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Sporkova A, Nahar T, Cao M, Ghosh S, Sens-Albert C, Friede PAP, Nagel A, Al-Hasani J, Hecker M. Characterisation of Lipoma-Preferred Partner as a Novel Mechanotransducer in Vascular Smooth Muscle Cells. Cells 2023; 12:2315. [PMID: 37759537 PMCID: PMC10529303 DOI: 10.3390/cells12182315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 08/29/2023] [Accepted: 09/15/2023] [Indexed: 09/29/2023] Open
Abstract
In arteries and arterioles, a chronic increase in blood pressure raises wall tension. This continuous biomechanical strain causes a change in gene expression in vascular smooth muscle cells (VSMCs) that may lead to pathological changes. Here we have characterised the functional properties of lipoma-preferred partner (LPP), a Lin11-Isl1-Mec3 (LIM)-domain protein, which is most closely related to the mechanotransducer zyxin but selectively expressed by smooth muscle cells, including VSMCs in adult mice. VSMCs isolated from the aorta of LPP knockout (LPP-KO) mice displayed a higher rate of proliferation than their wildtype (WT) counterparts, and when cultured as three-dimensional spheroids, they revealed a higher expression of the proliferation marker Ki 67 and showed greater invasion into a collagen gel. Accordingly, the gelatinase activity was increased in LPP-KO but not WT spheroids. The LPP-KO spheroids adhering to the collagen gel responded with decreased contraction to potassium chloride. The relaxation response to caffeine and norepinephrine was also smaller in the LPP-KO spheroids than in their WT counterparts. The overexpression of zyxin in LPP-KO VSMCs resulted in a reversal to a more quiescent differentiated phenotype. In native VSMCs, i.e., in isolated perfused segments of the mesenteric artery (MA), the contractile responses of LPP-KO segments to potassium chloride, phenylephrine or endothelin-1 did not vary from those in isolated perfused WT segments. In contrast, the myogenic response of LPP-KO MA segments was significantly attenuated while zyxin-deficient MA segments displayed a normal myogenic response. We propose that LPP, which we found to be expressed solely in the medial layer of different arteries from adult mice, may play an important role in controlling the quiescent contractile phenotype of VSMCs.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Markus Hecker
- Department of Cardiovascular Physiology, Heidelberg University, Im Neuenheimer Feld 326, 69120 Heidelberg, Germany; (A.S.)
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Kua KP, Lee SWH. Systematic review and meta-analysis of clinical outcomes of early caffeine therapy in preterm neonates. Br J Clin Pharmacol 2017; 83:180-191. [PMID: 27526255 PMCID: PMC5338164 DOI: 10.1111/bcp.13089] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Revised: 08/01/2016] [Accepted: 08/08/2016] [Indexed: 12/18/2022] Open
Abstract
AIMS This study evaluated the therapeutic outcomes of early versus late caffeine therapy in preterm neonates. METHODS We performed a systematic literature search in PubMed, Embase, CINAHL and CENTRAL from inception to 30 June 2016 to identify studies investigating the use of early caffeine therapy (initiated at less than 3 days of life) in preterm infants. Effect estimates were combined using random-effects meta-analysis. The primary outcomes for this study were bronchopulmonary dysplasia and mortality. RESULTS The initial search found 4066 citations, of which 14 studies enrolling a total of 64 438 participants were included. The time of initiation of early caffeine therapy varied from the first 2 h to 3 days postnatal. Early caffeine therapy reduced the risk of bronchopulmonary dysplasia in both cohort studies (RR: 0.80, 95% CI: 0.66 to 0.96) and randomized controlled trials (RR: 0.67, 95% CI: 0.56 to 0.81). In cohort studies, neonates treated early with caffeine also showed decreased risks of patent ductus arteriosus, brain injury, retinopathy of prematurity and postnatal steroid use. However, the mortality rate was increased. CONCLUSIONS The findings suggest that early caffeine therapy is associated with reduced incidence of bronchopulmonary dysplasia and may help decrease the burden of morbidities in preterm infants.
