Effects of peroxynitrite on sarcoplasmic reticulum Ca2+ pump in pig coronary artery smooth muscle

2003 ◽  
Vol 284 (2) ◽  
pp. C294-C301 ◽  
Author(s):  
Ashok K. Grover ◽  
Sue E. Samson ◽  
Sarah Robinson ◽  
Chiu Yin Kwan
Keyword(s):  
Smooth Muscle ◽  
Coronary Artery ◽  
Sarcoplasmic Reticulum ◽  
Quaternary Structure ◽  
Ischemia Reperfusion ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Vesicular Membrane ◽  
Cardiac Muscles ◽  
Pig Coronary Artery

Peroxynitrite generated in arteries from superoxide and NO may damage Ca2+ pumps. Here, we report the effects of peroxynitrite on ATP-dependent azide-insensitive uptake of Ca2+ into pig coronary artery vesicular membrane fractions F2 [enriched in plasma membrane (PM)] and F3 [enriched in sarcoplasmic reticulum (SR)]. Membranes were pretreated with peroxynitrite and then with DTT to quench this agent. This pretreatment inhibited Ca2+ uptake in a peroxynitrite concentration-dependent manner, but the effect was more severe in F3 than in F2. The inhibition was thus not overcome by excess DTT used to quench peroxynitrite and was not affected if catalase, SOD, or mannitol was added along with peroxynitrite. Such damage to the pump protein would be difficult to repair if produced during ischemia-reperfusion. The acylphosphates formed with ATP in F3 corresponded mainly to the SR Ca2+ pump (110 kDa), but in F2 both PM (140 kDa) and 110-kDa bands were observed. Peroxynitrite treatment of F2 inhibited only the 110-kDa band. Inhibition of Ca2+ uptake and acylphosphate formation from ATP correlated well in peroxynitrite-treated F3 samples. However, inhibition of acylphosphates from orthophosphate (reverse reaction of the pump) was slightly poorer. Peroxynitrite treatment also covalently cross-linked the pump protein, yielding no dimers but only larger oligomers. In contrast, cross-linking of the SR Ca2+ pump in skeletal and cardiac muscles gives dimers as the first oligomers. Therefore, we speculate that SERCA2 has a different quaternary structure in the coronary artery smooth muscle.

G protein-coupled estrogen receptor 1 mediates relaxation of coronary arteries via cAMP/PKA-dependent activation of MLCP

2014 ◽  
Vol 307 (4) ◽  
pp. E398-E407 ◽  
Author(s):  
Xuan Yu ◽  
Fen Li ◽  
Enno Klussmann ◽  
John N. Stallone ◽  
Guichun Han
Keyword(s):  
Coronary Artery ◽  
Coronary Arteries ◽  
Ischemia Reperfusion ◽  
Inhibitory Effect ◽  
Regulatory Subunit ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Rhoa Activity ◽  
Vascular Regulation

Activation of GPER exerts a protective effect in hypertension and ischemia-reperfusion models and relaxes arteries in vitro. However, our understanding of the mechanisms of GPER-mediated vascular regulation is far from complete. In the current study, we tested the hypothesis that GPER-induced relaxation of porcine coronary arteries is mediated via cAMP/PKA signaling. Our findings revealed that vascular relaxation to the selective GPER agonist G-1 (0.3–3 μM) was associated with increased cAMP production in a concentration-dependent manner. Furthermore, inhibition of adenylyl cyclase (AC) with SQ-22536 (100 μM) or of PKA activity with either Rp-8-CPT-cAMPS (5 μM) or PKI (5 μM) attenuated G-1-induced relaxation of coronary arteries preconstricted with PGF2α (1 μM). G-1 also increased PKA activity in cultured coronary artery smooth muscle cells (SMCs). To determine downstream signals of the cAMP/PKA cascade, we measured RhoA activity in cultured human and porcine coronary SMCs and myosin-light chain phosphatase (MLCP) activity in these artery rings by immunoblot analysis of phosphorylation of myosin-targeting subunit protein-1 (p-MYPT-1; the MLCP regulatory subunit). G-1 decreased PGF2α-induced p-MYPT-1, whereas Rp-8-CPT-cAMPS prevented this inhibitory effect of G-1. Similarly, G-1 inhibited PGF2α-induced phosphorylation of MLC in coronary SMCs, and this inhibitory effect was also reversed by Rp-8-CPT-cAMPS. RhoA activity was downregulated by G-1, whereas G36 (GPER antagonist) restored RhoA activity. Finally, FMP-API-1 (100 μM), an inhibitor of the interaction between PKA and A-kinase anchoring proteins (AKAPs), attenuated the effect of G-1 on coronary artery relaxation and p-MYPT-1. These findings demonstrate that localized cAMP/PKA signaling is involved in GPER-mediated coronary vasodilation by activating MLCP via inhibition of RhoA pathway.

