Raj JU. Oxygen-dependent PAF receptor binding and intracellular signaling in ovine fetal pulmonary vascular smooth muscle. Am J Physiol Lung Cell Mol Physiol 2004; 288:L879-86. [PMID: 15618453 DOI: 10.1152/ajplung.00341.2004] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Circulating levels of platelet-activating factor (PAF) are high in the fetus, and PAF is active in maintaining high PVR in fetal hypoxia (Ibe BO, Hibler S, Raj J. J Appl Physiol 85: 1079-1085, 1998). PAF synthesis by fetal pulmonary vascular smooth muscle cells (PVSMC) is high in hypoxia, but how oxygen tension affects PAF receptor (PAF-r) binding in PVSMC is not known. We studied the effect of oxygen tension on PAF-r binding and signaling in fetal PVSMC. PAF binding was saturable. PAF-r density (B(max): fmol/10(6) cells; means +/- SE, n = 6), 25.2 +/- 0.77 during hypoxia (Po(2) <40 Torr), was higher than 13.9 +/- 0.44 during normoxia (Po(2) approximately 100 Torr). K(d) was twofold lower in hypoxia than normoxia. PAF-r protein expression, 35-40% greater in hypoxia, was inhibited by cycloheximide, a protein synthesis inhibitor, suggesting translational regulation. IP(3) release, an index of PAF-r-mediated cell signaling, was greater in hypoxia (EC(50): hypoxia, 2.94 +/- 0.61; normoxia, 5.85 +/- 0.51 nM). Exogenous PAF induced 50-90% greater intracellular calcium flux in cells during hypoxia, indicating hypoxia augments PAF-r-mediated cell signaling. PAF-r phosphorylation, with or without 5 nM PAF, was 40% greater in hypoxia. These data show 1) hypoxia upregulates PAF-r binding, PAF-r phosphorylation, and PAF-r-mediated intracellular signaling, evidenced by augmented IP(3) production and intracellular Ca(2+) flux; and 2) hypoxia-induced PAF-r phosphorylation results in activation of PAF-r-mediated signal transduction. The data suggest the fetal hypoxic environment facilitates PAF-r binding and signaling, thereby promoting PAF-mediated pulmonary vasoconstriction and maintenance of high PVR in utero.
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Affiliation(s)
- Basil O Ibe
- Dept. of Pediatrics, University of California, Los Angeles, CA, USA.
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52
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Archer SL, Wu XC, Thébaud B, Nsair A, Bonnet S, Tyrrell B, McMurtry MS, Hashimoto K, Harry G, Michelakis ED. Preferential expression and function of voltage-gated, O2-sensitive K+ channels in resistance pulmonary arteries explains regional heterogeneity in hypoxic pulmonary vasoconstriction: ionic diversity in smooth muscle cells. Circ Res 2004; 95:308-18. [PMID: 15217912 DOI: 10.1161/01.res.0000137173.42723.fb] [Citation(s) in RCA: 141] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Hypoxic pulmonary vasoconstriction (HPV) is initiated by inhibition of O2-sensitive, voltage-gated (Kv) channels in pulmonary arterial smooth muscle cells (PASMCs). Kv inhibition depolarizes membrane potential (E(M)), thereby activating Ca2+ influx via voltage-gated Ca2+ channels. HPV is weak in extrapulmonary, conduit pulmonary arteries (PA) and strong in precapillary resistance arteries. We hypothesized that regional heterogeneity in HPV reflects a longitudinal gradient in the function/expression of PASMC O2-sensitive Kv channels. In adult male Sprague Dawley rats, constrictions to hypoxia, the Kv blocker 4-aminopyridine (4-AP), and correolide, a Kv1.x channel inhibitor, were endothelium-independent and greater in resistance versus conduit PAs. Moreover, HPV was dependent on Kv-inhibition, being completely inhibited by pretreatment with 4-AP. Kv1.2, 1.5, Kv2.1, Kv3.1b, Kv4.3, and Kv9.3. mRNA increased as arterial caliber decreased; however, only Kv1.5 protein expression was greater in resistance PAs. Resistance PASMCs had greater K+ current (I(K)) and a more hyperpolarized E(M) and were uniquely O2- and correolide-sensitive. The O2-sensitive current (active at -65 mV) was resistant to iberiotoxin, with minimal tityustoxin sensitivity. In resistance PASMCs, 4-AP and hypoxia inhibited I(K) 57% and 49%, respectively, versus 34% for correolide. Intracellular administration of anti-Kv1.5 antibodies inhibited correolide's effects. The hypoxia-sensitive, correolide-insensitive I(K) (15%) was conducted by Kv2.1. Anti-Kv1.5 and anti-Kv2.1 caused additive depolarization in resistance PASMCs (Kv1.5>Kv2.1) and inhibited hypoxic depolarization. Heterologously expressed human PASMC Kv1.5 generated an O2- and correolide-sensitive I(K) like that in resistance PASMCs. In conclusion, Kv1.5 and Kv2.1 account for virtually all the O2-sensitive current. HPV occurs in a Kv-enriched resistance zone because resistance PASMCs preferentially express O2-sensitive Kv-channels.
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MESH Headings
- 4-Aminopyridine/pharmacology
- Acetylcholine/pharmacology
- Animals
- Cell Hypoxia
- Cells, Cultured/drug effects
- Cells, Cultured/physiology
- Gene Expression Regulation
- Humans
- Hypoxia/physiopathology
- Ion Channel Gating/drug effects
- Ion Transport/drug effects
- Kv1.5 Potassium Channel
- Male
- Membrane Potentials/drug effects
- Muscle, Smooth, Vascular/pathology
- Myocytes, Smooth Muscle/drug effects
- Myocytes, Smooth Muscle/physiology
- Oxygen/pharmacology
- Patch-Clamp Techniques
- Peptides/pharmacology
- Potassium/metabolism
- Potassium Channels, Voltage-Gated/biosynthesis
- Potassium Channels, Voltage-Gated/genetics
- Potassium Channels, Voltage-Gated/physiology
- Pulmonary Artery/pathology
- Pulmonary Circulation/drug effects
- Pulmonary Circulation/physiology
- Rats
- Rats, Sprague-Dawley
- Recombinant Fusion Proteins/physiology
- Scorpion Venoms/pharmacology
- Shab Potassium Channels
- Transduction, Genetic
- Triterpenes/pharmacology
- Vascular Resistance/drug effects
- Vascular Resistance/physiology
- Vasoconstriction/drug effects
- Vasoconstriction/physiology
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Affiliation(s)
- Stephen L Archer
- Heart and Stroke Chair in Cardiovascular Research, Cardiology Division, Department of Medicine, University of Alberta, WMC 2C2.36, 8440 112th St, Edmonton, Alberta T6G 2B7, Canada.
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53
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Bailly K, Ridley AJ, Hall SM, Haworth SG. RhoA Activation by Hypoxia in Pulmonary Arterial Smooth Muscle Cells Is Age and Site Specific. Circ Res 2004; 94:1383-91. [PMID: 15087418 DOI: 10.1161/01.res.0000128405.83582.2e] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Hypoxia induces vasoconstriction of pulmonary arteries through contraction of smooth muscle cells (SMCs). The GTPase RhoA regulates smooth muscle contractility and actin cytoskeletal remodeling through the Rho-associated kinase (ROCK). We previously found that the postnatal fall in pulmonary vascular resistance was associated with actin cytoskeletal remodeling in porcine pulmonary arterial SMCs (PASMCs) in vivo. Here, we investigated the effects of acute and chronic hypoxia on the morphology and RhoA activity of PASMCs from fetal and neonatal piglets. Acute hypoxia enhanced actin stress fiber formation and RhoA activity in both inner and outer medial PASMCs from the fetus but only in the inner medial PASMCs from normal 3-day-old piglets. The increased stress fiber formation was dependent on Rho and ROCK. In outer medial PASMCs from 14-day-old animals, acute hypoxia decreased RhoA activity. Interestingly, outer medial PASMCs from animals exposed to chronic hypoxia had fewer stress fibers associated with a lower basal RhoA activity. Treatment of PASMCs from normal 3-day-old piglets with Rho or ROCK inhibitors for 24 hours induced a similar morphology. Rac activity was not altered by either acute or chronic hypoxia. These data show that acute hypoxia induces RhoA activation only in PASMCs from young animals, whereas chronic hypoxia selectively downregulates RhoA activity in outer medial PASMCs leading to an altered phenotype.
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Affiliation(s)
- Karine Bailly
- Vascular Biology and Pharmacology Unit, Institute of Child Health, University College London, UK
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54
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Stiebellehner L, Frid MG, Reeves JT, Low RB, Gnanasekharan M, Stenmark KR. Bovine distal pulmonary arterial media is composed of a uniform population of well-differentiated smooth muscle cells with low proliferative capabilities. Am J Physiol Lung Cell Mol Physiol 2003; 285:L819-28. [PMID: 12857671 DOI: 10.1152/ajplung.00062.2003] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The media of the normal bovine main pulmonary artery (MPA) is composed of phenotypically heterogeneous smooth muscle cells (SMC) with markedly different proliferative capabilities in response to serum, mitogens, and hypoxia. Little, however, is known of the SMC phenotype in distal pulmonary arteries (PA), particularly in arterioles, which regulate the pulmonary circulation. With a panel of muscle-specific antibodies against alpha-smooth muscle (SM)-actin, SM-myosin heavy chains (SM-MHC), SM-MHC-B isoform, desmin, and meta-vinculin, we demonstrate a progressive increase in phenotypic uniformity and level of differentiation of SMC along the proximal-to-distal axis of normal adult bovine pulmonary circulation so that the media of distal PA (1,500- to 100-microm diameter) is composed of a phenotypically uniform population of "well-differentiated" SMC. Similarly, when isolated and assessed in vitro, distal PA-SMC is composed of a single, uniform population of differentiated SMC that exhibited minimal growth responses to a variety of mitogens while their cell size increased substantially in response to serum. Their growth was inhibited by hypoxic exposure under all conditions tested. Distal PA-SMC also differed from MPA-SMC by exhibiting a distinct pattern of DNA synthesis in response to serum and mitogens. Thus, in contrast to the MPA, distal PA media is composed of an apparently uniform population of well-differentiated SMC that are proliferation resistant and have a substantial capacity to hypertrophy in response to growth-promoting stimuli. We thus speculate that distinct SMC phenotypes present in distal vs. proximal PA may confer different response mechanisms during remodeling in conditions such as hypertension.
