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Essential role of the Na +-Ca2 + exchanger (NCX) in glutamate-enhanced cell survival in cardiac cells exposed to hypoxia/reoxygenation. Sci Rep 2017; 7:13073. [PMID: 29026150 PMCID: PMC5638850 DOI: 10.1038/s41598-017-13478-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 09/26/2017] [Indexed: 12/22/2022] Open
Abstract
Myocardial ischemia culminates in ATP production impairment, ionic derangement and cell death. The provision of metabolic substrates during reperfusion significantly increases heart tolerance to ischemia by improving mitochondrial performance. Under normoxia, glutamate contributes to myocardial energy balance as substrate for anaplerotic reactions, and we demonstrated that the Na+/Ca2+ exchanger1 (NCX1) provides functional support for both glutamate uptake and use for ATP synthesis. Here we investigated the role of NCX1 in the potential of glutamate to improve energy metabolism and survival of cardiac cells subjected to hypoxia/reoxygenation (H/R). Specifically, in H9c2-NCX1 myoblasts, ATP levels, mitochondrial activities and cell survival were significantly compromised after H/R challenge. Glutamate supplementation at the onset of the reoxygenation phase significantly promoted viability, improved mitochondrial functions and normalized the H/R-induced increase of NCX1 reverse-mode activity. The benefits of glutamate were strikingly lost in H9c2-WT (lacking NCX1 expression), or in H9c2-NCX1 and rat cardiomyocytes treated with either NCX or Excitatory Amino Acid Transporters (EAATs) blockers, suggesting that a functional interplay between these transporters is critically required for glutamate-induced protection. Collectively, these results revealed for the first time the key role of NCX1 for the beneficial effects of glutamate against H/R-induced cell injury.
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2
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Lee EH, Oh JH, Park HJ, Kim DG, Lee JH, Kim CY, Kwon MS, Yoon S. Simultaneous gene expression signature of heart and peripheral blood mononuclear cells in astemizole-treated rats. Arch Toxicol 2010; 84:609-18. [DOI: 10.1007/s00204-010-0529-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2009] [Accepted: 02/22/2010] [Indexed: 01/10/2023]
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Je HD, Sohn UD. Inhibitory effect of genistein on agonist-induced modulation of vascular contractility. Mol Cells 2009; 27:191-8. [PMID: 19277501 DOI: 10.1007/s10059-009-0052-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2008] [Revised: 01/16/2009] [Accepted: 02/13/2009] [Indexed: 11/25/2022] Open
Abstract
The present study was undertaken to determine whether treatment with genistein, the plant-derived estrogen-like compound influences agonist-induced vascular smooth muscle contraction and, if so, to investigate related mechanisms. The measurement of isometric contractions using a computerized data acquisition system was combined with molecular experiments. Genistein completely inhibited KCl-, phorbol ester-, phenylephrine-, fluoride- and thromboxane A(2)-induced contractions. An inactive analogue, daidzein, completely inhibited only fluoride-induced contraction regardless of endothelial function, suggesting some difference between the mechanisms of RhoA/Rho-kinase activators such as fluoride and thromboxane A(2). Furthermore, genistein and daidzein each significantly decreased phosphorylation of MYPT1 at Thr855 had been induced by a thromboxane A(2) mimetic. Interestingly, iberiotoxin, a blocker of large-conductance calcium-activated potassium channels, did not inhibit the relaxation response to genistein or daidzein in denuded aortic rings precontracted with fluoride. In conclusion, genistein or daidzein elicit similar relaxing responses in fluoride-induced contractions, regardless of tyrosine kinase inhibition or endothelial function, and the relaxation caused by genistein or daidzein was not antagonized by large conductance K(Ca)-channel inhibitors in the denuded muscle. This suggests that the RhoA/Rho-kinase pathway rather than K(+)-channels are involved in the genistein-induced vasodilation. In addition, based on molecular and physiological results, only one vasoconstrictor fluoride seems to be a full RhoA/Rho-kinase activator; the others are partial activators.
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Affiliation(s)
- Hyun Dong Je
- Department of Pharmacology, College of Pharmacy, Catholic University of Daegu, Gyeongsan, 712-702, Korea
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4
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Yang Y, Qiao J, Wang H, Gao M, Ou D, Zhang J, Sun M, Yang X, Zhang X, Guo Y. Calcium antagonist verapamil prevented pulmonary arterial hypertension in broilers with ascites by arresting pulmonary vascular remodeling. Eur J Pharmacol 2007; 561:137-43. [PMID: 17320074 DOI: 10.1016/j.ejphar.2007.01.036] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2006] [Revised: 01/09/2007] [Accepted: 01/11/2007] [Indexed: 10/23/2022]
Abstract
Calcium signaling has been reported to be involved in the pathogenesis of hypertension. Verapamil, one of the calcium antagonists, is used to characterize the role of calcium signaling in the development of pulmonary arterial hypertension syndrome in broilers. The suppression effect of verapamil on pulmonary arterial hypertension and pulmonary vascular remodeling was examined in broilers, from the age of 16 days to 43 days. Our results showed that oral administration of lower dose of verapamil (5 mg/kg body weight every 12 h) prevented the mean pulmonary arterial pressure, the ascites heart index and the erythrocyte packed cell volume of birds at low temperature from increasing, the heart rate from decreasing, and pulmonary arteriole median from thickening, and no pulmonary arteriole remodeling in broilers treated with the two doses of verapamil at low temperature was observed. Our results indicated that calcium signaling was involved in the development of broilers' pulmonary arterial hypertension, which leads to the development of ascites, and we suggest that verapamil may be used as a preventive agent to reduce the occurrence and development of pulmonary arterial hypertension in broilers.