scholarly journals Cytoprotective effects of albumin, nitrosated or reduced, in cultured rat pulmonary vascular cells

2011 ◽  
Vol 300 (4) ◽  
pp. L526-L533 ◽  
Author(s):  
Hui-Hua Li ◽  
Jing Xu ◽  
Karla J. Wasserloos ◽  
Jin Li ◽  
Yulia Y. Tyurina ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Methyl Ester ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Cellular Respiration ◽  
Dependent Manner ◽  
Protective Effects ◽  
Limited Information ◽  
Concentration Dependent Manner ◽  
Sodium Hydrosulfide

S-nitrosoalbumin (SNO-Alb) has been shown to be an efficacious cytoprotective molecule in acute lung injury, as well as ischemia-reperfusion injury in heart and skeletal muscle. Nonetheless, limited information is available on the cellular mechanism of such protection. Accordingly, we investigated the protective effects of SNO-Alb [ and its denitrosated congener, reduced albumin (SH-Alb) ] on tert-butyl hydroperoxide (tBH)-mediated cytotoxicity in cultured rat pulmonary microvascular endothelial cells (RPMEC), as well as hydrogen sulfide (H2S)-mediated cytotoxicity in rat pulmonary artery smooth muscle cells (RPASMC). We noted that tBH caused a concentration-dependent necrosis in RPMEC, and pretreatment of RPMEC with SNO-Alb dose-dependently decreased the sensitivity of these cells to tBH. A component of SNO-Alb cytoprotection was sensitive to NG-nitro-l-arginine methyl ester and was associated with activation of endothelial nitric oxide synthase (eNOS), phenomena that could be reproduced with pretreatment with SH-Alb. Exogenous H2S caused concentration-dependent apoptosis in RPASMC due to activation of ERK1/2 and p38, as well as downregulation of Bcl-2. Pretreatment with SNO-Alb reduced H2S-mediated apoptosis in a concentration-dependent manner that was associated with SNO-Alb-mediated inhibition of activation of ERK1/2 and p38. Pretreatment with SNO-Alb reduced toxicity of 1 mM sodium hydrosulfide in an NG-nitro-l-arginine methyl ester-sensitive fashion in RPASMC that expressed gp60 and neuronal NOS and was capable of transporting fluorescently labeled SH-Alb. Therefore, SNO-Alb is cytoprotective against models of oxidant-induced necrosis (tBH) and inhibitors of cellular respiration and apoptosis (H2S) in both pulmonary endothelium and smooth muscle, respectively, and a component of such protection can be attributed to a SH-Alb-mediated activation of constitutive NOS.

Peroxide inactivates calcium pumps in pig coronary artery

1992 ◽  
Vol 263 (2) ◽  
pp. H537-H543 ◽  
Author(s):  
A. K. Grover ◽  
S. E. Samson ◽  
V. P. Fomin
Keyword(s):  
Hydrogen Peroxide ◽  
Superoxide Dismutase ◽  
Smooth Muscle ◽  
Plasma Membrane ◽  
Coronary Artery ◽  
Sarcoplasmic Reticulum ◽  
Dual Effect ◽  
Partial Protection ◽  
Calcium Pumps ◽  
Pig Coronary Artery

To study the effects of hydrogen peroxide, pig coronary artery smooth muscle subcellular fractions enriched in plasma membrane (F2) or sarcoplasmic reticulum (F3) were incubated in various concentrations of peroxide and 5 mM azide. ATP-dependent azide-insensitive oxalate-stimulated Ca2+ uptake was determined for F3 and phosphate-stimulated uptake for F2. Only 1.5-5 microM hydrogen peroxide was required for 50% inhibition of the Ca2+ uptake by F3, but the corresponding concentration for F2 was 10-50 microM. This effect was not prevented by superoxide dismutase. Hydrogen peroxide inhibited the Ca(2+)-dependent formation of a 115-kDa acylphosphate band in F3 and 140- and 115-kDa bands in F2. The inhibition of Ca2+ uptake in F3, however, exceeded the inhibition of the acylphosphate formation. Efflux of Ca2+ from F2 and F3 was enhanced by hydrogen peroxide but F3 was more sensitive than F2. We conclude that hydrogen peroxide has dual effect on Ca2+ dynamics in the coronary artery smooth muscle, i.e., it inactivates the Ca2+ pumps and increases membrane permeability to Ca2+. The effect is more pronounced on sarcoplasmic reticulum than on plasma membrane. Intrinsic catalase may, however, provide partial protection against such damage.