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Affiliation(s)
- Leopold Stiebellehner
- Developmental Lung Biology Research, Univ. of Colorado Health Sciences Center, 4200 E. 9th Ave., Box B131, Denver, CO 80262, USA
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55
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Yamasaki M, Kawai J, Nakaoka T, Ogita T, Tojo A, Fujita T. Adrenomedullin overexpression to inhibit cuff-induced arterial intimal formation. Hypertension 2003; 41:302-7. [PMID: 12574099 DOI: 10.1161/01.hyp.0000050645.11117.9e] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Adrenomedullin (AM) inhibits vascular smooth muscle cell proliferation stimulated by fetal calf serum and platelet-derived growth factor in vitro. In this study, an adenovirus expressing AM (AxCAAM) was created to examine the in vivo action of AM. Femoral arteries of Wistar rats were wrapped with a silicone cuff and treated with adenovirus expressing Escherichia coli beta-galactosidase (AxCALacZ) or AxCAAM. Immunoreactivity for endothelial nitric oxide synthase (eNOS) was reduced in the endothelium of cuff-injured arteries and was associated with increased local DNA synthesis. Consequently, the intimal formation measured by the intimal-to-medial ratio was significantly increased at 14 and 28 days after the cuff placement. AxCAAM-infected arteries increased the expression of eNOS in the endothelium and inducible NOS in the media and the adventitia. AxCAAM significantly decreased the intimal-to-medial ratio by 40% at 14 days and 51% at 28 days, whereas AxCALacZ showed no changes compared with cuff-injured control arteries. AM overexpression effectively limits intimal hyperplasia by reducing cell proliferation through a nitric oxide-dependent pathway of eNOS. Our findings suggest the possibility of a therapeutic use of the AM gene for the prevention of vascular proliferative disorders.
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Affiliation(s)
- Masao Yamasaki
- Department of Internal Medicine, Faculty of Medicine, University of Tokyo, Tokyo, Japan
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56
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Parker TA, Abman SH. The pulmonary circulation in bronchopulmonary dysplasia. SEMINARS IN NEONATOLOGY : SN 2003; 8:51-61. [PMID: 12667830 DOI: 10.1016/s1084-2756(02)00191-4] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Abnormalities of the pulmonary circulation are increasingly being recognized as a major contributor to the high morbidity and mortality of bronchopulmonary dysplasia. Historically, studies have focused on the importance of pulmonary hypertension to the pathophysiology of BPD, with the assumption that pulmonary vascular abnormalities are a secondary consequence of primary injury to the airspace. Recent studies suggest, however, that abnormalities of the pulmonary vasculature, including altered growth and structure, may directly contribute to the abnormal alveolarization that characterizes the condition. In this article, we briefly outline mechanisms of pulmonary vascular injury in infants at risk of BPD. We then focus on the recognition and management of pulmonary hypertension in these infants. Finally, we review how disordered pulmonary vascular growth may contribute to the pathogenesis of BPD and emphasize the importance of the reciprocal development of the airspace and the pulmonary circulation.
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Affiliation(s)
- Thomas A Parker
- Pediatric Heart Lung Center, University of Colorado School of Medicine, 80206, Denver, CO, USA.
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57
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Lin SJ, Yang TH, Chen YH, Chen JW, Kwok CF, Shiao MS, Chen YL. Effects of Ginkgo biloba extract on the proliferation of vascular smooth muscle cells in vitro and on intimal thickening and interleukin-1beta expression after balloon injury in cholesterol-fed rabbits in vivo. J Cell Biochem 2002; 85:572-82. [PMID: 11967997 DOI: 10.1002/jcb.10151] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Restenosis may develop in response to cytokine activation and smooth muscle cell proliferation. Ginkgo biloba extract (EGb) has been used to treat cardiovascular and cerebrovascular diseases. In the present study, the effects of EGb on the growth of cultured vascular smooth muscle cells (VSMC), as well as on the expression of interleukin-1beta (IL-1beta) and the intimal response in balloon-injured arteries of cholesterol-fed rabbits, were investigated. Using bromodeoxyuridine incorporation as an index of cell proliferation, EGb was found to inhibit serum-induced mitogenesis of cultured rat aorta VSMC in a dose-dependent manner. In vivo, EGb and probucol ( positive control) reduced the atheroma area in thoracic aortas of male New Zealand white rabbits fed a 2% cholesterol diet for 6 weeks with balloon denudation of the abdominal aorta being performed at the end of the third week. Intimal hyperplasia, expressed as the intimal/medial area ratio, in the abdominal aortas was significantly inhibited in the both the EGb group (0.61 +/- 0.06) and the probucol group (0.55 +/- 0.03) compared to the C group (0.87 +/- 0.02). In the balloon-injured abdominal aorta, both EGb and probucol significantly reduced IL-1beta mRNA and protein expression and the percentage of proliferating cells. The inhibitory effects of EGb on the intimal response might be attributed to its antioxidant capacity. EGb may have therapeutic potential for the prevention of restenosis after angioplasty.
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MESH Headings
- Angioplasty, Balloon/adverse effects
- Animals
- Anticholesteremic Agents/pharmacology
- Aorta, Abdominal/drug effects
- Aorta, Abdominal/injuries
- Aorta, Abdominal/pathology
- Aorta, Thoracic/drug effects
- Aorta, Thoracic/pathology
- Arteriosclerosis/drug therapy
- Arteriosclerosis/pathology
- Cell Division/drug effects
- Cells, Cultured
- Cholesterol/pharmacology
- Copper/pharmacology
- Disease Models, Animal
- Ginkgo biloba
- Interleukin-1/genetics
- Interleukin-1/metabolism
- Lipoproteins, LDL/drug effects
- Lipoproteins, LDL/metabolism
- Male
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Plant Extracts/pharmacology
- Probucol/pharmacology
- Rabbits
- Rats
- Rats, Sprague-Dawley
- Tunica Intima/drug effects
- Tunica Intima/injuries
- Tunica Intima/pathology
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Affiliation(s)
- Shing-Jong Lin
- Institute of Clinical Medicine, National Yang-Ming University, Taipei, Taiwan
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58
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Lau HKF, Ho J. Regulation of plasminogen activator inhibitor-1 secretion by growth factors in smooth muscle cells. Blood Coagul Fibrinolysis 2002; 13:541-9. [PMID: 12192306 DOI: 10.1097/00001721-200209000-00009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Epithelioid-type vascular smooth muscle cells are metabolically active and secrete many proteases and protease inhibitors. We have previously cloned epithelioid-type smooth muscle cells from rat carotid arteries, and showed that polypeptide growth factors basic fibroblast growth factor (bFGF) and platelet-derived growth factor (PDGF) could dose-dependently induce plasminogen activator inhibitor-1 (PAI-1) secretion from these cells. In the present study, we have used these cells to investigate the growth factor-induced signal transduction pathways leading to PAI-1 secretion. We report here that PAI-1 induction was dependent on protein kinase C (PKC) and tyrosine kinase but not on protein kinase A (PKA), ras and phosphoinositol-3-kinase inhibitor. Induction of PAI-1 by bFGF and PDGF was also accompanied by activation of a mitogen-activated protein kinase pathway involving Raf/Mek/Erk1/2, and the family non-receptor tyrosine kinases., another non-receptor tyrosine kinase, on the contrary, behaved differently from in that it was part of a pathway leading to PAI-1 induction by bFGF, but not when PDGF was used as the stimulating reagent. Activation of a PKA-dependent pathway(s) opposed PAI-1 induction. One mechanism for PKA activators to inhibit PAI-1 secretion was that they markedly inhibited the phosphorylations of Mek and mitogen-activated protein kinase that were up-regulated in the presence of bFGF and PDGF.
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Affiliation(s)
- H K F Lau
- Division of Hematology, Department of Medicine, St Michael's and University of Toronto, Ontario, Canada.
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59
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Zacour ME, Teoh H, Halayko AJ, Ward ME. Mechanisms of aortic smooth muscle hyporeactivity after prolonged hypoxia in rats. J Appl Physiol (1985) 2002; 92:2625-32. [PMID: 12015382 DOI: 10.1152/japplphysiol.00818.2001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The aim of this study was to determine whether the effects of hypoxia on aortic contractility reflect a decrease in smooth muscle activation [phosphorylation of the 20-kDa myosin regulatory light chain (LC(20))], the capacity for myofibrillar ATP hydrolysis (mATPase activity), or both. Our results indicate that, in endothelium-denuded aortic rings from rats exposed to hypoxia for 48 h (inspired O(2) concentration = 10%), contractions to phenylephrine and potassium chloride (KCl) are impaired compared with rings from normoxic rats. The proportion of phosphorylated to total LC(20) during aortic contraction induced by 10(-5) M phenylephrine was reduced after hypoxia (51.4 +/- 5.4% in normoxic control rats vs. 32.5 +/- 4.7% in hypoxic rats, P < 0.01). Aortic mATPase activity was also decreased (maximum ATPase rate = 29.6 +/- 3.4 and 20.7 +/- 3.7 nmol. min(-1). mg protein(-1) in control and hypoxic rats, respectively, P < 0.05). Neither proliferation nor dedifferentiation of aortic smooth muscle was evident in this model; immunostaining for smooth muscle expression of the proliferating cell nuclear antigen was negative and smooth muscle-specific isoforms of myosin heavy chains, h-caldesmon, and calponin were increased, not decreased, after hypoxic exposure. Decreased aortic reactivity after hypoxia is associated with both impairment of smooth muscle activation and diminished capacity of the actomyosin complex, once activated, to hydrolyze ATP. These changes cannot be attributed to smooth muscle dedifferentiation or to reduced contractile protein expression.