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Affiliation(s)
- Kok Pim Kua
- School of PharmacyMonash University MalaysiaSelangor Darul EhsanMalaysia
| | - Shaun Wen Huey Lee
- School of PharmacyMonash University MalaysiaSelangor Darul EhsanMalaysia
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Mani BK, Robakowski C, Brueggemann LI, Cribbs LL, Tripathi A, Majetschak M, Byron KL. Kv7.5 Potassium Channel Subunits Are the Primary Targets for PKA-Dependent Enhancement of Vascular Smooth Muscle Kv7 Currents. Mol Pharmacol 2015; 89:323-34. [PMID: 26700561 DOI: 10.1124/mol.115.101758] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Accepted: 12/18/2015] [Indexed: 12/11/2022] Open
Abstract
Kv7 (KCNQ) channels, formed as homo- or heterotetramers of Kv7.4 and Kv7.5 α-subunits, are important regulators of vascular smooth muscle cell (VSMC) membrane voltage. Recent studies demonstrate that direct pharmacological modulation of VSMC Kv7 channel activity can influence blood vessel contractility and diameter. However, the physiologic regulation of Kv7 channel activity is still poorly understood. Here, we study the effect of cAMP/protein kinase A (PKA) activation on whole cell K(+) currents through endogenous Kv7.5 channels in A7r5 rat aortic smooth muscle cells or through Kv7.4/Kv7.5 heteromeric channels natively expressed in rat mesenteric artery smooth muscle cells. The contributions of specific α-subunits are further dissected using exogenously expressed human Kv7.4 and Kv7.5 homo- or heterotetrameric channels in A7r5 cells. Stimulation of Gαs-coupled β-adrenergic receptors with isoproterenol induced PKA-dependent activation of endogenous Kv7.5 currents in A7r5 cells. The receptor-mediated enhancement of Kv7.5 currents was mimicked by pharmacological agents that increase [cAMP] (forskolin, rolipram, 3-isobutyl-1-methylxanthine, and papaverine) or mimic cAMP (8-bromo-cAMP); the 2- to 4-fold PKA-dependent enhancement of currents was also observed with exogenously expressed Kv7.5 channels. In contrast, exogenously-expressed heterotetrameric Kv7.4/7.5 channels in A7r5 cells or native mesenteric artery smooth muscle Kv7.4/7.5 channels were only modestly enhanced, and homo-tetrameric Kv7.4 channels were insensitive to this regulatory pathway. Correspondingly, proximity ligation assays indicated that isoproterenol induced PKA-dependent phosphorylation of exogenously expressed Kv7.5 channel subunits, but not of Kv7.4 subunits. These results suggest that signal transduction-mediated responsiveness of vascular smooth muscle Kv7 channel subunits to cAMP/PKA activation follows the order of Kv7.5 >> Kv7.4/Kv7.5 > Kv7.4.
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Affiliation(s)
- Bharath K Mani
- Department of Molecular Pharmacology and Therapeutics (B.K.M., C.R., L.I.B., M.M., K.L.B.), Department of Cell and Molecular Physiology (L.L.C.), and Department of Surgery (A.T., M.M.), Loyola University Chicago, Maywood, Illinois
| | - Christina Robakowski
- Department of Molecular Pharmacology and Therapeutics (B.K.M., C.R., L.I.B., M.M., K.L.B.), Department of Cell and Molecular Physiology (L.L.C.), and Department of Surgery (A.T., M.M.), Loyola University Chicago, Maywood, Illinois
| | - Lyubov I Brueggemann
- Department of Molecular Pharmacology and Therapeutics (B.K.M., C.R., L.I.B., M.M., K.L.B.), Department of Cell and Molecular Physiology (L.L.C.), and Department of Surgery (A.T., M.M.), Loyola University Chicago, Maywood, Illinois
| | - Leanne L Cribbs
- Department of Molecular Pharmacology and Therapeutics (B.K.M., C.R., L.I.B., M.M., K.L.B.), Department of Cell and Molecular Physiology (L.L.C.), and Department of Surgery (A.T., M.M.), Loyola University Chicago, Maywood, Illinois
| | - Abhishek Tripathi
- Department of Molecular Pharmacology and Therapeutics (B.K.M., C.R., L.I.B., M.M., K.L.B.), Department of Cell and Molecular Physiology (L.L.C.), and Department of Surgery (A.T., M.M.), Loyola University Chicago, Maywood, Illinois
| | - Matthias Majetschak
- Department of Molecular Pharmacology and Therapeutics (B.K.M., C.R., L.I.B., M.M., K.L.B.), Department of Cell and Molecular Physiology (L.L.C.), and Department of Surgery (A.T., M.M.), Loyola University Chicago, Maywood, Illinois
| | - Kenneth L Byron
- Department of Molecular Pharmacology and Therapeutics (B.K.M., C.R., L.I.B., M.M., K.L.B.), Department of Cell and Molecular Physiology (L.L.C.), and Department of Surgery (A.T., M.M.), Loyola University Chicago, Maywood, Illinois