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Affiliation(s)
- Ying Yang
- State Key Lab of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Beijing, 100094, P. R. China
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5
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King N, Lin H, McGivan JD, Suleiman MS. Expression and activity of the glutamate transporter EAAT2 in cardiac hypertrophy: implications for ischaemia reperfusion injury. Pflugers Arch 2006; 452:674-82. [PMID: 16718509 DOI: 10.1007/s00424-006-0096-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2006] [Revised: 04/05/2006] [Accepted: 04/19/2006] [Indexed: 11/26/2022]
Abstract
The expression and activity of the glutamate transporter, excitatory amino acid transporter 2 (EAAT2), in cardiac hypertrophy were investigated with respect to glutamate's potential as a cardioprotective agent. Sarcolemmal vesicles (SV) isolated from hypertrophic hearts of male spontaneously hypertensive rats (SHR) or normotrophic hearts from age-matched male Wistar Kyoto rats (WKY) were used to measure the relative level of EAAT2 expression by Western blotting and the initial rate of 0-0.3 mM L-[(14)C]glutamate uptake. The effects of 20-min global normothermic ischaemia +/-0.5 mM glutamate on cardiac function were measured in isolated working SHR/WKY hearts. In a separate series of hearts, glutamate, lactate and ATP levels were measured. Both the level of EAAT2 expression and the V (max) for sodium-dependent L-[(14)C]glutamate uptake were significantly greater in SHR SV compared to WKY SV. The reperfusion cardiac output (CO) of SHR hearts was significantly worse than that of the WKY hearts (24.3+/-2.2 ml/min vs 39.8+/-3.3 ml/min, n=7/9+/-SE, p<0.01). The addition of 0.5 mM L-glutamate improved the SHR reperfusion CO to 45.2+/-5 ml/min, (n=6+/-SE, p<0.01) but had no effect on WKYs (46.2+/-3.8 ml/min, n=6+/-SE). SHR with 0.5 mM L-glutamate had higher glutamate levels at the start of ischaemia, plus higher glutamate and ATP levels at the end of ischaemia compared to any other group. These results suggest that increased glutamate transporter expression and activity in the SHR hearts helped facilitate glutamate entry into the SHR cardiomyocytes leading to improved myocardial metabolism during ischaemia and better functional recovery on reperfusion.
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Affiliation(s)
- Nicola King
- Bristol Heart Institute, Department of Clinical Science at South Bristol, University of Bristol, Bristol Royal Infirmary, Bristol BS2 8HW, UK.
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6
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Hsu MF, Chen YS, Huang LJ, Tsao LT, Kuo SC, Wang JP. GEA3162, a nitric oxide-releasing agent, activates non-store-operated Ca2+ entry and inhibits store-operated Ca2+ entry pathways in neutrophils through thiol oxidation. Eur J Pharmacol 2006; 535:43-52. [PMID: 16540105 DOI: 10.1016/j.ejphar.2006.02.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2005] [Revised: 02/03/2006] [Accepted: 02/07/2006] [Indexed: 10/24/2022]
Abstract
We demonstrated that 5-amino-3-(3,4-dichlorophenyl)1,2,3,4-oxatriazolium (GEA3162), a nitric oxide (NO)-releasing agent, stimulated [Ca2+]i rise in rat neutrophils. This Ca2+ response was prevented by the thiol reducing agents, 2-mercaptoethanol, N-acetyl-L-cysteine, dithiothreitol, 2,3-dimercaptopropane-1-sulfonic acid (DMPS) and tris-(2-carboxyethyl)phosphine (TCEP), but slightly reduced by the antioxidant, 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox). GEA3162 also increased the formation of cellular reactive oxygen intermediates and decreased the cellular content of low molecular thiols. These responses were greatly reduced by Trolox, dithiothreitol and N-acetyl-L-cysteine. GEA3162 stimulated the protein tyrosine phosphorylation in neutrophils. The [Ca2+]i rise caused by formyl-Met-Leu-Phe (fMLP) and cyclopiazonic acid (CPA) was suppressed by GEA3162. TCEP prevented the inhibition of fMLP-induced [Ca2+]i rise by GEA3162. In the absence of external Ca2+, GEA3162 inhibited the CPA-induced [Ca2+]i rise, whereas it only slightly affected the fMLP-induced mobilization of the Ca2+ store. Application of GEA3162 after the stimulation with fMLP or CPA suppressed the robust Ca2+ entry followed by the readdition of Ca2+ into medium. Moreover, the Ca2+ entry was more susceptible to inhibition by treatment with GEA3162 prior to than after the fMLP stimulation. GEA3162 had no effect on the mitochondrial membrane potential. GEA3162 induced actin reorganization and condensed filament network at the cell periphery. These results indicate that GEA3162 exerted both the stimulation of Ca2+ entry and the inhibition of the store-operated Ca2+ entry in rat neutrophils. The dual effects of GEA3162 on the regulation of the external Ca2+ entry are mainly through the thiol modification of target protein(s) residing on the outside of the plasma membrane.
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Affiliation(s)
- Mei-Feng Hsu
- Department of Biochemistry, School of Medicine, China Medical University, Taichung, Taiwan, Republic of China
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7
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Lee MYK, Leung SWS, Vanhoutte PM, Man RYK. Genistein reduces agonist-induced contractions of porcine coronary arterial smooth muscle in a cyclic AMP-dependent manner. Eur J Pharmacol 2005; 503:165-72. [PMID: 15496311 DOI: 10.1016/j.ejphar.2004.09.028] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2004] [Revised: 09/09/2004] [Accepted: 09/14/2004] [Indexed: 11/18/2022]
Abstract
Low concentrations of genistein enhance the vasodilatation induced by endothelium-independent vasodilators. The present study examined whether or not low concentrations of genistein modulate contractions in isolated porcine coronary arteries. The role of second messengers in the response to genistein was also assessed. Arterial rings were studied in organ baths and contracted with KCl, U-46619 (9,11-dideoxy-9alpha, 11alpha-methanoepoxy prostaglandin F2alpha), 5-hydroxytryptamine (5-HT) or endothelin-1 in the absence or presence of genistein (< or =3 microM). Genistein significantly reduced agonist-induced but not KCl-induced contraction. Inhibition of endothelial nitric oxide synthase and disruption of endothelial function by Triton-X100 did not affect the modulation of contraction by genistein. The genistein-induced attenuation of contraction could be mimicked by both cAMP and cGMP analogs. However, only the cAMP-dependent protein kinase inhibitor, Rp-8-Br-cAMPS, abolished the effect of genistein. These results suggest that genistein reduces agonist-induced contraction by an endothelium-independent manner. This action is mediated via the cAMP-dependent signal transduction pathway.