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Affiliation(s)
- Mary E Zacour
- Meakins-Christie Laboratories, McGill University, Montreal H3A 2T5, Canada R3T 2N2
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60
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Boulom V, Lee HW, Zhao L, Eghbali-Webb M. Stimulation of DNA synthesis, activation of mitogen-activated protein kinase ERK2 and nuclear accumulation of c-fos in human aortic smooth muscle cells by ketamine. Cell Prolif 2002; 35:155-65. [PMID: 12027951 PMCID: PMC6495842 DOI: 10.1046/j.1365-2184.2002.00233.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Proliferation of vascular smooth muscle cells is known to be regulated by autocrine and paracrine stimuli, including extracellular matrix, reactive oxygen species, lipids, and biomechanical forces. The effect of many pharmacological agents to which smooth muscle cells may be exposed, however, is widely unexplored. Ketamine, an intravenous anaesthetic and a phencyclidine derivative, regulates diverse intracellular signalling pathways in smooth muscle cells, several of which are known to affect cell proliferation. The effect of ketamine on proliferative response of smooth muscle cells, however, is not determined. We tested the hypothesis that ketamine may regulate proliferation of smooth muscle cells, and investigated the effects of pharmacological doses of ketamine on their proliferative capacity by measuring DNA synthesis and activation of mitogen-activated protein (MAP) kinase signalling pathway in human aortic smooth muscle cells. DNA synthesis, as determined by incorporation of 3H-thymidine into DNA, was enhanced by 73% (P < 0.0001) and 130% (P < 0.0001) with 10 and 100 microm ketamine, respectively. Ketamine-induced DNA synthesis was dependent on de novo protein synthesis, as it was abolished by an inhibitor of protein synthesis, cycloheximide. A synthetic inhibitor of MAP kinase pathway, PD98059, decreased 50% (P < 0.0001) of ketamine-induced DNA synthesis, suggesting that the activation of MAP kinase pathway was partially responsible for ketamine-induced effects. Consistently, in-gel kinase assay and in vitro kinase assay of cell lysates showed ketamine-induced MAP kinase activation and expression of ERK2 (extracellular signal-regulated kinase) in smooth muscle cells. This effect of ketamine was not dependent on de novo protein synthesis. Immunofluorescent light microscopy showed ketamine-induced nuclear accumulation of c-fos, a downstream effect of MAP kinase activation, in smooth muscle cells. In conclusion, these data support the hypothesis of the study and demonstrate that ketamine, by stimulating DNA synthesis in human aortic smooth muscle cells, may have an impact on proliferative capacity of these cells. The present results also demonstrate that ketamine induces the activation of MAP kinase pathway and nuclear accumulation of transcription factor c-fos in smooth muscle cells. They further demonstrate that the activation of MAP kinases is partially responsible for ketamine-induced DNA synthesis in human aortic smooth muscle cells. Together, these findings suggest that ketamine may play a role as a pharmacological regulator of mechanisms involved in proliferation of smooth muscle cells.
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Affiliation(s)
- V Boulom
- Department of Anaesthesiology, Yale University School of Medicine, New Haven, CT 06510, USA
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61
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Jeffery TK, Wanstall JC. Pulmonary vascular remodeling: a target for therapeutic intervention in pulmonary hypertension. Pharmacol Ther 2001; 92:1-20. [PMID: 11750034 DOI: 10.1016/s0163-7258(01)00157-7] [Citation(s) in RCA: 208] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Pulmonary vascular remodelling is an important pathological feature of pulmonary hypertension, leading to increased pulmonary vascular resistance and reduced compliance. It involves thickening of all three layers of the blood vessel wall (due to hypertrophy and/or hyperplasia of the predominant cell type within each layer), as well as extracellular matrix deposition. Neomuscularisation of non-muscular arteries and formation of plexiform and neointimal lesions also occur. Stimuli responsible for remodelling involve transmural pressure, stretch, shear stress, hypoxia, various mediators [angiotensin II, endothelin (ET)-1, 5-hydroxytryptamine, growth factors, and inflammatory cytokines], increased serine elastase activity, and tenascin-C. In addition, there are reductions in the endothelium-derived antimitogenic substances, nitric oxide, and prostacyclin. Intracellular signalling mechanisms involved in pulmonary vascular remodelling include elevations in intracellular Ca2+ and activation of the phosphatidylinositol pathway, protein kinase C, and mitogen-activated protein kinase. In animal models of pulmonary hypertension, various drugs have been shown to attenuate pulmonary vascular remodelling. These include angiotensin-converting enzyme inhibitors, angiotensin receptor antagonists, ET receptor antagonists, ET-converting enzyme inhibitors, nitric oxide, phosphodiesterase 5 inhibitors, prostacyclin, Ca2+ -channel antagonists, heparin, and serine elastase inhibitors. Inhibition of remodelling is generally accompanied by reductions in pulmonary artery pressure. The efficacy of some of the drugs varies, depending on the animal model of the disease. In view of the complexity of the remodelling process and the diverse aetiology of pulmonary hypertension in humans, it is to be anticipated that successful anti-remodelling therapy in the clinic will require a range of different drug options.
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MESH Headings
- Animals
- Endothelium, Vascular/physiology
- Humans
- Hypertension, Pulmonary/drug therapy
- Hypertension, Pulmonary/metabolism
- Hypertension, Pulmonary/pathology
- Hypertrophy/drug therapy
- Hypertrophy/pathology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Muscle, Smooth, Vascular/pathology
- Pulmonary Artery/drug effects
- Pulmonary Artery/metabolism
- Pulmonary Artery/pathology
- Pulmonary Veins/drug effects
- Pulmonary Veins/metabolism
- Pulmonary Veins/pathology
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Affiliation(s)
- T K Jeffery
- Department of PhysiologyPharmacology, The University of Queensland, St Lucia, Brisbane, Queensland, 4072, Australia
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62
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Li S, Fan YS, Chow LH, Van Den Diepstraten C, van Der Veer E, Sims SM, Pickering JG. Innate diversity of adult human arterial smooth muscle cells: cloning of distinct subtypes from the internal thoracic artery. Circ Res 2001; 89:517-25. [PMID: 11557739 DOI: 10.1161/hh1801.097165] [Citation(s) in RCA: 100] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Vascular smooth muscle cells (SMCs) perform diverse functions and this functional heterogeneity could be based on differential recruitment of distinct SMC subsets. In humans, however, there is little support for such a paradigm, partly because isolation of pure human SMC subsets has proven difficult. We report the cloning of 12 SMC lines from a single fragment of human internal thoracic artery and the elucidation of 2 distinct cellular profiles. Epithelioid clones (n=9) were polygonal at confluence, 105+/-9 micrometer in length, and had a doubling time of 39+/-2 hours. Spindle-shaped clones (n=3) were larger (267+/-18 micrometer long, P<0.01) and grew slower (doubling time 65+/-4 hours, P<0.01). Both types of clones expressed smooth muscle (SM) alpha-actin, SM-myosin heavy chains, h-caldesmon, and calponin, but only spindle-shaped clones expressed metavinculin. Epithelioid clones displayed greater proliferation in response to platelet-derived growth factor-BB and fibroblast growth factor-2 and were more responsive to the migratory effect of platelet-derived growth factor-BB. Spindle-shaped clones showed more robust Ca(2+) transients in response to angiotensin II, histamine, and norepinephrine, crawled more quickly, and expressed more type I collagen. On serum withdrawal, spindle-shaped clones differentiated into a contraction-competent cell. A regional basis for diversity among SMCs was suggested by stepwise arterial digestion, which liberated small, SM alpha-actin-positive cells from the abluminal medial layers and larger SMCs from all layers. These results identify inherent SMC diversity in the media of the adult internal thoracic artery and suggest differential participation of SMC subsets in the regulation of human arterial behavior.
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Affiliation(s)
- S Li
- John P. Robarts Research Institute, London Health Science Centre, Department of Pathology, University of Western Ontario, London, Canada
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63
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Michelakis ED, Weir EK. The pathobiology of pulmonary hypertension. Smooth muscle cells and ion channels. Clin Chest Med 2001; 22:419-32. [PMID: 11590838 DOI: 10.1016/s0272-5231(05)70281-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Chronic hypoxic pulmonary arterial hypertension, APAH, and PPAH are characterized by vasoconstriction and vascular remodeling and are associated with decreased Kv currents in PA smooth muscle cells. Although Kv2.1 is less well studied, it seems that Kv1.5 is particularly important in the pulmonary circulation in animals and humans because it has been implicated in physiologic phenomena (HPV) and all of the aforementioned pulmonary hypertensive disorders. This occurrence is perhaps because of the fact that it controls Em in the PA smooth muscle cells and it has a short turnover half time. It is also certain that the pathogenesis of PPAH is multifactorial and not a result of a single abnormality. The recently discovered "PPAH gene" in chromosome 2q in patients with familial PPAH (6%-12% of patients) does not seem to encode for any Kv channels. Kv1.5 abnormalities, however, are likely to be a strong predisposing factor that, in association with others such as endothelial dysfunction, [figure: see text] anorexigen use, or viral infections, will initiate a process that eventually leads to PPAH. The selective Kv1.5 down-regulation leaves wide open the door to replacement gene therapy in pulmonary hypertension research.
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Affiliation(s)
- E D Michelakis
- Department of Medicine, Division of Cardiology, the Vascular Biology Group, University of Alberta, Edmonton, Canada.
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64
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Sodhi CP, Phadke SA, Batlle D, Sahai A. Hypoxia stimulates osteopontin expression and proliferation of cultured vascular smooth muscle cells: potentiation by high glucose. Diabetes 2001; 50:1482-90. [PMID: 11375351 DOI: 10.2337/diabetes.50.6.1482] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
We examined the effect of hypoxia on proliferation and osteopontin (OPN) expression in cultured rat aortic vascular smooth muscle (VSM) cells. In addition, we determined whether hypoxia-induced increases in OPN and cell proliferation are altered under hyperglycemic conditions. Quiescent cultures of VSM cells were exposed to hypoxia (3% O(2)) or normoxia (18% O(2)) in a serum-free medium, and cell proliferation as well as the expression of OPN was assessed. Cells exposed to hypoxia for 24 h exhibited a significant increase in [(3)H]thymidine incorporation followed by a significant increase in cell number at 48 h in comparison with respective normoxic controls. Exposure to hypoxia produced significant increases in OPN protein and mRNA expression at 2 h followed by a gradual decline at 6 and 12 h, with subsequent significant increases at 24 h. Neutralizing antibodies to either OPN or its receptor beta3 integrin but not neutralizing antibodies to beta5 integrin prevented the hypoxia-induced increase in [(3)H]thymidine incorporation. Inhibitors of protein kinase C (PKC) and p38 mitogen-activated protein (MAP) kinase also reduced the hypoxia-induced stimulation of proliferation and OPN synthesis. Exposure to high-glucose (HG) (25 mmol/l) medium under normoxic conditions also resulted in significant increases in OPN protein and mRNA levels as well as the proliferation of VSM cells. Under hypoxic conditions, HG further stimulated OPN synthesis and cell proliferation in an additive fashion. In conclusion, hypoxia-induced proliferation of cultured VSM cells is mediated by the stimulation of OPN synthesis involving PKC and p38 MAP kinase. In addition, hypoxia also enhances the effect of HG conditions on both OPN and proliferation of cultured VSM cells, which may have important implications in the development of diabetic atherosclerosis associated with arterial wall hypoxia.