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Tazzeo T, Bates G, Roman HN, Lauzon AM, Khasnis MD, Eto M, Janssen LJ. Caffeine relaxes smooth muscle through actin depolymerization. Am J Physiol Lung Cell Mol Physiol 2012; 303:L334-42. [PMID: 22683573 DOI: 10.1152/ajplung.00103.2012] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Caffeine is sometimes used in cell physiological studies to release internally stored Ca(2+). We obtained evidence that caffeine may also act through a different mechanism that has not been previously described and sought to examine this in greater detail. We ruled out a role for phosphodiesterase (PDE) inhibition, since the effect was 1) not reversed by inhibiting PKA or adenylate cyclase; 2) not exacerbated by inhibiting PDE4; and 3) not mimicked by submillimolar caffeine nor theophylline, both of which are sufficient to inhibit PDE. Although caffeine is an agonist of bitter taste receptors, which in turn mediate bronchodilation, its relaxant effect was not mimicked by quinine. After permeabilizing the membrane using β-escin and depleting the internal Ca(2+) store using A23187, we found that 10 mM caffeine reversed tone evoked by direct application of Ca(2+), suggesting it functionally antagonizes the contractile apparatus. Using a variety of molecular techniques, we found that caffeine did not affect phosphorylation of myosin light chain (MLC) by MLC kinase, actin-filament motility catalyzed by MLC kinase, phosphorylation of CPI-17 by either protein kinase C or RhoA kinase, nor the activity of MLC-phosphatase. However, we did obtain evidence that caffeine decreased actin filament binding to phosphorylated myosin heads and increased the ratio of globular to filamentous actin in precontracted tissues. We conclude that, in addition to its other non-RyR targets, caffeine also interferes with actin function (decreased binding by myosin, possibly with depolymerization), an effect that should be borne in mind in studies using caffeine to probe excitation-contraction coupling in smooth muscle.
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Affiliation(s)
- Tracy Tazzeo
- Firestone Institute for Respiratory Health, St. Joseph’s Hospital and the Department of Medicine, McMaster University, Hamilton, Ontario, Canada
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Abstract
Naturally occurring methylxanthines were the first inhibitors of cyclic nucleotide (cN) phosphodiesterases (PDEs) to be discovered. To improve potency and specificity for inhibition of various PDEs in research and for treatment of diseases, thousands of compounds with related structures have now been synthesized. All known PDE inhibitors contain one or more rings that mimic the purine in the cN substrate and directly compete with cN for access to the catalytic site; this review focuses on inhibitors that contain a nucleus that is closely related to the xanthine ring of theophylline and caffeine and the purine ring of cNs. The specificity and potency of these compounds for blocking PDE action have been improved by appending groups at positions on the rings as well as by modification of the number and distribution of nitrogens and carbons in those rings. Several of these inhibitors are highly selective for particular PDEs; potent and largely selective PDE5 inhibitors are used clinically for treatment of erectile dysfunction [sildenafil (Viagra™), tadalafil (Cialis™) and vardenafil (Levitra™)] and pulmonary hypertension [sildenafil (Revatio™) and tadalafil (Adenocirca)]. Related compounds target other PDEs and show therapeutic promise for a number of maladies.
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Affiliation(s)
- Sharron H Francis
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232-0615, USA.
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Abstract
The G2 phase/mitosis transition in cleavage-stage mouse embryos is correlated with an increased phosphorylation of a defined set of proteins at 46, 35, 30, and 29 kDa. Cell cleavage and the associated changes in protein phosphorylation are delayed after X-irradiation. To understand the mechanism of the caffeine-induced uncoupling of mitosis and the cellular reactions to DNA-damaging agents, we have studied the effects of caffeine treatment on cell cycle progression and protein phosphorylation in two-cell mouse embryos after X-irradiation. Caffeine alone had no effect on timing of and changes in phosphorylation associated with the embryonic cell cycle. In combination with X-rays, however, caffeine was able to override the radiation induced G2 block and restored the normal timing of these phosphorylation changes after X-irradiation. However, new additional changes in protein phosphorylation appeared after the combined treatment. Isobutylmethylxanthine (IBMX), a substance chemically related to caffeine but a more specific inhibitor of the phosphodiesterase that breaks down cyclic AMP, reduced the radiation induced G2 block from 4 to 5 h to about 1 h and restored the cell cycle associated changes in protein phosphorylation. However, the same new changes which appeared after the combined treatment of caffeine and X-rays were observed after the combination of IBMX and X-irradiation. IBMX specific changes in protein phosphorylation were detected in both the single and the combined treatment. These results indicate a similar action of caffeine and IBMX in overriding the radiation induced G2 block in two-cell mouse embryos.