H2O2 activates redox- and 4-aminopyridine-sensitive Kv channels in coronary vascular smooth muscle

2007 ◽  
Vol 292 (3) ◽  
pp. H1404-H1411 ◽  
Author(s):  
Paul A. Rogers ◽  
William M. Chilian ◽  
Ian N. Bratz ◽  
Robert M. Bryan ◽  
Gregory M. Dick
Keyword(s):  
Hydrogen Peroxide ◽  
Smooth Muscle ◽  
Coronary Artery ◽  
Alkylating Agent ◽  
Dependent Manner ◽  
Coronary Vasodilation ◽  
Concentration Dependent Manner ◽  
Voltage Gated ◽  
Kv Channels ◽  
Whole Cell Patch Clamp

Previously, we demonstrated that coronary vasodilation in response to hydrogen peroxide (H2O2) is attenuated by 4-aminopyridine (4-AP), an inhibitor of voltage-gated K+ (KV) channels. Using whole cell patch-clamp techniques, we tested the hypothesis that H2O2 increases K+ current in coronary artery smooth muscle cells. H2O2 increased K+ current in a concentration-dependent manner (increases of 14 ± 3 and 43 ± 4% at 0 mV with 1 and 10 mM H2O2, respectively). H2O2 increased a conductance that was half-activated at −18 ± 1 mV and half-inactivated at −36 ± 2 mV. H2O2 increased current amplitude; however, the voltages of half activation and inactivation were not altered. Dithiothreitol, a thiol reductant, reversed the effect of H2O2 on K+ current and significantly shifted the voltage of half-activation to −10 ± 1 mV. N-ethylmaleimide, a thiol-alkylating agent, blocked the effect of H2O2 to increase K+ current. Neither tetraethylammonium (1 mM) nor iberiotoxin (100 nM), antagonists of Ca2+-activated K+ channels, blocked the effect of H2O2 to increase K+ current. In contrast, 3 mM 4-AP completely blocked the effect of H2O2 to increase K+ current. These findings lead us to conclude that H2O2 increases the activity of 4-AP-sensitive KV channels. Furthermore, our data support the idea that 4-AP-sensitive KV channels are redox sensitive and contribute to H2O2-induced coronary vasodilation.

Abstract 172: Thrombopoietin Receptor Agonists Protect Human Cardiac Myocytes from Injury by Activation of Cell Survival Pathways

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
John E Baker ◽  
Jidong Su ◽  
Stacy Koprowski ◽  
Anuradha Dhanasekaran ◽  
Tom P Aufderheide ◽  
...  
Keyword(s):  
Cardiac Myocytes ◽  
Cardiac Myocyte ◽  
Apoptotic Cell ◽  
Ischemia Reperfusion ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Survival Pathways ◽  
Thrombopoietin Receptor ◽  
Reoxygenation Injury ◽  
Hypoxia Reoxygenation

Thrombopoietin confers immediate protection against injury caused by ischemia/reperfusion in the rat heart at a dose that does not increase platelet levels. Eltrombopag is a small molecule agonist of the thrombopoietin receptor; the physiological target of thrombopoietin. Administration of thrombopoietin and eltrombopag result in a dose- and time-dependent increase in platelet counts in patients with thrombocytopenia. However, the ability of eltrombopag and thrombopoietin to immediately protect human cardiac myocytes against injury and the mechanisms underlying myocyte protection are not known. Human cardiac myocytes (7500 cells, n=10/group) were treated with eltrombopag (0.1- 30.0 μM) or thrombopoietin ( 0.1 - 30.0 ng/ml) and then subjected to 5 hours of hypoxia (95% N 2 /5%CO 2 ) and 16 hours of reoxygenation to determine their ability to confer resistance to necrotic and apoptotic myocardial injury . The thrombopoietin receptor (c-Mpl) was detected in unstimulated human cardiac myocytes by western blotting. Eltrombopag and thrombopoietin confer immediate protection to human cardiac myocytes against injury from hypoxia/reoxygenation by decreasing necrotic and apoptotic cell death in a concentration-dependent manner with an optimal concentration of 3 μM for eltrombopag and 1.0 ng/ml for thrombopoietin. The extent of protection conferred to cardiac myocytes with eltrombopag is equivalent to that of thrombopoietin. Eltrombopag and thrombopoietin activate multiple pro-survival pathways; inhibition of JAK-2 (AG-490, 10 μM), p38 MAPK (SB203580, 10 μM), p44/42 MAPK (PD98059, 10 μM), Akt/PI 3 kinase (Wortmannin, 100 nM), and src kinase (PP1, 20 μM) prior to and during hypoxia abolished cardiac myocyte protection by eltrombopag and thrombopoietin. These inhibitors had no effect on hypoxia/reoxygenation injury in myocytes when used alone. Eltrombopag and thrombopoietin may represent important and potent agents for immediately and substantially increasing protection of human cardiac myocytes, and may offer long-lasting benefit through activation of pro-survival pathways during ischemia.