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Affiliation(s)
- C P Sodhi
- Division of Nephrology and Hypertension, Northwestern University Medical School, 303 E. Chicago Ave., Chicago, IL 60611, USA
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65
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Platoshyn O, Yu Y, Golovina VA, McDaniel SS, Krick S, Li L, Wang JY, Rubin LJ, Yuan JX. Chronic hypoxia decreases K(V) channel expression and function in pulmonary artery myocytes. Am J Physiol Lung Cell Mol Physiol 2001; 280:L801-12. [PMID: 11238022 DOI: 10.1152/ajplung.2001.280.4.l801] [Citation(s) in RCA: 124] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Activity of voltage-gated K+ (KV) channels regulates membrane potential (E(m)) and cytosolic free Ca2+ concentration ([Ca2+](cyt)). A rise in ([Ca2+](cyt))in pulmonary artery (PA) smooth muscle cells (SMCs) triggers pulmonary vasoconstriction and stimulates PASMC proliferation. Chronic hypoxia (PO(2) 30-35 mmHg for 60-72 h) decreased mRNA expression of KV channel alpha-subunits (Kv1.1, Kv1.5, Kv2.1, Kv4.3, and Kv9.3) in PASMCs but not in mesenteric artery (MA) SMCs. Consistently, chronic hypoxia attenuated protein expression of Kv1.1, Kv1.5, and Kv2.1; reduced KV current [I(KV)]; caused E(m) depolarization; and increased ([Ca2+](cyt)) in PASMCs but negligibly affected KV channel expression, increased I(KV), and induced hyperpolarization in MASMCs. These results demonstrate that chronic hypoxia selectively downregulates KV channel expression, reduces I(KV), and induces E(m) depolarization in PASMCs. The subsequent rise in ([Ca2+](cyt)) plays a critical role in the development of pulmonary vasoconstriction and medial hypertrophy. The divergent effects of hypoxia on KV channel alpha-subunit mRNA expression in PASMCs and MASMCs may result from different mechanisms involved in the regulation of KV channel gene expression.
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Affiliation(s)
- O Platoshyn
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, UCSD Medical Center, 200 W. Arbor Dr., San Diego, CA 92103-8382, USA
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66
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Halayko AJ, Solway J. Molecular mechanisms of phenotypic plasticity in smooth muscle cells. J Appl Physiol (1985) 2001; 90:358-68. [PMID: 11133929 DOI: 10.1152/jappl.2001.90.1.358] [Citation(s) in RCA: 193] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Morphological, functional, molecular and cell biology studies have revealed a striking multifunctional nature of individual smooth muscle cells (SMC). SMCs manifest phenotypic plasticity in response to changes in environment and functional requirements, acquiring a range of structural and functional properties bounded by two extremes, called "synthetic" and "contractile." Each phenotypic state is characterized by expression of a unique set of structural, contractile, and receptor proteins and isoforms that correlate with differing patterns of gene expression. Recent studies have identified signaling pathways and transcription factors (e.g., RhoA GTPase/ROCK, also known as Rho kinase, and serum response factor) that regulate the transcriptional activities of genes encoding proteins associated with the contractile apparatus. Mechanical plasticity of contractile-state smooth muscle further extends SMC functional diversity. This may also be regulated, in part, by the RhoA GTPase/ROCK pathway, via reorganization of cytoskeletal and contractile proteins. Future studies that define transcriptional and posttranscriptional mechanisms of SMC plasticity are necessary to fully understand the role of SMC in the pathogenesis and morbidity of human diseases of the airways, vasculature, and gastrointestinal tract.
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Affiliation(s)
- A J Halayko
- Department of Physiology and Section of Respiratory Diseases, University of Manitoba, Winnipeg, Manitoba, Canada R3A 1R8.
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67
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Arciniegas E, Graterol A, Sànchez F. Characterization of nonmuscle cells present in the intima of normal adult bovine pulmonary artery. THE ANATOMICAL RECORD 2000; 258:262-8. [PMID: 10705346 DOI: 10.1002/(sici)1097-0185(20000301)258:3<262::aid-ar5>3.0.co;2-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
In this study, the presence of cells in the intimal region of normal adult bovine pulmonary artery (BPA) was examined by analysis of longitudinal sections at the level of light and transmission electron microscopy. In addition, the morphological and immunohistochemical phenotype of these cells as well as the presence of particular extracellular matrix (ECM) components in this region were also determined. Since ECM production and cell proliferation have been demonstrated to be regulated by locally released growth factors such as transforming growth factor beta (TGFbeta), the presence of TGFbeta-1 in this region was also investigated. Our findings reveal the presence of immature or "nonmuscle" cells into the subendothelial space of normal adult BPA. These cells were characterized by the presence of abundant cytoplasmic organelles and scanty microfilaments. Such cells were negative to antibodies against smooth muscle alpha actin (SM alpha-actin), 1E12, and vWf, but not to vimentin. Similar cells have recently been detected in normal adult BPA and canine carotid arteries, but in the medial region. Because of their location in these elastic arteries, the nonmuscle cells are involved not only in the remodeling of the medial region, but also in the neointima or intimal thickening formation by migration from the media to the subendothelial space, where they proliferate and secrete ECM components. However, a limited number of morphological studies and the current investigation describe the presence of scattered nonmuscle cells within the intima of some normal elastic arteries. This would suggest an important role for these resident cells within the intima in normal and pathological processes as well. In addition, our results show the presence, in this region, of TGFbeta-1 and of ECM components that include collagen, elastin, fibronectin, and laminin which are present in normal conditions and during the intima formation in vivo.
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Affiliation(s)
- E Arciniegas
- Instituto de Biomedicina, Facultad de Medicina, Universidad Central de Venezuela, Laboratorio de Microscopia Electrónica, Caracas 1010-A, Venezuela.
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68
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Stenmark KR, Frid M, Nemenoff R, Dempsey EC, Das M. Hypoxia induces cell-specific changes in gene expression in vascular wall cells: implications for pulmonary hypertension. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2000; 474:231-58. [PMID: 10635005 DOI: 10.1007/978-1-4615-4711-2_19] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
Mammals respond to reduced oxygen concentrations (hypoxia) in many different ways at the systemic, local, cellular and molecular levels. Within the pulmonary circulation, exposure to chronic hypoxia has been demonstrated to illicit increases in pulmonary artery pressure as well as dramatic structural changes in both large and small vessels. It has become increasingly clear that the response to hypoxia in vivo is differentially regulated at the level of specific cell types within the vessel wall. For instance, in large pulmonary blood vessels there is now convincing evidence to suggest that the medial layer is made up of many different subpopulations of smooth muscle cells. In response to hypoxia there are remarkable differences in the proliferative and matrix producing responses of these cells to the hypoxic environment. Some cell populations proliferate and increase matrix protein synthesis, while in other cell populations no apparent change in the proliferative or differentiation state of the cell takes place. In more peripheral vessels, the predominant proliferative changes in response to hypoxia in the pulmonary circulation occur in the adventitial layer rather than in the medial layer. Here again, specific increases in proliferation and matrix protein synthesis take place. Accumulating evidence suggests that the unique responses exhibited by specific cell types of hypoxia in vivo can be modeled in vitro. We have isolated, in culture, specific medial cell populations which demonstrate significant increases in proliferation in response to hypoxia, and others which exhibit no change or, in fact, a decrease in proliferation under hypoxic conditions. We have also isolated and cloned several unique populations of adventitial fibroblasts. There is good evidence that only certain fibroblast populations are capable of responding to hypoxia with an increase in proliferation. We have begun to elucidate the signaling pathways which are activated in those cell populations that exhibit proliferative responses to hypoxia. We show that hypoxia, in the absence of serum or mitogens, specifically activates select members of the protein kinase C isozyme family, as well as members of the mitogen-activated protein kinase (MAPK) family of proteins. This selective activation appears to take place in response to hypoxia only in those cells exhibiting a proliferative response, and antagonists of this pathway inhibit the response. Thus, there appear to be cells within each organ that demonstrate unique responses to hypoxia. A better understanding of why these cells exist and how they specifically transduce hypoxia-mediated signals will lead to a better understanding of how the changes in the pulmonary circulation take place under conditions of chronic hypoxia.
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Affiliation(s)
- K R Stenmark
- Department of Pediatrics, University of Colorado Health Sciences Center, Denver 80262, USA
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69
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Zaugg P, Djonov V, Füchtbauer EM, Draeger A. Sorting of murine vascular smooth muscle cells during wound healing in the chicken chorioallantoic membrane. Exp Cell Res 1999; 253:599-606. [PMID: 10585283 DOI: 10.1006/excr.1999.4712] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The vascular wall is built up of a heterogeneous population of smooth muscle cells, which exhibit not only morphological distinctions but also important differences in the composition of their structural and contractile proteins. "Epithelioid" smooth muscle cells correspond to an intimal-like type and display features associated with immaturity, whereas "spindle-shaped" cells closely resemble the more typical medial smooth muscle population. We have investigated the integration of these two cell types into the vascular architecture of an in vivo wound-healing model. Stably transfected with the beta-galactosidase gene, intima- and media-like cells were injected intravenously into the chicken chorioallantoic membrane, within which superficial foci of granulation tissue had been created by thermal or chemical injury. At 24 to 72 h after injection, cells had honed in on the lesion sites and were observed in juxtaposition to the endothelial lining of the capillaries. They began to deposit laminin, thereby indicating an impending role in the formation of the vascular wall. Intima- and media-like smooth muscle cells did not differ in their capacity to associate with capillaries, and, in so doing, their biochemical lineage characteristics became indistinguishable from one another. However, intima-like cells also penetrated the adventitial and medial layers of arteries. These findings reveal vascular smooth muscle cells to possess an extraordinary degree of plasticity, being able to adapt flexibly to changes in functional demands.