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Affiliation(s)
- T Jung
- Department of Molecular Embryology, AFRC Institute of Animal Physiology and Genetics Research, Babraham, Cambridge, UK
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Ng WW, Keung W, Xu YC, Ng KF, Leung GP, Vanhoutte PM, Choy PC, Man RY. Genistein potentiates protein kinase A activity in porcine coronary artery. Mol Cell Biochem 2008; 311:37-44. [PMID: 18165926 DOI: 10.1007/s11010-007-9691-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2007] [Accepted: 12/16/2007] [Indexed: 10/22/2022]
Abstract
Soy consumption is associated with a lower risk of atherosclerotic disease in the oriental population. Genistein is a soy isoflavone bearing estrogenic properties. Previous experiments in our laboratory demonstrated the potentiation of endothelium-independent relaxation of coronary artery by both estrogen and genistein. The potentiating effects of both estrogen and genistein were mediated through the cAMP-signaling pathway. We hypothesize that genistein could enhance protein kinase A (PKA) activity in porcine coronary artery smooth muscle, thereby offering a mechanism for the potentiation of vascular relaxation by genistein. In our study, a high concentration of genistein (10(-4.5) M) significantly increased PKA activity in porcine coronary artery rings. While genistein at 10(-5.5) M and forskolin at 10(-7) M had no effect on PKA activity, the combination of the two compounds at the prescribed concentrations caused a significant increase in PKA activity. The increase in PKA activity by genistein was abolished by SQ 22536 (adenylate cyclase blocker), but not by NF 449 (Gs protein blocker) or ICI 182780 (estrogen receptor antagonist). Our results suggest that the action of genistein is mediated via adenylate cyclase, but does not appear to involve Gs protein or ICI 182780-sensitive estrogen receptor.
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Abstract
Caffeine and other methyl xanthines are widely used in the neonatal period. A recent, randomized, placebo-controlled, multicenter trial found that infants who were randomly assigned to caffeine treatment had less need for pharmacologic and/or surgical closure of a patent ductus arteriosus (PDA). We hypothesized that the decreased need for pharmacologic and surgical closure of the PDA after caffeine treatment might be due to a direct effect of caffeine on ductus contractility. We examined preterm fetal lamb ductus arteriosus (from 24 fetuses, 105 +/- 4 d of gestation, term = 147 d), in vitro to determine the direct effects of caffeine on the isometric tension of the ductus arteriosus. Caffeine (0.003-0.3 mM) had no direct effect on ductus arteriosus tension, nor did it affect the contractile response of the ductus arteriosus to increasing oxygen concentrations. Caffeine's lack of effect was observed in both the presence and absence of indomethacin and NG-nitro-L-arginine methyl ester (L-NAME) (inhibitors of prostaglandin and nitric oxide production). In conclusion, we found no evidence of a direct effect of therapeutic caffeine concentrations on ductus contractility.
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MESH Headings
- Animals
- Caffeine/pharmacology
- Cardiovascular Agents/pharmacology
- Cardiovascular Agents/therapeutic use
- Cyclooxygenase Inhibitors/pharmacology
- Dose-Response Relationship, Drug
- Ductus Arteriosus/drug effects
- Ductus Arteriosus/embryology
- Ductus Arteriosus/enzymology
- Ductus Arteriosus/metabolism
- Ductus Arteriosus, Patent/drug therapy
- Ductus Arteriosus, Patent/embryology
- Ductus Arteriosus, Patent/metabolism
- Ductus Arteriosus, Patent/physiopathology
- Female
- Gestational Age
- Indomethacin/pharmacology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/embryology
- Muscle, Smooth, Vascular/enzymology
- Muscle, Smooth, Vascular/metabolism
- NG-Nitroarginine Methyl Ester/pharmacology
- Nitric Oxide/metabolism
- Nitric Oxide Synthase/antagonists & inhibitors
- Nitric Oxide Synthase/metabolism
- Oxygen/metabolism
- Pregnancy
- Prostaglandins/metabolism
- Sheep
- Vasoconstriction/drug effects
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Affiliation(s)
- Ronald I Clyman
- Cardiovascular Research Institute and Department of Pediatrics, University of California San Francisco, San Francisco, California 94143, USA.