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Affiliation(s)
- Mary Y K Lee
- Department of Pharmacology, 2/F Laboratory Block, Faculty of Medicine Building, The University of Hong Kong, 21 Sassoon Road, Hongkong SAR, China
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Kugler P. Expression of glutamate transporters in rat cardiomyocytes and their localization in the T-tubular system. J Histochem Cytochem 2004; 52:1385-92. [PMID: 15385585 DOI: 10.1177/002215540405201015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Glutamate and aspartate play important roles in the intermediary metabolism of the myocardium and have been shown to improve cardiac recovery after hypoxia or ischemia. Limited data are available about the expression of glutamate transporters that are involved in the uptake of glutamate and aspartate in cardiomyocytes. In this study, non-radioactive in situ hybridization (ISH) using complementary RNA probes was applied to detect the glutamate transporters GLT1 variant (GLT1v) and EAAC1 mRNA in rat cardiomyocytes. The transporter proteins were demonstrated by Western blotting and immunocytochemistry using affinity-purified antibodies against transporter peptides. ISH and immunocytochemistry showed that both glutamate transporters are coexpressed in cardiomyocytes. The ISH labeling indicates the distribution of transporter mRNA throughout the cytoplasm of cardiomyocytes. GLT1v and EAAC1 proteins, which showed in Western blots a molecular mass of approximately 60 kD, are strongly enriched and colocalized in the transverse (T)-tubular system of cardiomyocytes. These results may indicate that glutamate/aspartate uptake into cardiomyocytes could be mediated by the high-affinity transporters GLT1v and EAAC1. A high efficiency of glutamate/aspartate transport into cardiomyocytes could be achieved by their localization in the T-tubular system, which consists of tubular invaginations of the sarcolemma extending deep into the cell.
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Affiliation(s)
- Peter Kugler
- Institute of Anatomy and Cell Biology, University of Würzburg, Koellikerstr. 6, D-97070 Würzburg, Germany.
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Wang JP, Chang LC, Kuan YH, Tsao LT, Huang LJ, Kuo SC. 2-Benzyloxybenzaldehyde inhibits formyl peptide-stimulated increase in intracellular Ca2+ in neutrophils mainly by blocking Ca2+ entry. Naunyn Schmiedebergs Arch Pharmacol 2004; 370:353-60. [PMID: 15526104 DOI: 10.1007/s00210-004-0993-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2004] [Accepted: 09/24/2004] [Indexed: 10/26/2022]
Abstract
2-Benzyloxybenzaldehyde (CCY1a) inhibited the formyl-Met-Leu-Phe (fMLP)-induced elevation of cytosolic [Ca(2+)]() ([Ca(2+)](i)) in rat neutrophils. The late plateau phase, but not the initial Ca(2+) spike, of the fMLP-induced [Ca(2+)](i) change was inhibited by CCY1a. In the absence of external Ca(2+), CCY1a had no appreciable effect on either the fMLP- or cyclopiazonic acid (CPA)-induced [Ca(2+)](i) elevation. CCY1a failed to inhibit [Ca(2+)](i) changes induced by N-ethylmaleimide, GEA3162, ionomycin or sphingosine, but slightly inhibited the Ca(2+) signals elicited by ATP or interleukin-8 (IL-8). In a classical Ca(2+) readdition protocol, addition of CCY1a after cell activation strongly inhibited the [Ca(2+)](i) response to fMLP, whilst that to CPA was only slightly reduced. CCY1a nearly abrogated the fMLP-stimulated Mn(2+) influx but was less effective on the CPA-induced response. CCY1a attenuated the levels of tyrosine-phosphorylated bands in the 70-85 kDa molecular mass range. CCY1a had no effect on the basal [Ca(2+)](i) level, the pharmacologically isolated plasma membrane Ca(2+)-ATPase activity or on the mitochondrial membrane potential. Thus, CCY1a blocks fMLP-induced Ca(2+) entry into neutrophils probably by blocking the relevant Ca(2+) channel directly or, alternatively, indirectly through the attenuation of tyrosine phosphorylation of some cellular proteins.
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Affiliation(s)
- Jih-Pyang Wang
- Department of Education and Research, Taichung Veterans General Hospital, Taichung, Taiwan; Graduate Institute of Pharmaceutical Chemistry, China Medical University, Taichung, Taiwan, ROC.
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Werry TD, Wilkinson GF, Willars GB. Mechanisms of cross-talk between G-protein-coupled receptors resulting in enhanced release of intracellular Ca2+. Biochem J 2003; 374:281-96. [PMID: 12790797 PMCID: PMC1223610 DOI: 10.1042/bj20030312] [Citation(s) in RCA: 145] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2003] [Revised: 06/03/2003] [Accepted: 06/05/2003] [Indexed: 12/21/2022]
Abstract
Alteration in [Ca(2+)](i) (the intracellular concentration of Ca(2+)) is a key regulator of many cellular processes. To allow precise regulation of [Ca(2+)](i) and a diversity of signalling by this ion, cells possess many mechanisms by which they are able to control [Ca(2+)](i) both globally and at the subcellular level. Among these are many members of the superfamily of GPCRs (G-protein-coupled receptors), which are characterized by the presence of seven transmembrane domains. Typically, those receptors able to activate PLC (phospholipase C) enzymes cause release of Ca(2+) from intracellular stores and influence Ca(2+) entry across the plasma membrane. It has been well documented that Ca(2+) signalling by one type of GPCR can be influenced by stimulation of a different type of GPCR. Indeed, many studies have demonstrated heterologous desensitization between two different PLC-coupled GPCRs. This is not surprising, given our current understanding of negative-feedback regulation and the likely shared components of the signalling pathway. However, there are also many documented examples of interactions between GPCRs, often coupling preferentially to different signalling pathways, which result in a potentiation of Ca(2+) signalling. Such interactions have important implications for both the control of cell function and the interpretation of in vitro cell-based assays. However, there is currently no single mechanism that adequately accounts for all examples of this type of cross-talk. Indeed, many studies either have not addressed this issue or have been unable to determine the mechanism(s) involved. This review seeks to explore a range of possible mechanisms to convey their potential diversity and to provide a basis for further experimental investigation.