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Affiliation(s)
- P Zaugg
- Institute of Anatomy, University of Bern, Bühlstrasse 26, Bern, 3012, Switzerland
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70
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Frid MG, Aldashev AA, Nemenoff RA, Higashito R, Westcott JY, Stenmark KR. Subendothelial cells from normal bovine arteries exhibit autonomous growth and constitutively activated intracellular signaling. Arterioscler Thromb Vasc Biol 1999; 19:2884-93. [PMID: 10591665 DOI: 10.1161/01.atv.19.12.2884] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The arterial media is comprised of heterogeneous smooth muscle cell (SMC) subpopulations with markedly different growth responses to pathophysiological stimuli. Little information exists regarding the intracellular signaling pathways that contribute to these differences. Therefore, we investigated the growth-related signaling pathways in a unique subset of subendothelial SMCs (L1 cells) from normal, mature, bovine arteries and compared them with those in "traditional" SMCs derived from the middle media (L2 SMCs). Subendothelial L1 cells exhibited serum-independent autonomous growth, not observed in L2 SMCs. Autonomous growth of L1 cells was driven largely by the constitutively activated extracellular signal-regulated kinase (ERK-1/2) cascade. Inhibition of upstream activators of ERKs (MAP kinase kinase-1, p21(ras), receptor tyrosine kinases, and Gi protein-coupled receptors) led to suppression of autonomous growth in these cells. L1 cells also exhibited constitutive activation of important downstream targets of ERKs (cytosolic phospholipase A(2), cyclooxygenase-2) and secreted large amounts of prostaglandins. Importantly, L1 cells secreted potent mitogenic factor(s), which could potentially contribute in an autocrine fashion to the constitutive activation of these cells. Our data suggest that unique arterial cells with autonomous growth potential and constitutively activated signaling pathways exist in normal arteries and may contribute selectively to the pathogenesis of vascular diseases.
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MESH Headings
- Angiotensin II/pharmacology
- Animals
- Anticoagulants/pharmacology
- Aorta, Thoracic/cytology
- Becaplermin
- Blood Proteins/pharmacology
- Cattle
- Cell Division/drug effects
- Cell Division/physiology
- Cell Size/physiology
- Culture Media, Conditioned/pharmacology
- Culture Media, Serum-Free/pharmacology
- Cyclooxygenase 2
- Dinoprostone/biosynthesis
- Endothelin-1/pharmacology
- Endothelium, Vascular/cytology
- Endothelium, Vascular/enzymology
- Epoprostenol/biosynthesis
- GTP-Binding Proteins/agonists
- GTP-Binding Proteins/antagonists & inhibitors
- GTP-Binding Proteins/metabolism
- Gene Expression Regulation, Enzymologic
- Isoenzymes/metabolism
- MAP Kinase Signaling System/drug effects
- MAP Kinase Signaling System/physiology
- Mitogen-Activated Protein Kinase 1/genetics
- Mitogen-Activated Protein Kinase 1/metabolism
- Mitogen-Activated Protein Kinase 3
- Mitogen-Activated Protein Kinases/genetics
- Mitogen-Activated Protein Kinases/metabolism
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/enzymology
- Paracrine Communication/drug effects
- Paracrine Communication/physiology
- Phospholipases A/metabolism
- Platelet-Derived Growth Factor/pharmacology
- Prostaglandin-Endoperoxide Synthases/metabolism
- Proto-Oncogene Proteins c-sis
- Pulmonary Artery/cytology
- Tunica Media/cytology
- Vasoconstrictor Agents/pharmacology
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Affiliation(s)
- M G Frid
- Developmental Lung Biology Research Laboratory, Department of Pediatrics, University of Colorado Health Sciences Center, Denver 80262, USA.
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71
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Cooper AL, Beasley D. Hypoxia stimulates proliferation and interleukin-1alpha production in human vascular smooth muscle cells. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 277:H1326-37. [PMID: 10516167 DOI: 10.1152/ajpheart.1999.277.4.h1326] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Several lines of evidence indicate that hypoxia is a stimulus to vascular smooth muscle cell (VSMC) proliferation that occurs in pulmonary hypertension. The present study tested the hypothesis that low O(2) tension directly stimulates human VSMC proliferation by inducing them to produce interleukin (IL)-1, a potent autocrine growth factor for human VSMC. Human VSMC derived from pulmonary artery, aorta, or saphenous vein were incubated in either a normal in vitro O(2) environment (20% O(2)) or in chambers containing low (approximately 1%) or moderate (5%) O(2). Levels of IL-1alpha and IL-1beta mRNA increased in human VSMC after 24-48 h of incubation in low O(2) compared with levels in normoxic cells and then decreased upon subsequent reoxygenation. Levels of cell-associated IL-1alpha also increased progressively after 24-48 h in low O(2); however, detectable IL-1alpha was not released from the cells in the media. IL-1beta was detectable in cell lysates and supernatants; however, the levels were not affected by exposure to low O(2). mRNA encoding for tumor necrosis factor-alpha (TNF-alpha), a related cytokine and VSMC mitogen, was not detectable in human VSMC exposed to either low or 20% O(2). Proliferation of human VSMC was not stimulated during exposure to low O(2), despite the fact that cells remained responsive to the mitogenic effect of exogenous IL-1. Interestingly, however, exposure to 5% O(2) enhanced proliferation of human VSMC but did not induce IL-1alpha production. Inhibition of IL-1 binding to the type I IL-1 receptor by exogenous addition of IL-1-receptor antagonist (10 microgram/ml) did not attenuate the proliferation rates of human VSMC incubated in 20%, 5%, or low O(2) or in human VSMC that were reoxygenated after exposure to low O(2). These results demonstrate two direct and distinct effects of hypoxia on VSMC. Exposure to moderately low O(2) tension induces VSMC proliferation, independent of IL-1, whereas exposure to very low O(2) tension induces production of IL-1alpha.
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Affiliation(s)
- A L Cooper
- Division of Nephrology, Department of Medicine, New England Medical Center Hospitals, Boston, Massachusetts 02111, USA
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72
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Li S, Sims S, Jiao Y, Chow LH, Pickering JG. Evidence from a novel human cell clone that adult vascular smooth muscle cells can convert reversibly between noncontractile and contractile phenotypes. Circ Res 1999; 85:338-48. [PMID: 10455062 DOI: 10.1161/01.res.85.4.338] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Smooth muscle cells (SMCs) perform diverse functions that can be categorized as contractile and synthetic. A traditional model holds that these distinct functions are performed by the same cell, by virtue of its capacity for bidirectional modulation of phenotype. However, this model has been challenged, in part because there is no physiological evidence that an adult synthetic SMC can acquire the ability to contract. We sought evidence for this by cloning adult SMCs from human internal thoracic artery. One clone, HITB5, expressed smooth muscle alpha-actin, smooth myosin heavy chains, heavy caldesmon, and calponin and showed robust calcium transients in response to histamine and angiotensin II, which confirmed intact transmembrane signaling cascades. On serum withdrawal, these cells adopted an elongated and spindle-shaped morphology, random migration slowed, extracellular matrix protein production fell, and cell proliferation and [(3)H]thymidine incorporation fell to near 0. Cell viability was not compromised, however; in fact, apoptosis rate fell significantly. In this state, agonist-induced elevation of cytoplasmic calcium was even more pronounced and was accompanied by SMC contraction. Readdition of 10% serum completely returned HITB5 cells to a noncontractile, proliferative phenotype. Contractile protein expression increased after serum withdrawal, although modestly, which suggested that the switch to contractile function involved reorganization or sensitization of existing contractile structures. To our knowledge, the physiological properties of HITB5 SMCs provide the first direct demonstration that cultured human adult SMCs can convert between a synthetic, noncontracting state and a contracting state. HITB5 cells should be valuable for characterizing the basis of this critical transition.
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Affiliation(s)
- S Li
- Vascular Biology Group, John P. Robarts Research Institute
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73
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Stenmark KR, Frid M, Weiser-Evans M, Aldashev A, Nemenoff R. Contribution of Unique SMC Subpopulations to Vascular Disease. J Vasc Interv Radiol 1999. [DOI: 10.1016/s1051-0443(99)70146-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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74
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Bornfeldt KE, Krebs EG. Crosstalk between protein kinase A and growth factor receptor signaling pathways in arterial smooth muscle. Cell Signal 1999; 11:465-77. [PMID: 10405757 DOI: 10.1016/s0898-6568(99)00020-0] [Citation(s) in RCA: 92] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Crosstalk between the cyclic AMP-dependent protein kinase (PKA) and growth factor receptor signaling is one of many emerging concepts of crosstalk in signal transduction. Understanding of PKA crosstalk may have important implications for studies of crosstalk between other, less well known, signaling pathways. This review focuses on PKA crosstalk in arterial smooth muscle. Proliferation and migration of arterial smooth muscle cells (SMCs) contribute to the thickening of the blood vessel wall that occurs in many types of cardiovascular disease. PKA potently inhibits SMC proliferation by antagonizing the major mitogenic signaling pathways induced by growth factors in SMCs. PKA also inhibits growth factor-induced SMC migration. An intricate crosstalk between PKA and the mitogen-activated protein kinase (MAPK/ERK) pathway, the p70 S6 kinase pathway and cyclin-dependent kinases has been described. Further, PKA regulates expression of growth regulatory molecules. The result of PKA activation in SMCs is the potent inhibition of cell cycle traverse and SMC migration. In this review, we discuss recent advances in our understanding of the crosstalk between PKA and signaling pathways induced by growth factor receptors in SMCs, and where relevant, in other cell types in which interesting examples of PKA crosstalk have been described.
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Affiliation(s)
- K E Bornfeldt
- Department of Pathology, University of Washington, Seattle 98195-7470, USA.
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75
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Special communicationthe critical role of mechanical forces in blood vessel development, physiology and pathology. J Vasc Surg 1999; 29:1104-51. [PMID: 10359945 DOI: 10.1016/s0741-5214(99)70252-1] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The following extended abstracts were presented at the Research Initiatives in Vascular Disease Conference, Movers and Shakers in the Vascular Tree-Hemodynamic and Biomechanical Factors in Blood Vessel Pathology, sponsored by The Lifeline Foundation and the Cardiovascular & Interventional Radiology Research and Educational Foundation; jointly sponsored by the International Society for Cardiovascular Surgery, North American Chapter, The Society for Vascular Surgery, and The Society of Cardiovascular and Interventional Radiology; in cooperation with the National Institutes of Health-National Heart, Lung &Blood Institute on Mar 11-12, 1999, in Bethesda, Md.