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Tong Z, Chen B, Dai H, Bauer PC, Guzman J, Costabel U. Extrinsic allergic alveolitis: inhibitory effects of pentoxifylline on cytokine production by alveolar macrophages. Ann Allergy Asthma Immunol 2004; 92:234-9. [PMID: 14989392 DOI: 10.1016/s1081-1206(10)61553-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Pentoxifylline is a well-established drug with hemorheologic properties. Various evidence suggests an additional therapeutic potential in regard to inflammation and immunomodulation. Extrinsic allergic alveolitis (EAA) is a granulomatous disease that is driven by T-cell and alveolar macrophage (AM)-derived cytokines. OBJECTIVE To investigate the effects of pentoxifylline on the production of tumor necrosis factor (TNF) alpha, interleukin (IL) 1beta, IL-6, IL-8, IL-10, and the soluble TNF receptors (sTNFR1 and sTNFR2) from AMs in EAA compared with dexamethasone. METHODS The AMs from 9 patients with EAA were cultured for 24 hours with RPMI medium alone or lipopolysaccharide (LPS) (100 ng/mL) and with pentoxifylline at concentrations of 0.01, 0.1, and 1 mmol/L or 0.1-mmol/L dexamethasone. Cytokines in the culture supernatants were analyzed by enzyme-linked immunosorbent assay. RESULTS Pentoxifylline induced a dose-dependent suppression of spontaneous TNF-alpha and IL-10 release from AMs in EAA. The spontaneous production of other cytokines was unaffected by pentoxifylline at all tested concentrations. Dexamethasone inhibited significantly only the spontaneous release of TNF-alpha. Pentoxifylline and dexamethasone also inhibited the LPS-stimulated production of all cytokines except IL-1beta and sTNFR1. CONCLUSION Our results may be the basis for clinical trials to evaluate the role of pentoxifylline as an immunotherapeutic agent in the treatment of EAA.
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Affiliation(s)
- Zhaohui Tong
- Department of Pneumology and Allergy, Ruhrlandklinik, Medical Faculty, University of Essen, Essen, Germany
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Tong Z, Dai H, Chen B, Abdoh Z, Guzman J, Costabel U. Inhibition of cytokine release from alveolar macrophages in pulmonary sarcoidosis by pentoxifylline: comparison with dexamethasone. Chest 2003; 124:1526-32. [PMID: 14555589 DOI: 10.1378/chest.124.4.1526] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
STUDY OBJECTIVES Pentoxifylline (POF) has been shown to suppress the cytokine production from lipopolysaccharide (LPS)-stimulated monocytes/alveolar macrophages (AMs). Sarcoidosis is a granulomatous disease that is driven by the action of tumor necrosis factor (TNF)-alpha and other proinflammatory cytokines. In this study, we aimed to investigate the effects of POF on the production of TNF-alpha, interleukin (IL)-1 beta, IL-6, IL-8, IL-10, and the soluble TNF receptors (sTNFRs) 1 and 2 from AMs in sarcoidosis, and we also compared them with those of dexamethasone (DEX). METHODS AMs from 14 patients with sarcoidosis were cultured for 24 h with RPMI medium alone or with LPS (100 ng/mL), and with POF at concentrations of 0.01, 0.1, and 1 mmol/L, or with 0.1 mmol/L DEX. Cytokines in the culture supernatants were analyzed by enzyme-linked immunosorbent assay. RESULTS The results showed that POF induced a dose-dependent suppression of the spontaneous TNF-alpha release from AMs in sarcoidosis (p < 0.001), and that the spontaneous release of the other cytokines was unaffected by POF at all tested concentrations, but a trend for the inhibition of IL-10 production was found (p = 0.092). DEX inhibited the spontaneous release of TNF-alpha (p < 0.001), sTNFR2 (p < 0.05), IL-1 beta (p < 0.05), and IL-10 (p < 0.01). POF also suppressed the LPS-stimulated production of these cytokines except for that of sTNFR1. Similar to POF, DEX inhibited the LPS-stimulated production of these cytokines, but not that of sTNFR1 and IL-1 beta. CONCLUSIONS Compared with DEX, POF may improve therapeutic regimens in patients with sarcoidosis either by sparing or by replacing corticosteroids. However, the precise clinical value of POF in the treatment of sarcoidosis and other lung diseases will have to be determined in further clinical trials.
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Affiliation(s)
- Zhaohui Tong
- Department of Pneumology and Allergy, Ruhrlandklinik, Medical Faculty, University of Essen, Essen, Germany
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Deshpande RV, Peterson RH, Moore MA. Granulocyte colony-stimulating factor activates protein kinase A in granulocytic but not monocytic precursors or neutrophils. J Interferon Cytokine Res 1998; 18:579-86. [PMID: 9726439 DOI: 10.1089/jir.1998.18.579] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
Granulocyte colony-stimulating factor (G-CSF) regulates survival, proliferation, differentiation, and activation of myeloid cells. G-CSF-R signaling mechanisms other than tyrosine kinase activation have not been documented. We explored the potential involvement of cAMP-dependent protein kinase A (PKA) in G-CSF-R signal transduction. In this report, we provide the first direct evidence of PKA modulation by G-CSF-R. G-CSF treatment of granulocytic precursor cell lines (HL-60, NFS-60, KG-1) resulted in PKA activation, measured by phosphorylation of Kemptide, a peptide substrate. In contrast, the myelomonocytic cell lines (WEHI-3B,U-937) and peripheral blood neutrophils (PMNC) showed a rapid decrease in PKA activity in response to G-CSF. H-89, a specific inhibitor of PKA, blocked G-CSF-induced PKA activation in HL-60 cells but did not affect ligand-induced downmodulation of G-CSF-R. Indomethacin, an inhibitor of the cyclooxygenase pathway and prostaglandin synthesis, did not inhibit PKA induction in G-CSF-treated HL-60 cells. Our results demonstrate the involvement of PKA in G-CSF-R signal transduction and suggest a lineage-restricted, developmental stage-specific regulation of this pathway in myeloid cells.