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Affiliation(s)
- Tim D Werry
- Department of Cell Physiology and Pharmacology, Medical Sciences Building, University of Leicester, UK
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Adegunloye BJ, Su X, Camper EV, Moreland RS. Sensitivity of rabbit aorta and mesenteric artery to norepinephrine: role of tyrosine kinases. Eur J Pharmacol 2003; 476:201-9. [PMID: 12969767 DOI: 10.1016/s0014-2999(03)02183-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We tested the hypothesis that the differential sensitivity of rabbit aorta and mesenteric artery to norepinephrine is due to tyrosine kinase activity. The EC50 of aorta to norepinephrine was 6.5 times more sensitive than that in mesenteric artery. Basal myosin light chain phosphorylation was significantly greater in aorta as compared to mesenteric artery. Vanadate increased norepinephrine sensitivity significantly more in mesenteric artery than aorta, whereas genistein had the opposite effect. Basal phosphotyrosine levels were significantly higher in aorta than in mesenteric artery, the percentage increase in total tyrosine phosphorylated protein was significantly higher in mesenteric artery. These results suggest that the higher basal phosphotyrosine levels in the aorta may be responsible for the higher basal level of myosin light chain phosphorylation and this may be the basis for the higher sensitivity of the aorta to norepinephrine when compared with the mesenteric artery.
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MESH Headings
- Animals
- Aorta, Thoracic/drug effects
- Aorta, Thoracic/metabolism
- Aorta, Thoracic/physiology
- Blotting, Western
- Electrophoresis, Polyacrylamide Gel
- Genistein/pharmacology
- In Vitro Techniques
- Isometric Contraction/drug effects
- Male
- Mesenteric Arteries/drug effects
- Mesenteric Arteries/metabolism
- Mesenteric Arteries/physiology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Muscle, Smooth, Vascular/physiology
- Myosin Light Chains/metabolism
- Norepinephrine/pharmacology
- Phosphorylation
- Phosphotyrosine/metabolism
- Protein-Tyrosine Kinases/antagonists & inhibitors
- Protein-Tyrosine Kinases/metabolism
- Rabbits
- Receptors, Adrenergic/metabolism
- Time Factors
- Vasoconstrictor Agents/pharmacology
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Affiliation(s)
- Banji J Adegunloye
- Department of Pharmacology and Physiology, Drexel University College of Medicine, 245 N 15th Street, MS# 488, Philadelphia, PA 19102, USA
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12
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Lee DL, Wamhoff BR, Katwa LC, Reddy HK, Voelker DJ, Dixon JL, Sturek M. Increased endothelin-induced Ca2+ signaling, tyrosine phosphorylation, and coronary artery disease in diabetic dyslipidemic Swine are prevented by atorvastatin. J Pharmacol Exp Ther 2003; 306:132-40. [PMID: 12663685 DOI: 10.1124/jpet.103.049577] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Endothelin-1 (ET-1) signaling mechanisms have been implicated in the pathogenesis of excess coronary artery disease in diabetic dyslipidemia. We hypothesized that in diabetic dyslipidemia ET-1-induced coronary smooth muscle calcium (Ca2+m) and tyrosine phosphorylation would be increased, and the lipid lowering agent, atorvastatin, would inhibit these increases. Male Yucatan miniature swine groups were treated for 20 weeks: normal low-fat fed control, high-fat/cholesterol fed (hyperlipidemic), hyperlipidemic made diabetic with alloxan (diabetic dyslipidemic), and diabetic dyslipidemic treated with atorvastatin (atorvastatin-treated). Blood glucose values were 5-fold greater in diabetic dyslipidemic and atorvastatin-treated versus control and hyperlipidemic. Total and low-density lipoprotein (LDL) plasma cholesterol in hyperlipidemic, diabetic dyslipidemic, and atorvastatin-treated were approximately 5-fold greater than control. Intravascular ultrasound detectable coronary disease and hypertriglyceridemia were only observed in diabetic dyslipidemic and were abolished by atorvastatin. In freshly isolated cells, the Ca2+m response to ET-1 in diabetic dyslipidemic was greater than in control, hyperlipidemic, and atorvastatin-treated groups. Selective ET-1 receptor antagonists showed in the control group that the ETB subtype inhibits ETA regulation of Ca2+m. There was almost a complete switch of receptor subtype regulation of Ca2+m from largely ETA in control to an increased inhibitory interaction between ETA and ETB in hyperlipidemic and diabetic dyslipidemic groups, such that neither ETA nor ETB antagonist alone could block the ET-1-induced Ca2+m response. The inhibitory interaction was attenuated in the atorvastatin-treated group. In single cells, basal and ET-1-induced tyrosine phosphorylation in diabetic dyslipidemic were more than 3- and 6-fold greater, respectively, than in control, hyperlipidemic, and atorvastatin-treated. Attenuation by atorvastatin of coronary disease and ET-1-induced Ca2+m and tyrosine phosphorylation signaling with no change in cholesterol provides strong evidence for direct actions of atorvastatin and/or triglycerides on the vascular wall.
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Affiliation(s)
- D L Lee
- Department of Medical Pharmacology and Physiology, MA415 Medical Sciences Building, School of Medicine, University of Missouri, Columbia, MO 65212, USA
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Shin CY, Lee YP, Lee TS, Je HD, Kim DS, Sohn UD. The signal transduction of endothelin-1-induced circular smooth muscle cell contraction in cat esophagus. J Pharmacol Exp Ther 2002; 302:924-34. [PMID: 12183648 DOI: 10.1124/jpet.302.3.924] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
It has been known that endothelin-1 (ET-1) exerts important actions in gastrointestinal smooth muscle motility, but its precise mechanism remains unsolved. We investigated the intracellular mechanism of ET-1-induced circular smooth muscle cell contraction in cat esophagus. ET-1 produced contraction of smooth muscle cells isolated by enzymatic digestion. The contraction in response to ET-1 was concentration-dependent. Pertussis toxin (PTX) blocked contraction induced by ET-1 in intact cells. To identify the specific G protein involved in the contraction, muscle cells were permeabilized with saponin. The G(i3) or G(beta) protein antibody inhibited the contraction. Neomycin phospholipase C (PLC) inhibitor inhibited the contraction, but 7,7-dimethyleicosadienoic acid (phospholipase A(2) inhibitor) and p-chloromercuribenzoic acid (phospholipase D inhibitor) had no effects. Incubation of permeabilized cells with PLC-beta(3) isozyme antibody inhibited the contraction. 1-(5-Isoquinolinesulfonyl)-2-methylpiperazine, chelerythrine [protein kinase C (PKC) inhibitor], or genistein (protein tyrosine kinase inhibitor) inhibited the contraction, but not by diacylglycerol (DAG) kinase inhibitor, R59949. To test whether the contraction may be PKC isozyme-specific, we examined the effect of PKC isozymes antibodies on the contraction. PKC-epsilon antibody inhibited the contraction. To characterize further the specific PKC isozymes that mediate the contraction, we used, as an inhibitor, N-myristoylated peptides (myr-PKC) derived from the pseudosubstrate sequences of PKC-alphabetagamma, -alpha, -delta, or -epsilon. myr-PKC-epsilon inhibited the contraction, confirming that PKC-epsilon isozyme is involved in the contraction. To examine whether mitogen-activated protein kinases (MAPKs) mediate the contraction, specific MAPK inhibitors [MAPK kinase inhibitor, PD98059, (2'-amino-3'-methoxy-flavone), and p38 MAPK inhibitor, SB202190 (4-4-fluorophenyl) 2-(4-hydroxyphenyl)-5-(4-pyridyl)1H-imidazole)] were used. PD98059 or SB202190 blocked the contraction. ET-1 increased the intensity of the detection bands identified by immunological methods as MAPK monoclonal p44/p42 peptides. PD98059 decreased the intensity of the detection bands compared with ET-1. In conclusion, ET-1-induced contraction in cat esophageal circular muscle cells depends on PTX-sensitive G(i3) protein and PLC-beta(3) isozyme, resulting in the activation of PKC-epsilon- or protein-tyrosine kinase-dependent pathway, subsequently mediating the activation of p44/p42 MAPK or p38 MAPK pathway.