scholarly journals Effect of Paclitaxel+Hirudin on the TLR4-MyD88 Signaling Pathway During Inflammatory Activation of Human Coronary Artery Smooth Muscle Cells and Mechanistic Analysis

2018 ◽  
Vol 50 (4) ◽  
pp. 1301-1317 ◽  
Author(s):  
Hongmei Li ◽  
Xian Wang ◽  
Anlong Xu
Keyword(s):  
Smooth Muscle ◽  
Coronary Artery ◽  
Smooth Muscle Cells ◽  
Muscle Cells ◽  
Dependent Manner ◽  
Human Coronary Artery ◽  
Post Intervention ◽  
Inflammatory Activation ◽  
Myd88 Pathway

Background/Aims: Approximately 10%-20% of patients with acute cardiovascular disease who have received coronary intervention suffer restenosis and high inflammation. The stent compound paclitaxel+hirudin was prepared for the treatment of post-intervention restenosis. This study aimed to explore the anti-inflammatory and anti-restenosis mechanisms of paclitaxel+hirudin with regard to the TLR4/MyD88/NF-κB pathway. Methods: Human coronary artery smooth muscle cells (HCASMCs) at 4-6 generations after in vitro culture were used as a model. Lipopolysaccharide (LPS) was used as an inducer to maximally activate the TLR4/MyD88/NF-κB inflammation pathway. After MyD88 knockdown and selective blocking of MyD88 degradation with epoxomicin, the effects of paclitaxel+hirudin stenting on key sites of the TLR4/MyD88/NF-κB pathway were detected using ELISA, Q-PCR, and western blot analysis. Results: LPS at 1 μg/mL for 48 h was the optimal modeling condition for inflammatory activation of HCASMCs. Paclitaxel+hirudin inhibited the levels of key proteins and the gene expression, except for that of the MyD88 gene, of the TLR4-MyD88 pathway. The trend of the effect of paclitaxel+hirudin on the pathway proteins was similar to that of MyD88 knockdown. After epoxomicin intervention, the inhibitory effects of paclitaxel+hirudin on the key genes and proteins of the TLR4-MyD88 pathway were significantly weakened, which even reached pre-intervention levels. Paclitaxel+hirudin affected the MyD88 protein in a dosage-dependent manner. Conclusion: The paclitaxel+hirudin compound promotes MyD88 degradation in the TLR4/MyD88/NF-κB pathway to reduce the activity of TLR4 and NF-κB p65 and to weaken the LPS-initiated inflammatory reactions of IL-1β, IL-6, and TNF-α.

Sevoflurane Inhibits Guanosine 5′-[γ-thio]triphosphate–stimulated, Rho/Rho-kinase–mediated Contraction of Isolated Rat Aortic Smooth Muscle

2003 ◽  
Vol 99 (3) ◽  
pp. 646-651 ◽  
Author(s):  
Jingui Yu ◽  
Koji Ogawa ◽  
Yasuyuki Tokinaga ◽  
Yoshio Hatano
Keyword(s):  
Smooth Muscle ◽  
Kinase Inhibitor ◽  
Isometric Force ◽  
Rho Kinase ◽  
Force Transducer ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Aortic Smooth Muscle ◽  
Gamma S ◽  
Kinase Pathway