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Affiliation(s)
- R V Deshpande
- James Ewing Laboratory of Developmental Hematopoiesis, Program of Cell Biology and Genetics, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA.
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D'Hellencourt CL, Diaw L, Cornillet P, Guenounou M. Differential regulation of TNF alpha, IL-1 beta, IL-6, IL-8, TNF beta, and IL-10 by pentoxifylline. Int J Immunopharmacol 1996; 18:739-48. [PMID: 9172017 DOI: 10.1016/s0192-0561(97)85556-7] [Citation(s) in RCA: 77] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Pentoxifylline (PTX) is a methylxanthine drug known to inhibit the production of tumor necrosis factor-alpha (TNF alpha), which plays a key role in inflammation. Recent studies also revealed that other cytokines may be inhibited by PTX. We investigated PTX effects on production and mRNA expression of TNF alpha, IL-1 beta, IL-6, IL-8, TNF beta and IL-10. Cytokine release was studied in 1/10 diluted whole blood culture (WB) and in peripheral blood mononuclear cell (PBMC) culture. Cytokine production was triggered in both culture systems by endotoxin (LPS) or by phorbol ester (PMA) plus phytohemagglutinin (PHA). Our results showed that expression and production of TNF alpha and TNF beta were inhibited by PTX in a dose-dependent manner. Moreover, we observed that depending on the way of activating cells, PTX induced an up- or a down-regulation (in PMA + PHA or LPS stimulated cells, respectively) for IL-1 and IL-6 release. We also noted that the effects of PTX on IL-6, IL-8 and IL-10 production were different in WB and in PBMC culture. In conclusion PTX acts on cytokine in a complex manner depending on cellular environment and on the method of activation.
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Abstract
Four hypotheses were tested using isolated bovine oocytes. (1) Cumulus oocyte complexes (COCs) or denuded oocytes (DOs) were cultured with the protein kinase A (PKA) inhibitor, H-89, to test if meiotic arrest induced by forskolin or IBMX was due to cAMP-stimulated PKA activity or nonspecific effects of these cAMP elevators. (2) COCs were cultured with a protein kinase C (PKC) stimulator (PDD beta) or inhibitor (GF109203x) to test if PKC modulation altered oocyte maturation. (3) COCs were prestimulated for 15 min with (a) PDD beta followed by cotreatment with forskolin, or (b) with H-89 or H-7 followed by cotreatment with GF109203x, to test for interaction between the PKA and PKC signal transduction pathways. (4) H-89 was added to spontaneously maturing COCs at intervals of 0-18 hr to test if H-89 interfered with the transition between meiosis I and II. The results were as follows: H-89 interfered with forskolin or IBMX arrested oocytes in dose-response manner (IBMX ED50 = 41 microM for COCs; forskolin ED50 = 9 microM for denuded oocytes). Prestimulation with PKC induced meiotic resumption in COCs in spite of the presence of forskolin [PDD beta followed by PDD beta + forskolin: 41-47% germinal vesicle (GV) oocytes; forskolin alone: 90-95% GV], while PKC inhibition induced meiotic arrest to a similar extent as forskolin (GF109203x, 85% GV; forskolin, 67-80% GV). Additionally, pretreatment of COCs with H-89 interfered with GF109203x induced arrest (41% vs. 90% GV, respectively). Finally, H-89 interfered with the timely progression of COCs from meiosis I and II. These results indicate that the PKA and PKC pathways can modulate the maturation of bovine oocytes in vitro.