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Affiliation(s)
- Chang Yell Shin
- Department of Pharmacology, College of Pharmacy, Chung Ang University, Seoul 156-756, Republic of Korea
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14
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Lee DL, Sturek M. Endothelin-induced myoplasmic Ca2+ responses and tyrosine phosphorylation in coronary smooth muscle. J Cardiovasc Pharmacol 2002; 40:18-27. [PMID: 12072573 DOI: 10.1097/00005344-200207000-00003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
This study investigated the role of tyrosine phosphorylation and source of Ca2+ in prolonged endothelin-1 (ET-1)-induced potentiation of myoplasmic free Ca2+ ([Ca2+]m) responses to depolarization in coronary smooth muscle cells. Fura-2 microfluorometry showed typical increases in [Ca2+]m in response to 80 mM K+ (80K) and 0.01 microM endothelin. After washout of ET-1 80K-induced [Ca2+]m increases were augmented (potentiated) 31%. Time to peak [Ca2+]m response to 80K was less after ET-1 exposure than before. ET-1 potentiation of 80K-induced [Ca2+]m responses by decreased sarcoplasmic reticulum (SR) buffering of [Ca2+]m or Ca2+-induced Ca2+ release was ruled out by lack of potentiation by 5 mM caffeine and 1 microM thapsigargin. Diltiazem abolished potentiation, providing evidence for Ca2+ influx through voltage-gated Ca2+ channels (VGCC). Genistein (30 microM) and methyl 2,5-dihydroxycinnamate (1 microM, MDHC) abolished potentiation of Ca2+ influx. Single cell phosphotyrosine measured directly by immunofluorescence was increased 95% in cells treated with ET-1 compared to control, genistein, and MDHC treated cells. ET-1 increased tyrosine phosphorylation of an 80-85 kDa protein, but not the 240 kDa alpha1C subunit of the VGCC. Tyrosine phosphorylation of proteins other than VGCC is necessary for prolonged potentiation by ET-1 of depolarization-induced Ca2+ influx.
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Affiliation(s)
- Dexter L Lee
- Department of Physiology, School of Medicine, Dalton Cardiovascular Research Center, and Diabetes and Cardiovascular Biology Program, University of Missouri, Columbia, Missouri 65212, USA
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15
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Ishihata A, Tasaki K, Katano Y. Involvement of p44/42 mitogen-activated protein kinases in regulating angiotensin II- and endothelin-1-induced contraction of rat thoracic aorta. Eur J Pharmacol 2002; 445:247-56. [PMID: 12079690 DOI: 10.1016/s0014-2999(02)01790-9] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
In order to elucidate the signal transduction pathway of vascular smooth muscle contraction induced by the activation of receptors for angiotensin II and endothelin-1, we examined whether tyrosine kinases and mitogen-activated protein (MAP) kinases are involved in the development of force of contraction in the rat aorta. Isolated aortic smooth muscles without endothelium were incubated in a modified Krebs-Henseleit solution and stimulated with angiotensin II (100 nM) or endothelin-1 (10 nM). A tyrosine kinase inhibitor genistein (10 microM) reduced the angiotensin II- and endothelin-1-induced aortic contraction, while 10 microM of daidzein (an inactive analogue of genistein) did not. The K(+) depolarization-induced contraction was not attenuated by 10 microM of genistein. Selective inhibitors of MAP kinase/extracellular signal-regulated kinase (Erk) kinase (MEK) such as PD98059 [2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one] and U0126 [1,4-diamino-2,3-dicyano-1,4-bis(2-aminophenylthio)butadiene] inhibited the angiotensin II- and endothelin-1-induced vasocontraction. The p44/42 MAP kinases were phosphorylated in cultured aortic smooth muscle cells and in physiologically contracted aortic vessels stimulated with angiotensin II and endothelin-1 for 5 min. The angiotensin II- and endothelin-1-induced phosphorylations of p44/42 MAP kinases were inhibited by PD98059 as well as U0126 in the intact aorta. These results suggest that the activation of genistein-sensitive tyrosine kinases and p44/42 MAP kinases is involved in the angiotensin II- and endothelin-1-induced rat aortic contraction.
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Affiliation(s)
- Akira Ishihata
- Department of Physiology I, Yamagata University School of Medicine, 2-2-2, Iida-Nishi, Japan.