Background The Rho/Rho-kinase signaling pathway plays an important role in mediating Ca2+ sensitization of vascular smooth muscle. The effect of anesthetics on Rho/Rho-kinase-mediated vasoconstriction has not been determined to date. This study is designed to examine the possible inhibitory effects of sevoflurane on the Rho/Rho-kinase pathway by measuring guanosine 5'-[gamma-thio]triphosphate (GTP gamma S)-stimulated contraction and translocation of RhoA (one of the three Rho subtypes) and Rock-2 (one of the two Rho-kinase subtypes) from the cytosol to the membrane in rat aortic smooth muscle. Methods GTP gamma S-induced contraction of rat aortic endothelium-denuded rings was measured using an isometric force transducer, and GTP gamma S-stimulated membrane translocation of RhoA and Rock-2 in smooth muscle cells was detected with Western blotting in the presence and absence of sevoflurane. Results GTP gamma S (10(-4) m) induced a sustained contraction, which was significantly inhibited by the Rho-kinase inhibitor, Y27632 (3 x 10(-6) m). Before treatment with GTP gamma S, RhoA and Rock-2 were detected primarily in the cytosolic fraction. GTP gamma S (10(-4) m) stimulated the translocation of RhoA and Rock-2 from the cytosol to the membrane, which was sustained for more than 60 min. Sevoflurane (1.7, 3.4, and 5.1%) concentration dependently inhibited the GTP gamma S-induced constriction of rat aortic smooth muscle with a reduction of constriction of 52-75% (P < 0.01, n = 8), and attenuated the translocation of RhoA and Rock-2 by 31-66% and 34-78%, respectively (P < 0.05-0.01, respectively; n = 4). Conclusion The current findings show that sevoflurane depresses the GTP gamma S-stimulated contraction and translocation of both Rho and Rho-kinase from the cytosol in a concentration-dependent manner, indicating that sevoflurane is able to inhibit vasoconstriction mediated by the Rho/Rho-kinase pathway in rat aortic smooth muscle.

Abstract 604: Targeting Cx43 Prevents Growth Factor-Induced Phenotypic Change in Pig Coronary Artery Smooth Muscle Cells

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Christos E Chadjichristos ◽  
Sandrine Morel ◽  
Jean-Paul Derouette ◽  
Anne Brisset ◽  
Isabelle Roth ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Coronary Artery ◽  
Growth Factor ◽  
Smooth Muscle Cells ◽  
Muscle Cells ◽  
Phenotypic Change ◽  
Intimal Thickening ◽  
Cx43 Expression ◽  
Junction Protein ◽  
Pig Coronary Artery

Percutaneous coronary intervention (PCI) is commonly used to treat atherosclerotic coronary arteries, but its efficacy is limited by restenosis at the site of the intervention. We reported previously that reducing the expression of the gap junction protein connexin43 (Cx43) in mice restricted neointima formation after acute vascular injury by limiting the inflammatory response as well as the proliferation and migration of smooth muscle cells (SMCs) towards the damaged site. SMC populations isolated from the pig coronary artery exhibit distinct phenotypes: spindle-shaped (S) and rhomboid (R). S-SMCs are predominant in the normal media, whereas R-SMCs are recovered in higher proportion from stent-induced intimal thickening suggesting that they participate in the intimal thickening. Here, we further investigate the relationship between connexin expression and SMC phenotype using the distinct types of pig coronary artery SMCs. We show that Cx40 was highly expressed in normal media of porcine coronary artery in vivo, whereas Cx43 was barely detectable. In contrast, Cx40 was down-regulated and Cx43 was markedly up-regulated in SMCs of stent-induced intimal thickening. In vitro, S-SMCs expressed Cx40 and Cx43. Cx43 expression was increased in R-SMCs and these cells no longer expressed Cx40. When S-SMCs were treated with 10 ng/ml platelet-derived growth factor (PDGF-BB) they acquired a rhomboid phenotype and their migratory activity increased (from 40.3±5.7 to 185.9±27.3 migrating cells; mean±SEM, N=4, P<0.01). These changes were accompanied by an increase in Cx43 and loss of Cx40 expression. Importantly, PDGF-BB-induced phenotypic change of S-SMCs was prevented by reducing Cx43 expression with 100 uM antisense for Cx43. Thus, Cx43 antisense-treated SMCs retained their typical elongated appearance and the expression of some SMC differentiation markers, such as alpha-SM actin, whereas the appearance of S100A4, a typical marker of R-SMCs, was prevented. In conclusion, limiting Cx43 expression in SMCs prevents growth factor-induced changes towards a deleterious phenotype. Our findings suggest that Cx43 might be an additional target for local delivery strategies aimed at reducing restenosis after PCI.

scholarly journals Tat-Cannabinoid Receptor Interacting Protein Reduces Ischemia-Induced Neuronal Damage and Its Possible Relationship with 14-3-3η