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Affiliation(s)
- T A Rose-Hellekant
- Department of Animal Health and Biomedical Sciences, University of Wisconsin-Madison 53706, USA
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McLean PG, Coupar IM. Further investigation into the signal transduction mechanism of the 5-HT4-like receptor in the circular smooth muscle of human colon. Br J Pharmacol 1996; 118:1058-64. [PMID: 8799582 PMCID: PMC1909528 DOI: 10.1111/j.1476-5381.1996.tb15506.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
1. The nature of the receptor coupling mechanism of the 5-hydroxytryptamine4 (5-HT4) receptor in the circular smooth muscle of the human colon has been further investigated. 2. 5-HT stimulated cyclic AMP generation and caused a relaxation in a concentration-dependent fashion, with EC50 values of 175.5 and 274.9 nM respectively. DAU 6236 increased cyclic AMP formation and caused a relaxant effect but was a partial agonist relative to 5-HT. 3. The 5-HT4 receptor antagonist, GR 113808, inhibited cyclic AMP formation and relaxation induced by 5-HT with -log Ki values of 9.1 (cyclic AMP) and 8.9 (relaxation) and apparent pA2 values of 9.2 (cyclic AMP) and 9.5 (relaxation). 4. Ondansetron and methysergide failed to inhibit cyclic AMP formation or the relaxation induced by 5-HT. 5. The phosphodiesterase inhibitor, IBMX, produced a concentration-dependent relaxation (EC50 = 30 microM) and at 1 microM it enhanced the 5-HT-induced relaxation producing a leftward shift of the 5-HT concentration-effect curve with a concentration-ratio of 4.1. Rolipram caused a concentration-dependent relaxation (EC50 = 564.8 nM) and at 200 nm caused a leftward shift of the concentration-effect curve to 5-HT with a concentration-ratio of 5.5. 6. Application of the adenylyl cyclase inhibitor, SQ 22536 (0.1 mM), and the protein kinase inhibitors, H7 (100 nM) and H89 (200 nM), inhibited the relaxant effect of 5-HT inducing a rightward shift of the concentration-effect curve with concentration-ratios of 10.1, 2.7 and 4.2 respectively. 7. Forskolin stimulated cyclic AMP production and caused a relaxation. The maximum relaxant effect of forskolin (6 microM, 13.8 +/- 1.9 cm.s) was not significantly different from the maximum relaxant effect of 5-HT (10 microM, 12.7 +/- 4.9 cm.s). However, the cyclic AMP levels stimulated by forskolin (6 microM, 49.3 +/- 6.6 pmol mg-1) were markedly greater than those stimulated by 5-HT (10 microM, 7.6 +/- 2.0 pmol mg-1). 8. In conclusion, these results indicate that the 5-HT4 receptors of the circular smooth muscle of human colon mediate relaxation and inhibition of spontaneous contractions via activation of adenylyl cyclase, formation of cyclic AMP and activation of protein kinase A.
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Affiliation(s)
- P G McLean
- School of Pharmaceutical Biology and Pharmacology, Victorian College of Pharmacy, Monash University, Australia
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16
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Strassmann G, Patil-Koota V, Finkelman F, Fong M, Kambayashi T. Evidence for the involvement of interleukin 10 in the differential deactivation of murine peritoneal macrophages by prostaglandin E2. J Exp Med 1994; 180:2365-70. [PMID: 7525853 PMCID: PMC2191801 DOI: 10.1084/jem.180.6.2365] [Citation(s) in RCA: 284] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Among other effects, prostaglandins (PG) of the E series are known to inhibit several acute and chronic inflammatory conditions in vivo and proinflammatory cytokine production by activated macrophages in culture. The research presented here demonstrates that the inhibitory effect of PGE2 on tumor necrosis factor alpha (TNF-alpha) and interleukin 6 (IL-6) production by lipopolysaccharide (LPS)-stimulated murine peritoneal macrophages involves IL-10. In a dose-dependent manner, PGE2 inhibits LPS-induced release of TNF-alpha and IL-6, but not of lactate or nitric oxide. The decrease in the level of these cytokines is inversely proportional to the increase in immunoreactive IL-10. This differential inhibitory effect of PGE2 is mimicked by agents that elevate intracellular levels of cAMP, but not cGMP. Neutralizing anti IL-10 antibody but not neutralizing antibodies against other macrophage secretory products (IL-6, leukemia inhibitory factor, and transforming growth factor beta [TGF-beta]), significantly reverse the potent inhibitory effect of PGE2. In vivo, the administration of PGE2 before LPS challenge significantly reduces circulating TNF-alpha and IL-6 levels. Anti-IL-10 antibody substantially enhanced the LPS-induced TNF-alpha and IL-6 levels in mice that received either LPS alone or LPS plus PGE2. These results suggest that the anti-inflammatory effect of PGE2 on mononuclear phagocytes is mediated in part by an autocrine feedback mechanism involving IL-10.