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76
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Sartore S, Franch R, Roelofs M, Chiavegato A. Molecular and cellular phenotypes and their regulation in smooth muscle. Rev Physiol Biochem Pharmacol 1999; 134:235-320. [PMID: 10087911 DOI: 10.1007/3-540-64753-8_6] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- S Sartore
- Department of Biomedical Sciences, University of Padua, Italy
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77
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Huang W, Shen Z, Huang NE, Fung YC. Nonlinear indicial response of complex nonstationary oscillations as pulmonary hypertension responding to step hypoxia. Proc Natl Acad Sci U S A 1999; 96:1834-9. [PMID: 10051555 PMCID: PMC26697 DOI: 10.1073/pnas.96.5.1834] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
This paper is devoted to the quantization of the degree of nonlinearity of the relationship between two biological variables when one of the variables is a complex nonstationary oscillatory signal. An example of the situation is the indicial responses of pulmonary blood pressure (P) to step changes of oxygen tension (DeltapO2) in the breathing gas. For a step change of DeltapO2 beginning at time t1, the pulmonary blood pressure is a nonlinear function of time and DeltapO2, which can be written as P(t-t1 | DeltapO2). An effective method does not exist to examine the nonlinear function P(t-t1 | DeltapO2). A systematic approach is proposed here. The definitions of mean trends and oscillations about the means are the keys. With these keys a practical method of calculation is devised. We fit the mean trends of blood pressure with analytic functions of time, whose nonlinearity with respect to the oxygen level is clarified here. The associated oscillations about the mean can be transformed into Hilbert spectrum. An integration of the square of the Hilbert spectrum over frequency yields a measure of oscillatory energy, which is also a function of time, whose mean trends can be expressed by analytic functions. The degree of nonlinearity of the oscillatory energy with respect to the oxygen level also is clarified here. Theoretical extension of the experimental nonlinear indicial functions to arbitrary history of hypoxia is proposed. Application of the results to tissue remodeling and tissue engineering of blood vessels is discussed.
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Affiliation(s)
- W Huang
- Department of Bioengineering, University of California at San Diego, La Jolla, CA 92093-0412, USA
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78
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Huang W, Shen Z, Huang NE, Fung YC. Use of intrinsic modes in biology: examples of indicial response of pulmonary blood pressure to +/- step hypoxia. Proc Natl Acad Sci U S A 1998; 95:12766-71. [PMID: 9788987 PMCID: PMC23580 DOI: 10.1073/pnas.95.22.12766] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Recently, a new method to analyze biological nonstationary stochastic variables has been presented. The method is especially suitable to analyze the variation of one biological variable with respect to changes of another variable. Here, it is illustrated by the change of the pulmonary blood pressure in response to a step change of oxygen concentration in the gas that an animal breathes. The pressure signal is resolved into the sum of a set of oscillatory intrinsic mode functions, which have zero "local mean," and a final nonoscillatory mode. With this device, we obtain a set of "mean trends," each of which represents a "mean" in a definitive sense, and together they represent the mean trend systematically with different degrees of oscillatory content. Correspondingly, the oscillatory content of the signal about any mean trend can be represented by a set of partial sums of intrinsic mode functions. When the concept of "indicial response function" is used to describe the change of one variable in response to a step change of another variable, we now have a set of indicial response functions of the mean trends and another set of indicial response functions to describe the energy or intensity of oscillations about each mean trend. Each of these can be represented by an analytic function whose coefficients can be determined by a least-squares curve-fitting procedure. In this way, experimental results are stated sharply by analytic functions.
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Affiliation(s)
- W Huang
- Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093-0412, USA
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79
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Abstract
The vascular and visceral smooth muscle tissues of the lung perform a number of tasks that are critical to pulmonary function. Smooth muscle function often is compromised as a result of lung disease. Though a great deal is known about regulation of smooth muscle cell replication and cell and tissue contractility, much less is understood regarding the phenotype of the contractile protein machinery of lung smooth muscle cells. This review focuses on the expression of cytoskeletal and contractile proteins of lung vascular and airway smooth muscle cells during development, in the adult and during vascular and airway remodeling. Emphasis is placed on the expression of the heavy chain of smooth muscle myosin, as well as the regulation of its gene. Important areas for future research are discussed.
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Affiliation(s)
- R B Low
- Department of Molecular Physiology and Biophysics, University of Vermont, Burlington 05405-0068, USA.
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80
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Stenmark KR, Frid MG. Smooth muscle cell heterogeneity: role of specific smooth muscle cell subpopulations in pulmonary vascular disease. Chest 1998; 114:82S-90S. [PMID: 9676647 DOI: 10.1378/chest.114.1_supplement.82s] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
MESH Headings
- Animals
- Aorta/cytology
- Cell Differentiation
- Cells, Cultured
- Cloning, Molecular
- Humans
- Hypertension, Pulmonary/pathology
- Hypertension, Pulmonary/physiopathology
- Muscle Proteins/metabolism
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/pathology
- Muscle, Smooth, Vascular/physiology
- Phenotype
- Pulmonary Artery/pathology
- Signal Transduction/physiology
- Tunica Intima/cytology
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Affiliation(s)
- K R Stenmark
- University of Colorado Health Sciences Center, Developmental Lung Biology Laboratory, Denver 80205, USA
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81
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Dempsey EC, Das M, Frid MG, Xu Y, Stenmark KR. Hypoxic growth of bovine pulmonary artery smooth muscle cells: dependence on synergy, heterogeneity, and injury-induced phenotypic change. Chest 1998; 114:29S-30S. [PMID: 9676612 DOI: 10.1378/chest.114.1_supplement.29s] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Affiliation(s)
- E C Dempsey
- Cardiovascular Pulmonary and Developmental Biology Research Laboratories, University of Colorado Health Sciences Center, Denver VA Medical Center, USA
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82
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Frid MG, Aldashev AA, Cabirac GF, Dempsey EC, Stenmark KR. Hypoxia stimulates proliferation of a unique cell population isolated from the bovine vascular media. Chest 1998; 114:28S-29S. [PMID: 9676611 DOI: 10.1378/chest.114.1_supplement.28s] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Affiliation(s)
- M G Frid
- Department of Developmental Lung Biology, University of Colorado Health Sciences Center, Denver, USA
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83
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van Suylen RJ, Smits JF, Daemen MJ. Pulmonary artery remodeling differs in hypoxia- and monocrotaline-induced pulmonary hypertension. Am J Respir Crit Care Med 1998; 157:1423-8. [PMID: 9603118 DOI: 10.1164/ajrccm.157.5.9709050] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
In the present study we analyzed structural characteristics of muscular pulmonary arteries and arterioles in two classic models of pulmonary hypertension, the rat hypoxia and monocrotaline models. We hypothesized that an increase in medial cross-sectional area would result in reduction of the lumen area and that these parameters would correlate with the increase in pulmonary artery pressure (PAP). Four weeks after a single injection of monocrotaline (MCT) or after 4 wk of hypoxic exposure the rats were killed. Both MCT and chronic hypoxia induced right ventricular hypertrophy. In separate groups of rats both MCT and chronic hypoxia increased PAP. MCT increased the media cross-sectional area of pulmonary arteries with an external diameter between 30-100 microm and 101-200 microm and reduced the lumen area of pulmonary arteries with an external diameter between 101-200 microm. Chronic hypoxia only slightly increased the media cross-sectional area without a change of the lumen area. Both MCT and hypoxia increased the percentage of partly muscularized and muscularized arterioles. The angiotensin-converting enzyme (ACE) inhibitor captopril (0.5 mg/kg/h) had no effect on MCT-induced pulmonary hypertension, right ventricular hypertrophy, and pulmonary artery remodeling. In chronic hypoxic rats it prevented an increase in medial cross-sectional area of pulmonary arteries with an external diameter between 30-100 microm and attenuated the increase in the percentage of muscularized arterioles, without any effect on the PAP. We conclude that MCT, in contrast to chronic hypoxia, induces structural changes of muscular pulmonary arteries with an external diameter between 101-200 microm which may contribute to an increased PAP and right ventricular hypertrophy. These data also suggest that angiotensin II plays a pivotal role in remodeling of pulmonary arteries in hypoxia but not in MCT-induced pulmonary hypertension.
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Affiliation(s)
- R J van Suylen
- Department of Pathology, Cardiovascular Research Institute Maastricht, Maastricht University, The Netherlands
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84
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Frid MG, Aldashev AA, Dempsey EC, Stenmark KR. Smooth muscle cells isolated from discrete compartments of the mature vascular media exhibit unique phenotypes and distinct growth capabilities. Circ Res 1997; 81:940-52. [PMID: 9400374 DOI: 10.1161/01.res.81.6.940] [Citation(s) in RCA: 139] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Heterogeneity of smooth muscle cell (SMC) phenotype and function is rapidly emerging as an important concept. We have recently described that phenotypically distinct SMC subpopulations in bovine pulmonary arteries exhibit unique proliferative and matrix-producing responses to hypoxic pulmonary hypertension. To provide better understanding of the molecular mechanisms contributing to this phenomenon, experimental studies will require a reliable in vitro model. The purpose of the present study was first to determine if distinct SMC subpopulations, similar to those observed in vivo, could be selectively isolated from the mature arterial media, and then to evaluate whether select SMC subpopulations would exhibit heightened responses to growth-promoting stimuli and hypoxia. We were able to reproducibly isolate at least four phenotypically unique cell subpopulations from the inner, middle, and outer compartments of the arterial media. Differences in cell phenotype were demonstrated by morphological appearance and differential expression of muscle-specific proteins. The isolated cell subpopulations exhibited markedly different growth capabilities. Two SMC subpopulations grew slowly in 10% serum and were quiescent in plasma-based medium. The other two cell subpopulations, exhibiting nonmuscle characteristics, grew rapidly in 10% serum and proliferated in plasma-based medium and in response to hypoxia. Certain colonies of the nonmuscle-like cell subpopulations were found to grow autonomously under serum-deprived conditions and to secrete mitogenic factors. Our data, demonstrating that phenotypically distinct cells with enhanced growth potential exist within the normal arterial media, support the idea that these unique cells could contribute selectively to the pathogenesis of vascular disease.
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Affiliation(s)
- M G Frid
- Developmental Lung Biology Research, University of Colorado Health Sciences Center, Denver 80262, USA.