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16
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Tolloczko B, Turkewitsch P, Choudry S, Bisotto S, Fixman ED, Martin JG. Src modulates serotonin-induced calcium signaling by regulating phosphatidylinositol 4,5-bisphosphate. Am J Physiol Lung Cell Mol Physiol 2002; 282:L1305-13. [PMID: 12003787 DOI: 10.1152/ajplung.00304.2001] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We tested the hypothesis that, in airway smooth muscle cells, stimulation of G-protein-coupled receptors by contractile agonists activates Src kinase and that this kinase modulates cell contractility and Ca(2+) signaling by affecting the levels of the phospholipase C substrate phosphatidylinositol 4,5-bisphosphate (PIP(2)). Stimulation of cultured rat tracheal smooth muscle cells with serotonin (5-HT) induced an increase in Src activity, Ca(2+) mobilization, and contraction (decrease in cell area). 5-HT-evoked cell contraction was reduced by a specific inhibitor of Src family kinases, 4-amino-5(4-methylphenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine (PP1). Peak Ca(2+) responses to 5-HT were attenuated by PP1 and an anti-Src-blocking antibody and augmented by expression of constitutively activated Y529F Src. Sustained phases of Ca(2+) responses to 5-HT and Ca(2+) influx resulting from emptying of Ca(2+) stores in the endoplasmic reticulum by thapsigargin were also decreased after PP1 treatment. PP1 significantly reduced the turnover of inositol phosphates produced on 5-HT stimulation and the amount of PIP(2) in the Triton X-100-insoluble lipid fraction. Overall, these data demonstrate that, in rat tracheal smooth muscle cells, Src kinase modulates 5-HT-evoked cell contractility and Ca(2+) signaling by regulating PIP(2) levels and Ca(2+) influx.
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Affiliation(s)
- Barbara Tolloczko
- Seymour Heisler Laboratory of Montreal Chest Institute Research Centre and Meakins Christie Laboratories, Department of Medicine, McGill University, Montreal, Quebec, Canada H2X 2P2
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17
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Fang LH, Kwon SC, Zhang YH, Ahn HY. Tyrosine kinase participates in vasoconstriction through a Ca(2+)- and myosin light chain phosphorylation-independent pathway. FEBS Lett 2002; 512:282-6. [PMID: 11852096 DOI: 10.1016/s0014-5793(02)02235-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
This study was undertaken to determine the role of tyrosine kinase on intracellular Ca(2+) ([Ca(2+)](i)), myosin light chain (MLC) phosphorylation, and contraction caused by norepinephrine (NE) in rat aorta. NE induced a sustained contraction with an increase of [Ca(2+)](i). On the other hand, NE increased the phosphorylation of the 20 kDa MLC transiently. Pretreatment with genistein and tyrophostin 25, tyrosine kinase inhibitors, significantly inhibited NE-induced contraction, but did not affect the increase of [Ca(2+)](i) and MLC phosphorylation. These results suggest that tyrosine kinase may regulate the NE-mediated contraction without altering [Ca(2+)](i) and MLC phosphorylation in rat aorta.
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Affiliation(s)
- Lian Hua Fang
- Department of Pharmacology, College of Medicine, Chungbuk National University, 361-763, Cheongju, South Korea
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18
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Hsu L, Rockenstein E, Mallory M, Hashimoto M, Masliah E. Altered expression of glutamate transporters under hypoxic conditions in vitro. J Neurosci Res 2001; 64:193-202. [PMID: 11288147 DOI: 10.1002/jnr.1065] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Regulation of extracellular excitotoxins by glial and neuronal glutamate transporters is critical to maintain synaptic terminal integrity. Factors interfering with the normal functioning of these transporters might be involved in neurodegeneration. Among them, recent studies have shown that hypoxia alters glutamate transporter function; however, it is unclear if hypoxia has an effect on the expression of glutamate transporters and which intracellular signaling pathways are involved. The C6 rat glial and GT1--7 mouse neuronal cell lines were exposed to hypoxic conditions (5% CO(2), 95% N(2)) and levels of glutamate transporter mRNA were determined by ribonuclease protection assay. After 21 hr, there was a 100% increase in levels of rat excitatory amino acid transporter 3 (EAAT3) mRNA in C6 cells and a 600% increase in levels of murine EAAT2 mRNA in GT1--7 cells. There was a similar increase in mRNA levels after hypoxia in C6 cells transfected with human EAAT2, whereas reoxygenation normalized the expression levels of glutamate transporters. Although the expression of EAATs was associated with increased immunoreactivity by Western blot, functioning of the transporters was decreased as evidenced by D-aspartate uptake. Finally, although the protein kinase C stimulator phorbol-12-myristate-13-acetate enhanced EAAT2 mRNA levels after hypoxia, protein kinase C inhibitor bisindolylmaleimide I had the opposite effect. Taken together, this study suggests that the hypoxia is capable of upregulating levels of EAATs via a protein kinase C-dependent compensatory mechanism. This increased expression is not sufficient to overcome the decreased functioning of the EAATs associated with decreased ATP production and mitochondrial dysfunction.
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Affiliation(s)
- L Hsu
- Department of Neurosciences, University of California, San Diego, La Jolla, 92093-0624, USA
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19
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Tolloczko B, Tao FC, Zacour ME, Martin JG. Tyrosine kinase-dependent calcium signaling in airway smooth muscle cells. Am J Physiol Lung Cell Mol Physiol 2000; 278:L1138-45. [PMID: 10835318 DOI: 10.1152/ajplung.2000.278.6.l1138] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Contractile agonists may stimulate mitogenic responses in airway smooth muscle by mechanisms that involve tyrosine kinases. The role of contractile agonist-evoked activation of tyrosine kinases in contractile signaling is not clear. We addressed this issue using cultured rat airway smooth muscle cells. In these cells, serotonin (5-HT, 1 microM) caused contraction (quantitated by a decrease in cell area), which was blocked by the tyrosine kinase inhibitor genistein (40 microM). Genistein and tyrphostin 23 (40 and 10 microM, respectively) significantly decreased 5-HT-evoked peak Ca(2+) responses, and the effect of genistein could be observed in the absence of extracellular Ca(2+). The specific inhibitor of mitogen-activated protein kinase kinase PD-98059 (30 microM) had no significant effect on peak Ca(2+) levels. Western analysis of cell extracts revealed that 5-HT caused a significant increase in tyrosine phosphorylation of proteins with molecular masses of approximately 70 kDa within 10 s of stimulation but no measurable tyrosine phosphorylation of the gamma isoform of phospholipase C (PLC-gamma). Tyrosine phosphorylation was inhibited by genistein. Furthermore, genistein (40 microM) significantly attenuated 5-HT-induced inositol phosphate production. We conclude that in airway smooth muscle contractile agonists acting on G protein-coupled receptors may activate tyrosine kinase(s), which in turn modulate calcium signaling by affecting, directly or indirectly, PLC-beta activity. It is unlikely that PLC-gamma or the mitogen-activated protein kinase pathway is involved in Ca(2+) signaling to 5-HT.