Cells ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. 1827 ◽  
Author(s):  
Hyun Jung Kwon ◽  
Duk-Soo Kim ◽  
Woosuk Kim ◽  
Hyo Young Jung ◽  
Yeon Hee Yu ◽  
...  
Keyword(s):  
Cannabinoid Receptor ◽  
Neuronal Damage ◽  
Cell Damage ◽  
Ischemia Reperfusion ◽  
Ischemic Damage ◽  
Dependent Manner ◽  
Ht22 Cells ◽  
Concentration Dependent Manner ◽  
H2o2 Treatment ◽  
Interacting Protein

Cannabinoid receptor-interacting protein 1a (CRIP1a) binds to the C-terminal domain of cannabinoid 1 receptor (CB1R) and regulates CB1R activities. In this study, we made Tat-CRIP1a fusion proteins to enhance CRIP1a penetration into neurons and brain and to evaluate the function of CRIP1a in neuroprotection following oxidative stress in HT22 hippocampal cells and transient forebrain ischemia in gerbils. Purified exogenous Tat-CRIP1a was penetrated into HT22 cells in a time and concentration-dependent manner and prevented H2O2-induced reactive oxygen species formation, DNA fragmentation, and cell damage. Tat-CRIP1a fusion protein also ameliorated the reduction of 14-3-3η expression by H2O2 treatment in HT22 cells. Ischemia–reperfusion damage caused motor hyperactivity in the open field test of gerbils; however, the treatment of Tat-CRIP1a significantly reduced hyperactivity 1 day after ischemia. Four days after ischemia, the administration of Tat-CRIP1a restored the loss of pyramidal neurons and decreased reactive astrocytosis and microgliosis induced by ischemic damage in the hippocampal cornu Ammonis (CA)1 region. Ischemic damage decreased 14-3-3η expression in all hippocampal sub-regions 4 days after ischemia; however, the treatment of Tat-CRIP1 ameliorated the reduction of 14-3-3η expression. These results suggest that Tat-CRIP1a attenuates neuronal damage and hyperactivity induced by ischemic damage, and it restores normal expression levels of 14-3-3η protein in the hippocampus.

Estrogen reduces proliferation and agonist-induced calcium increase in coronary artery smooth muscle cells

1997 ◽  
Vol 272 (4) ◽  
pp. H1996-H2003 ◽  
Author(s):  
R. C. Bhalla ◽  
K. F. Toth ◽  
R. A. Bhatty ◽  
L. P. Thompson ◽  
R. V. Sharma
Keyword(s):  
Cell Proliferation ◽  
Smooth Muscle ◽  
Coronary Artery ◽  
Guinea Pig ◽  
Untreated Control ◽  
Fetal Calf Serum ◽  
Thymidine Incorporation ◽  
Calf Serum ◽  
Causative Role ◽  
Pig Coronary Artery

Epidemiological evidence and estrogen replacement studies suggest that estrogen has a protective effect on the cardiovascular system against coronary artery disease. Vascular smooth muscle (VSM) cell replication has been shown to play a causative role in the pathogenesis of atherosclerosis. Therefore, in this study, we investigated the effect of chronic treatment of cultured guinea pig coronary artery VSM cells with physiological concentrations of 17beta-estradiol (E2) on thymidine incorporation, cell proliferation, and bradykinin-stimulated cytosolic calcium concentration ([Ca2+]i). Bradykinin at physiological concentrations causes contraction of endothelium-denuded guinea pig coronary artery rings in a concentration-dependent manner. VSM cells were first treated with low doses of E2 (10 pg/ml) for 1-2 days followed by treatment for 4-6 days with 50 pg/ml of E2, a concentration similar to that found in pregnancy. Using these protocols, we consistently observed the presence of E2-receptor mRNA in VSM cells by a ribonuclease protection assay. Fetal calf serum-stimulated [3H]thymidine incorporation was significantly reduced (P < 0.05) in E2-treated cells compared with untreated control cells. Similarly, E2 treatment significantly inhibited fetal calf serum-stimulated VSM cell proliferation compared with untreated control cells (P < 0.05). We also tested the hypothesis that E2 treatment attenuates agonist-stimulated [Ca2+]i in VSM cells because acute E2 treatment has been shown to produce relaxation of precontracted isolated coronary artery preparations. E2 treatment of VSM cells resulted in a significant decrease in bradykinin-stimulated [Ca2+]i compared with untreated cells (P < 0.05). In conclusion, our data demonstrate that estrogen at physiological concentrations directly regulates coronary VSM cell function.

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