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85
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Sahai A, Mei C, Pattison TA, Tannen RL. Chronic hypoxia induces proliferation of cultured mesangial cells: role of calcium and protein kinase C. THE AMERICAN JOURNAL OF PHYSIOLOGY 1997; 273:F954-60. [PMID: 9435685 DOI: 10.1152/ajprenal.1997.273.6.f954] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The effect of hypoxia on the proliferation of cultured rat mesangial cells was examined. To evaluate the underlying signaling mechanisms, the roles of intracellular calcium ([Ca2+]i) and protein kinase C (PKC) were determined. Quiescent cultures were exposed to hypoxia (3% O2) or normoxia (18% O2), and [3H]thymidine incorporation, cell number, [Ca2+]i, and PKC were assessed. Mesangial cells exposed to 28 h of hypoxia exhibited a significant increase in [3H]thymidine incorporation followed by a significant increase in cell number at 72 h in comparison with respective normoxic controls. Hypoxia induced a biphasic activation of PKC, reflected by translocation of the enzyme activity from cytosol to membrane at 1 h, a return to baseline at 4 and 8 h, with subsequent reactivation from 16 to 48 h. In addition, hypoxia-induced proliferation was prevented by a PKC inhibitor 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H-7). Cells exposed to hypoxia produced progressive increases in resting [Ca2+]i from 15 to 60 min which remain sustained up to 24 h of examination. Verapamil significantly prevented the hypoxia-induced proliferation, and both verapamil treatment and incubations in a calcium-free medium for 1 h blocked the hypoxia-induced stimulation of [Ca2+]i as well as PKC. These results provide the first in vitro evidence that chronic hypoxia induces proliferation of cultured glomerular mesangial cells, which is mediated by the stimulation of [Ca2+]i and the subsequent activation of PKC.
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Affiliation(s)
- A Sahai
- Division of Renal Diseases and Hypertension, University of Colorado Health Sciences Center, Denver 80262, USA
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86
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Seidel CL. Cellular heterogeneity of the vascular tunica media. Implications for vessel wall repair. Arterioscler Thromb Vasc Biol 1997; 17:1868-71. [PMID: 9351347 DOI: 10.1161/01.atv.17.10.1868] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- C L Seidel
- Department of Medicine, Baylor College of Medicine, Houston, Tex. 77030, USA.
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87
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Seligman SP, Nishiwaki T, Kadner SS, Dancis J, Finlay TH. Hypoxia stimulates ecNOS mRNA expression by differentiated human trophoblasts. Ann N Y Acad Sci 1997; 828:180-7. [PMID: 9329838 DOI: 10.1111/j.1749-6632.1997.tb48538.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Cytotrophoblasts isolated from normal human placenta cultured under normoxic conditions (20% O2, pO2 = 130 mmHg) for 48-72 h differentiate to a form which expresses high levels of hCG and which morphologically resembles syncytiotrophoblast. We had previously shown that hypoxia (0-1% O2, pO2 = 12-14 mmHg) blocks this differentiation process, although trophoblasts exposed to hypoxia for up to 96 h were completely viable. In this article we showed that trophoblast responds to hypoxia by expressing the hypoxia-sensitive DNA binding protein HIF-1. We also showed that in trophoblast cultured under normoxic conditions, expression of endothelial cell nitric oxide synthase (ecNOS) mRNA increases with time, reaching a maximum in 48-72 h. However, in trophoblast maintained under hypoxic conditions for 48 h (after an initial 24 h in normoxia), expression of ecNOS mRNA is greatly reduced. These observations are consistent with the expression of ecNOS by syncytiotrophoblast but not by cytotrophoblast. In contrast, exposure of differentiated trophoblasts to hypoxia for 24 h (after 48-72 h in normoxia) significantly stimulates expression of ecNoS mRNA over that of cells maintained continuously in normoxia. These results suggest that in differentiated trophoblast hypoxia can stimulate ecNOS expression.
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Affiliation(s)
- S P Seligman
- Department of Obstetrics and Gynecology, New York University Medical Center, New York 10016, USA
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88
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Moiseeva EP, Critchley DR. Characterisation of the promoter which regulates expression of a phosphoglucomutase-related protein, a component of the dystrophin/utrophin cytoskeleton predominantly expressed in smooth muscle. EUROPEAN JOURNAL OF BIOCHEMISTRY 1997; 248:634-43. [PMID: 9342213 DOI: 10.1111/j.1432-1033.1997.00634.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We have recently characterised a 60-kDa muscle-specific phosphoglucomutase-related protein (PGM-RP) which is expressed predominantly in adult visceral and vascular smooth muscle. Here we show that the adult vascular smooth muscle cell line PAC1, which retains the capacity to synthesise metavinculin (a marker of the contractile phenotype) also expressed PGM-RP. However, an embryonic smooth muscle cell line A10, which lacks metavinculin, expressed low levels of PGM-RP. Levels of PGM-RP increased in quiescent PAC1 and A10 cells, and were elevated in response to angiotensin II. PGM-RP is therefore a good marker of the contractile/differentiated smooth muscle phenotype. We have sequenced 1.8 kb of the human PGM-RP promoter and shown that it lacks a conventional TATA box. There are multiple transcription start sites, the most predominant of which are inside an initiator sequence (Inr), which is close to two CT boxes and a GATA element. A minimal promoter-CAT construct (p57-CAT) containing the Inr, a CT box and GATA element directed high-level chloramphenicol acetyltransferase (CAT) expression in the differentiated smooth muscle cell line PAC1, and low-level expression in the embryonic smooth muscle cell line A10. This fits well with the pattern of expression of the endogenous gene. A construct (p146-CAT) containing all of the mRNA initiation sites directed a reduced level of CAT expression, and constructs containing 1.8 kb and 3.3 kb upstream of the major transcription start site displayed even lower activity. Sequence comparisons suggest that the PGM-RP promoter evolved from the main phosphoglucomutase promoter which is active in wide range of cell types. The PGM-RP promoter may have acquired negative regulatory elements as expression of the gene became muscle-specific.
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Affiliation(s)
- E P Moiseeva
- Department of Biochemistry, University of Leicester, UK
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89
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Murry CE, Gipaya CT, Bartosek T, Benditt EP, Schwartz SM. Monoclonality of smooth muscle cells in human atherosclerosis. THE AMERICAN JOURNAL OF PATHOLOGY 1997; 151:697-705. [PMID: 9284818 PMCID: PMC1857839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Atherosclerotic plaques contain a large monoclonal population of cells. Monoclonality could arise by somatic mutation, selection of a pre-existing lineage, or expansion of a pre-existing (developmental) clone. To determine the monoclonal cell type in plaque and learn when monoclonality arises, we studied X chromosome inactivation patterns using methylation of the X-linked human androgen receptor gene. Assays based on polymerase chain reaction were performed on samples of known cellular composition, microdissected from histological sections of human arteries. In atherosclerotic vessels, the majority of medial samples (7/11 coronary and 2/3 aortic) showed balanced (paternal and maternal) patterns of X inactivation, indicating polyclonality. In contrast, most samples of plaque smooth muscle cells showed a single pattern of X inactivation (3/4 aortic plaques and 9/11 coronary plaques; P < 0.01 versus media), indicating that plaque smooth muscle cells are monoclonal. Samples of plaque containing inflammatory or endothelial cells showed balanced X inactivation, also demonstrating polyclonality. Multiple plaques from a given patient showed no bias toward one allele, indicating there was no X-linked selection of cells during plaque growth. To determine whether plaques might arise from pre-existing clones (large X inactivation patches), we then studied 10 normal coronaries with diffuse intimal thickening. Six of the ten coronaries showed skewed X inactivation patterns in normal media and intima, suggesting the patch size in normal arteries is surprisingly large. Thus, smooth muscle cells constitute the monoclonal population in atherosclerotic plaques. The finding that normal arteries may have large X inactivation patches raises the possibility that plaque monoclonality may arise by expanding a pre-existing clone of cells rather than generating a new clone by mutation or selection.
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Affiliation(s)
- C E Murry
- Department of Pathology, University of Washington, Seattle 98195, USA.
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90
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Ma X, Li W, Stephens NL. Heterogeneity of airway smooth muscle at tissue and cellular levels. Can J Physiol Pharmacol 1997. [DOI: 10.1139/y97-105] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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91
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Halayko AJ, Rector E, Stephens NL. Characterization of molecular determinants of smooth muscle cell heterogeneity. Can J Physiol Pharmacol 1997. [DOI: 10.1139/y97-106] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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92
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Dempsey EC, Frid MG, Aldashev AA, Stenmark KR. Heterogeneity in the proliferative response of bovine pulmonary artery smooth muscle cells to mitogens and hypoxia: importance of protein kinase C. Can J Physiol Pharmacol 1997. [DOI: 10.1139/y97-104] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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93
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Pitsch RJ, Minion DJ, Goman ML, van Aalst JA, Fox PL, Graham LM. Platelet-derived growth factor production by cells from Dacron grafts implanted in a canine model. J Vasc Surg 1997; 26:70-8. [PMID: 9240324 DOI: 10.1016/s0741-5214(97)70149-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
PURPOSE Previous studies of grafts implanted in dogs documented a time-dependent increase in platelet-derived growth factor (PDGF) production that correlated with inner-capsule thickness. The purpose of this study was to identify the cells in vascular grafts that produce PDGF. METHODS Dacron thoracoabdominal grafts were seeded with autologous endothelial cells (ECs), implanted in 11 beagles, and removed after 4 or 20 weeks. ECs and smooth muscle cells (SMCs) were cultured from grafts and adjacent aorta, and PDGF in the conditioned media was measured by radioreceptor assay. The PDGF A-chain mRNA level in freshly harvested cells was assessed using reverse transcriptase, followed by polymerase chain reaction, and expressed as a ratio of glyceraldehyde-3-phosphate dehydrogenase signal. Localization of PDGF A-chain and B-chain protein was also examined with immunohistochemical analysis. RESULTS Graft and aortic ECs in primary culture did not produce significantly different amounts of PDGF in 72 hours, averaging 368 +/- 160 and 340 +/- 81 pg/microgram DNA, respectively. Graft SMCs in primary culture produced significantly more PDGF than aortic SMCs (584 +/- 343 and 113 +/- 94 pg/microgram DNA, respectively; p < 0.01). Graft SMC PDGF secretion remained greater than aortic SMC PDGF secretion through at least six cell passages. PDGF A-chain mRNA levels were not significantly different for aortic or graft ECs. The PDGF A-chain mRNA level was significantly higher for graft SMCs than aortic SMCs (2.44 +/- 0.67 and 1.45 +/- 0.57 pg/microgram, respectively; p < 0.03). Immunocytochemical analysis detected PDGF A-chain and B-chain protein in the ECs from both native aorta and graft as well as the subendothelial SMCs in the graft, but not in the SMCs of the native aorta. CONCLUSIONS These results suggest that graft SMCs are functionally altered, producing more PDGF than aortic SMCs. PDGF produced by graft SMCs may contribute to the development of intimal hyperplasia.