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Affiliation(s)
- B Tolloczko
- Seymour Heisler Laboratory of the Montreal Chest Institute Research Centre and Meakins-Christie Laboratories, Department of Medicine, McGill University, Montreal, Quebec, Canada
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20
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Masumoto N, Tanabe Y, Saito M, Nakayama K. Attenuation of pressure-induced myogenic contraction and tyrosine phosphorylation by fasudil, a cerebral vasodilator, in rat cerebral artery. Br J Pharmacol 2000; 130:219-30. [PMID: 10807658 PMCID: PMC1572061 DOI: 10.1038/sj.bjp.0703292] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The mechanism by which fasudil inhibits pressure-induced myogenic contraction was studied with regard to tyrosine phosphorylation in rat cerebral artery. Intracellular Ca(2+) concentration ([Ca(2+)](i)) and vessel diameter were simultaneously measured. Total tyrosine phosphorylation level and phosphorylation of tyrosine 419 on pp60(src) required for its full catalytic activity were immunocytochemically detected in situ. Fasudil (1 - 100 microM) partially suppressed the increase in [Ca(2+)](i), and totally attenuated contraction elicited by pressurization from 10 to 60 mmHg. Furthermore, fasudil (100 microM) significantly attenuated tyrosine phosphorylation and the activity of pp60(src) augmented in situ by pressure. Herbimycin A (1 - 100 nM) and genistein (3 - 30 microM), tyrosine kinase inhibitors, effectively attenuated the pressure-induced increase in [Ca(2+)](i), contraction, tyrosine phosphorylation, and activation of pp60(src). Both fasudil and herbimycin A directly inhibited the pp60(src) activity in a cell free system. Orthovanadate (100 microM), a tyrosine phosphatase inhibitor, significantly potentiated the pressure-induced increase in [Ca(2+)](i) and contraction. Nicardipine (100 nM), a Ca(2+) antagonist, completely inhibited pressure-induced increase in [Ca(2+)](i) and contraction, but affected neither tyrosine phosphorylation nor activity of pp60(src) in the pressurized arteries. Arginine-glycine-aspartic acid-serine peptide (1 - 100 microM) concentration-dependently reduced the pressure-induced contraction. In addition to the hitherto reported vasodilatory actions of fasudil, the present results suggest the inhibition by fasudil of pressure-induced tyrosine phosphorylation and pp60(src) activation. The wide spectrum of inhibitory actions of fasudil may contribute to the effective attenuation of the pressure-induced contraction in the cerebral artery.
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Affiliation(s)
- Naohiro Masumoto
- Department of Pharmacology, Faculty of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Shizuoka City, Shizuoka 422-8526, Japan
| | - Yoshiyuki Tanabe
- Department of Pharmacology, Faculty of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Shizuoka City, Shizuoka 422-8526, Japan
| | - Maki Saito
- Department of Pharmacology, Faculty of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Shizuoka City, Shizuoka 422-8526, Japan
| | - Koichi Nakayama
- Department of Pharmacology, Faculty of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Shizuoka City, Shizuoka 422-8526, Japan
- Author for correspondence:
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21
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Spurrell BE, Murphy TV, Hill MA. Tyrosine phosphorylation modulates arteriolar tone but is not fundamental to myogenic response. Am J Physiol Heart Circ Physiol 2000; 278:H373-82. [PMID: 10666067 DOI: 10.1152/ajpheart.2000.278.2.h373] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The present study investigated the role of protein tyrosine phosphorylation in myogenic responsiveness of rat skeletal muscle arterioles. Arteriolar segments were cannulated and pressurized without intraluminal flow. All vessels studied developed spontaneous tone and demonstrated significant myogenic constriction to step changes in pressure with a resultant increase in myogenic tone over an intraluminal pressure range of 50-150 mmHg. Step increases in intraluminal pressure from 50 to 120 mmHg caused a rapid and sustained elevation in intracellular [Ca(2+)], as measured using fura 2. Vessels with myogenic tone dilated in response to tyrosine kinase inhibitors genistein (10 or 30 microM) and tyrphostin A47 (10 or 30 microM) and constricted to the tyrosine phosphatase inhibitor pervanadate (1 or 10 microM). Despite the dilator effect, myogenic reactivity was not blocked by the inhibitors. Daidzein (10 microM), a compound structurally similar to genistein but without tyrosine kinase-inhibiting activity, did not alter vessel tone or myogenic responses. Preincubation of arterioles with genistein or tyrphostin A47 did not significantly alter baseline arteriolar [Ca(2+)], and neither drug reduced the increase in [Ca(2+)] following an acute increase in intraluminal pressure. Constriction induced by pervanadate (10 microM) was not accompanied by a significant increase in intracellular [Ca(2+)], even though removal of extracellular Ca(2+) reversed the constriction. Examination of smooth muscle tyrosine phosphorylation, using a fluorescent phosphotyrosine antibody and confocal microscopy, showed that increased intraluminal pressure resulted in an increase in anti-phosphotyrosine fluorescence. Because manipulation of tyrosine kinase activity was found to alter vessel diameter, these data support a role for tyrosine phosphorylation in modulation of arteriolar tone. However, the results indicate that acute arteriolar myogenic constriction does not require tyrosine phosphorylation.
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Affiliation(s)
- B E Spurrell
- Microvascular Biology Group, Department of Human Biology and Movement Science, RMIT University, Bundoora, Victoria 3083, Australia
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22
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Grover AK, Samson SE, Misquitta CM, Elmoselhi AB. Effects of peroxide on contractility of coronary artery rings of different sizes. Mol Cell Biochem 1999; 194:159-64. [PMID: 10391135 DOI: 10.1023/a:1006902603056] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Reactive oxygen species (ROS, free radicals) produced during cardiac ischemia and reperfusion can damage the contractile functions of arteries. The sarcoplasmic reticulum (SR) Ca2+ pump in coronary artery smooth muscle is very sensitive to ROS. Here we show that contractions of de-endothelialized rings from porcine left coronary artery produced by the hormone Angiotensin II and by the SR Ca2+ pump inhibitors cyclopiazonic acid and thapsigargin correlate negatively with the tissue weight. In contrast, the contractions due to membrane depolarization by high KCl correlate positively. Peroxide also produces a small contraction which correlates negatively with the tissue weight. When artery rings are treated with peroxide and washed, their ability to contract with Angiotensin II, cyclopiazonic acid and thapsigargin decreases. Thus, the SR Ca2+ pump may play a more important role in the contractility of the smaller segments of the coronary artery than in the larger segments. These results are consistent with the hypothesis that ROS which damage the SR Ca2+ pump affect the contractile function of the distal segments more adversely than of the proximal segments.
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Affiliation(s)
- A K Grover
- Department of Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
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23
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Hughes AD, Wijetunge S. Role of tyrosine phosphorylation in excitation-contraction coupling in vascular smooth muscle. ACTA PHYSIOLOGICA SCANDINAVICA 1998; 164:457-69. [PMID: 9887969 DOI: 10.1046/j.1365-201x.1998.00446.x] [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: 11/20/2022]
Abstract
Increasingly it is recognized that tyrosine phosphorylation plays an important part in the regulation of function in differentiated contractile vascular smooth muscle. Tyrosine kinases and phosphatases are present in large amounts in vascular smooth muscle and have been reported to influence a number of processes crucial to contraction, including ion channel gating, calcium homeostasis and sensitization of the contractile process to [Ca2+]i. This review summarizes current understanding regarding the role of tyrosine phosphorylation in excitation-contraction coupling in blood vessels.
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Affiliation(s)
- A D Hughes
- National Heart and Lung Institute, Imperial College of Science, Technology and Medicine, St Mary's Hospital, London, UK
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24
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Goto T, Yanaga F, Ohtsuki I. Studies on the endothelin-1-induced contraction of rat granulation tissue pouch mediated by myofibroblasts. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1405:55-66. [PMID: 9784605 DOI: 10.1016/s0167-4889(98)00105-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
A granulation tissue pouch, mostly composed of myofibroblasts, was prepared by injecting rats subcutaneously with croton oil. The contraction of the granulation tissue pouch caused by endothelin-1 (ET-1) and the effects of the ET receptor antagonists, BQ123 and BQ788 on it were thus examined. ET-1 produced contractions in a dose-dependent manner. Pretreatment with BQ123, an ETA receptor selective antagonist, shifted the dose-response curve to the right, whereas pretreatment with BQ788, an ETB receptor selective antagonist, showed little effect. IRL1620, an ETB receptor selective agonist, did not cause any contraction in the granulation tissue pouch. The existence of both ETA and ETB receptors in the granulation tissue pouch and in cultured myofibroblasts was demonstrated by RT-PCR. Intracellular Ca2+ mobilization in Fura-2/acetyl-methoxy ester loaded cultured myofibroblasts isolated from the granulation tissue was also examined. ET-1 produced a transient increase in [Ca2+]i followed by a sustained elevation of [Ca2+]i, whereas IRL1620 caused only a transient peak. These results suggest that the ET-1 induced contraction of granulation tissue is mainly mediated through the mobilization of Ca2+ from the extracellular space caused by stimulation with ETA receptor.
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Affiliation(s)
- T Goto
- Department of Clinical Pharmacology, Faculty of Medicine, Kyushu University, Fukuoka 812-8582, Japan
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25
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Peng W, Michael JR, Hoidal JR, Karwande SV, Farrukh IS. ET-1 modulates KCa-channel activity and arterial tension in normoxic and hypoxic human pulmonary vasculature. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 275:L729-39. [PMID: 9755105 DOI: 10.1152/ajplung.1998.275.4.l729] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The molecular mechanisms by which endothelin (ET)-1 induces pulmonary hypertension are poorly understood. We investigated the effects of ET-1 on outward K+ currents of normoxic and chronically hypoxic human pulmonary arterial (PA) smooth muscle cells (HPSMCs). In normoxic HPSMCs, ET-1 has dual effects. In intact cells, 5 nM ET-1 activates the large-conductance and Ca2+-activated K+ (KCa)-channel current [IK(Ca)] by increasing intracellular Ca2+ concentration, whereas it directly inhibits IK(Ca) in isolated membrane patches. At a higher concentration (10 nM), ET-1-induced IK(Ca) inhibition predominates. In hypoxic HPSMCs, ET-1 at 5 nM significantly reduces IK(Ca). The ETA-receptor antagonist BQ-123 reverses the ET-1-induced decrease in IK(Ca). Chronic BQ-123 treatment also prevents the hypoxia-induced decrease in IK(Ca). In PA rings obtained from human organ donors, ET-1 causes a concentration-dependent increase in tension. The ET-1-mediated increase in tension is reversed by a KCa-channel agonist. The increase in tension at the highest concentration studied (9 nM) was more pronounced in PA rings obtained from patients with chronic obstructive pulmonary disease. These results imply that an ET-1-induced decrease in IK(Ca) contributes to chronic hypoxia-induced pulmonary hypertension.
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MESH Headings
- 4-Aminopyridine/pharmacology
- Analysis of Variance
- Cell Hypoxia/physiology
- Cells, Cultured
- Charybdotoxin/pharmacology
- Dehydroepiandrosterone/pharmacology
- Dose-Response Relationship, Drug
- Endothelin Receptor Antagonists
- Endothelin-1/pharmacology
- Endothelin-1/physiology
- Humans
- In Vitro Techniques
- Kinetics
- Large-Conductance Calcium-Activated Potassium Channels
- Lung Diseases, Obstructive/physiopathology
- Membrane Potentials/drug effects
- Membrane Potentials/physiology
- Muscle Contraction/drug effects
- Muscle Contraction/physiology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/physiology
- Muscle, Smooth, Vascular/physiopathology
- Patch-Clamp Techniques
- Peptides, Cyclic/pharmacology
- Potassium Channels/drug effects
- Potassium Channels/physiology
- Potassium Channels, Calcium-Activated
- Pulmonary Artery/drug effects
- Pulmonary Artery/physiology
- Pulmonary Artery/physiopathology
- Receptor, Endothelin A
- Thapsigargin/pharmacology
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Affiliation(s)
- W Peng
- Division of Respiratory, Critical Care, and Occupational Medicine, Department of Internal Medicine, The University of Utah Health Sciences Center, Salt Lake City, Utah 84132, USA
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