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Affiliation(s)
- R J Pitsch
- Department of Surgery, Case Western Reserve University, USA
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94
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Michelakis ED, Reeve HL, Huang JM, Tolarova S, Nelson DP, Weir EK, Archer SL. Potassium channel diversity in vascular smooth muscle cells. Can J Physiol Pharmacol 1997. [DOI: 10.1139/y97-111] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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95
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Frid MG, Dempsey EC, Durmowicz AG, Stenmark KR. Smooth muscle cell heterogeneity in pulmonary and systemic vessels. Importance in vascular disease. Arterioscler Thromb Vasc Biol 1997; 17:1203-9. [PMID: 9261247 DOI: 10.1161/01.atv.17.7.1203] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Experimental evidence is rapidly accumulating which demonstrates that the arterial media in both pulmonary and systemic vessels is not composed of a phenotypically homogeneous population of smooth muscle cells (SMCs) but rather of heterogeneous subpopulations of cells with unique developmental lineages. In vivo and in vitro observations strongly suggest that marked differences in the phenotype, growth, and matrix-producing capabilities of phenotypically distinct SMC subpopulations exist and that these differences are intrinsic to the cell type. These data also suggest that differential proliferative and matrix-producing capabilities of distinct SMC subpopulations govern, at least in part, the pattern of abnormal cell proliferation and matrix protein synthesis observed in the pathogenesis of vascular disease. Within the pulmonary circulation, the observation that the isolated medial SMC subpopulations exhibit differential proliferative responses to hypoxic exposure is important, since this in vitro cell-model system can now be used to better understand the mechanisms that regulate increased responsiveness of specific medial cell subpopulations to low oxygen concentrations. Our data also support the idea that protein kinase C is likely to be one important determinant of differential cell growth responses to hypoxia. The data also suggest differential involvement of specific arterial SMC subpopulations in the elastogenic responses of the vessel wall to injury. We believe that a better understanding of the mechanisms contributing to the unique behavior of specific arterial cell subpopulations will provide important future directions for therapies aimed at preventing abnormal cell replication and matrix protein synthesis in vascular disease.
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Affiliation(s)
- M G Frid
- Cardiovascular Pulmonary Laboratory, Denver 80262, USA
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96
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Absher PM, Schneider DJ, Baldor LC, Russell JC, Sobel BE. Increased proliferation of explanted vascular smooth muscle cells: a marker presaging atherogenesis. Atherosclerosis 1997; 131:187-94. [PMID: 9199271 DOI: 10.1016/s0021-9150(97)06104-2] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The JCR:LA-cp homozygous cp/cp corpulent rat is genetically predisposed to develop atherosclerosis evident after 9 and 18 months of age in males and females and to manifest metabolic derangements resembling those seen in type II diabetes in humans (hyperinsulinemia, insulin resistance, hyperglycemia and hypertriglyceridemia). The present study was undertaken to determine whether vascular smooth muscle cells (SMCs) explanted from vessels destined to become atherosclerotic later in life exhibit intrinsic properties ex vivo that presage atherogenesis to provide a means for evaluating promptly intervention designed to modify it. SMCs were cultured from aortic explants of JCR:LA-cp corpulent (cp/cp) and lean control (+/+) rats of 4, 5, 6, and 9 months of age. Compared with SMCs from controls, SMCs from cp/cp rats exhibited increased proliferation, higher saturation density, increased augmentation of proliferation in response to selected mitogens and greater adherence to extracellular matrix proteins. The increased proliferative activity ex vivo anteceded by several months the development of atherosclerotic lesions in vivo. Thus, it is a promising marker in assessments of the efficacy of interventions designed to retard or prevent atherosclerosis.
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MESH Headings
- Animals
- Aorta/pathology
- Arteriosclerosis/etiology
- Arteriosclerosis/metabolism
- Arteriosclerosis/pathology
- Blood Glucose/metabolism
- Cell Adhesion
- Cell Count
- Cell Division
- Cells, Cultured
- Diabetes Mellitus, Experimental/blood
- Diabetes Mellitus, Experimental/complications
- Extracellular Matrix Proteins/metabolism
- Female
- Insulin/blood
- Male
- Mitogens/pharmacology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Muscle, Smooth, Vascular/pathology
- Obesity/blood
- Obesity/complications
- Rats
- Rats, Zucker
- Triglycerides/blood
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Affiliation(s)
- P M Absher
- Department of Medicine, University of Vermont College of Medicine, Burlington 05405, USA
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97
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Liu SQ. Regression of hypoxic hypertension-induced changes in the elastic laminae of rat pulmonary arteries. J Appl Physiol (1985) 1997; 82:1677-84. [PMID: 9134919 DOI: 10.1152/jappl.1997.82.5.1677] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The elastic laminae of the pulmonary arteries (PAs) undergo a progressive structural change in hypoxic hypertension. This study focused on the reversibility of altered PA elastic laminae of the rat due to hypoxic hypertension. The structure and cross-sectional area of the PA medial elastic laminae were examined by using electron-microscopic and image-analytic approaches during recovery from 12 h and 10 days of hypoxic hypertension. At 12 h of hypoxic hypertension, the elastic laminae, which appeared homogeneous in normal control animals, were reorganized into structures composed of randomly oriented filaments, with an increase in the cross-sectional area of 70%. At 10 days of hypoxic hypertension, the elastic laminae appeared homogeneous in structure and normal in cross-sectional area despite continuous exposure to hypoxia. During recovery from 12 h of hypoxic hypertension, the medial elastic laminae regained their homogeneous structure and normal cross-sectional area after day 2. During recovery from 10 days of hypoxic hypertension, the medial elastic laminae changed from homogeneous to filamentous structures, with a progressively altered cross-sectional area that increased by 89% from recovery day 0 to day 10 and returned to the normal level on day 30. These changes were associated with alterations in the PA wall tensile stress. These results indicated that structural changes in the PA elastic laminae were reversible and that the regression process depended on the duration of exposure to hypoxia, the state of the elastic laminae, and possibly the tensile stress level in the PA wall.
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Affiliation(s)
- S Q Liu
- Biomedical Engineering Department, Northwestern, University, Evanston, Illinois 60208-3107, USA
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98
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Jones PL, Cowan KN, Rabinovitch M. Tenascin-C, proliferation and subendothelial fibronectin in progressive pulmonary vascular disease. THE AMERICAN JOURNAL OF PATHOLOGY 1997; 150:1349-60. [PMID: 9094991 PMCID: PMC1858188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Progressive pulmonary hypertension is characterized by smooth muscle cell proliferation and migration leading to occlusive arterial lesions. Previously, using cultured smooth muscle cells, we demonstrated that epidermal growth factor (EGF)-dependent proliferation and migration are dependent on tenascin-C (Tn) and cellular fibronectin (Fn), respectively. In this study we applied immunohistochemistry to lung biopsy tissue from patients with congenital heart defects and pulmonary hypertension to determine how the distribution and intensity of Tn, EGF, proliferating cell nuclear antigen (PCNA), and Fn expression related to arterial abnormalities. With mildly increased wall thickness, minimal Tn, PCNA, and EGF was evident. With progressive hypertrophy, moderately intense foci of Tn were apparent in the adventitia, periendothelium, and occasionally the media but not consistently co-distributing with EGF and PCNA. With obstructive lesions, intense neointimal Tn expression co-localized with EGF and PCNA. Fn accumulation in the periendothelium increased with medial hypertrophy and became more widespread in a diffuse pattern with neointimal formation. The neointima was predominantly composed of alpha-smooth-muscle-actin-positive cells, occasional inflammatory cells with no evidence of apoptosis. These studies are consistent with Tn modulating EGF-dependent neointimal smooth muscle cell proliferation and Fn providing a gradient for smooth muscle cell migration from media to neointima.
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Affiliation(s)
- P L Jones
- Division of Cardiovascular Research, Hospital for Sick Children, Toronto, Ontario, Canada
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Abstract
In many organs and tissues, the cellular response to injury is associated with a reiteration of specific developmental processes. Studies have shown that, in response to injury, vascular wall cells in adult organisms express genes or gene products characteristic of earlier developmental states. Other genes, expressed preferentially in adult cells in vivo, are down-regulated following injurious stimuli. Complicating matters, however, are recent observations demonstrating that the vascular wall is comprised of phenotypically heterogeneous subpopulations of endothelial cells, smooth muscle cells, and fibroblasts. It is unclear how specific subsets of cells respond to injury and thus contribute to the vascular remodeling that characterizes chronic pulmonary hypertension. This review discusses vascular development in the lung and the cellular responses occurring in pulmonary hypertension; special attention is given to heterogeneity of responses within cell populations and reiteration of developmental processes.
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Affiliation(s)
- K R Stenmark
- University of Colorado Health Sciences Center, Developmental Lung Biology Laboratory, Denver 80262, USA
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Jones PL, Rabinovitch M. Tenascin-C is induced with progressive pulmonary vascular disease in rats and is functionally related to increased smooth muscle cell proliferation. Circ Res 1996; 79:1131-42. [PMID: 8943951 DOI: 10.1161/01.res.79.6.1131] [Citation(s) in RCA: 122] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Tenascin-C, an extracellular matrix glycoprotein prominent during tissue remodeling, has been linked to cell migration, proliferation, and apoptosis. To determine its potential role in the pathobiology of pulmonary hypertension, we compared tenascin expression in adult and infant rat pulmonary arteries (PAs) after injection of the toxin monocrotaline. Immunohistochemistry, in situ hybridization, and Northern blot analysis demonstrated induction of tenascin in adult rat central and peripheral PA. Tenascin was not, however, detected in infant vessels, which show spontaneous regression of vascular lesions. To determine a function for tenascin, we correlated its expression with evidence of apoptosis and cell proliferation using the TdT-mediated dUTP-biotin nick end labeling (TUNEL) assay and 5-bromo-2'-deoxyuridine labeling, respectively. Apoptosis was observed only in the adult rat PA endothelial cell layer, preceding the induction of tenascin, which colocalized both temporally and spatially with proliferating smooth muscle cells (SMCs). A cause-and-effect relationship was documented in cultured rat PA SMCs, where tenascin promoted growth in response to basic fibroblast growth factor and was a prerequisite for epidermal growth factor-induced proliferation. These data provide novel functional information suggesting that endothelial cell apoptosis precedes progressive pulmonary hypertension and that induction of tenascin may be critical to growth factor-dependent SMC proliferation.
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Affiliation(s)
- P L Jones
- Division of Cardiovascular Research, Hospital for Sick Children, Toronto, Ontario, Canada
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