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Affiliation(s)
- G Strassmann
- Department of Immunology, Otsuka-America Pharmaceutical Inc., Rockville, Maryland 20850
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17
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Tomes C, Rossi S, Moreno S. Isobutylmethylxanthine and other classical cyclic nucleotide phosphodiesterase inhibitors affect cAMP-dependent protein kinase activity. Cell Signal 1993; 5:615-21. [PMID: 7508732 DOI: 10.1016/0898-6568(93)90056-r] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The effect of 17 inhibitors of cyclic nucleotide phosphodiesterases (PDEs) was assayed on cAMP binding activity of Mucor rouxii protein kinase A (PKA), on PKA activity in the absence of cAMP and on free catalytic subunit (C) activity. Isobutylmethylxanthine (IBMX), SQ 20,009 and cilostamide, at 0.2 mM, behaved as partial agonists of cAMP since they inhibited binding of 0.15 microM [3H]cAMP to the regulatory subunit (R), stimulated slightly PKA activity in the absence of cAMP and did not modify C activity. Amrinone at 0.2 mM inhibited C activity competitively towards ATP. These four compounds displayed the same effects when assayed on eukaryotic protein kinase A types I (PKI) and II (PKII). The combined effect of IBMX and cAMP was analysed on Mucor PKA. Under dissociating conditions (+ 0.5 M NaCl) IBMX antagonized activation by low concentrations of cAMP, while in the absence of NaCl, IBMX potentiated the stimulating activity of cAMP.
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Affiliation(s)
- C Tomes
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Argentina
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18
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Tanimura A, Tojyo Y, Matsumoto Y. The cytosolic acidification in rat parotid cells is associated with an increase in cytosolic Ca2+ concentration. Jpn J Pharmacol 1993; 61:357-60. [PMID: 8320881 DOI: 10.1254/jjp.61.357] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
A transient decrease in cytosolic pH ([pH]i) in rat parotid cells was evoked by the addition of carbachol (CCh), phenylephrine, or substance P, whereas isoproterenol and dibutyryl cyclic AMP had little or no effect on [pH]i. The decrease in [pH]i induced by the Ca(2+)-mobilizing agonists was also observed in Ca(2+)-free medium, but not when the intracellular Ca2+ stores were previously depleted. Ionomycin and thapsigargin elicited a decrease in [pH]i with an increase in cytosolic Ca2+ concentration ([Ca2+]i). The protein kinase C activator and inhibitor had no effect on the agonist-induced decrease in [pH]i. These results suggest that the cytosolic acidification is associated with an increase in [Ca2+]i.
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Affiliation(s)
- A Tanimura
- Department of Dental Pharmacology, School of Dentistry, Higashi Nippon Gakuen University, Hokkaido, Japan
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19
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Ohia SE, Cheung YD, Bieger D, Triggle CR. Pharmacological profile of the 5-hydroxytryptamine receptor that mediates relaxation of rat oesophageal smooth muscle. Gen Pharmacol 1992; 23:649-58. [PMID: 1327946 DOI: 10.1016/0306-3623(92)90143-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
1. The pharmacological profile of the inhibitory 5-hydroxytryptamine (5-HT) receptor in rat oesophageal smooth muscle has been characterized by means of a series of agonists active at 5-HT1-, 5-HT2-, 5-HT3- and 5-HT4-receptor sites, and a broad range of antagonists. The possible involvement of cyclic nucleotides in the 5-HT response was also examined. 2. Under conditions of tone induced by muscarinic receptor activation, the upper two-thirds (proximal segment) of the oesophageal smooth muscle tunic was more sensitive to the inhibitory effects of 5-HT receptor agonists when compared with the distal region. 3. The inhibitory response to 5-HT was blocked by MDL 72222 (5-HT3 antagonist) and ICS 205-930 (5-HT3/5-HT4 antagonist) but not by antagonists active at 5-HT1- or 5-HT2-receptors. 4. The phosphodiesterase inhibitor, 3-isobutyl-methyl-xanthine (IBMX) enhanced oesophageal smooth muscle inhibitory response to 5-HT, isoprenaline and forskolin, but not that elicited by the potassium channel opener, BRL 34915. 5. 5-HT increased tissue cyclic AMP content over basal levels in proximal and distal segments of oesophageal smooth muscle. However, 5-HT had no significant effect on basal cyclic GMP levels in both segments. 6. We conclude that the inhibitory 5-HT receptor in rat oesophageal smooth muscle may represent a high affinity subtype which is sensitive to 5-HT3/5-HT4 antagonists and is coupled to the cyclic AMP pathway.
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Affiliation(s)
- S E Ohia
- Division of Basic Medical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St John's, Canada
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20
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Salvemini D, Radziszewski W, Korbut R, Vane J. The use of oxyhaemoglobin to explore the events underlying inhibition of platelet aggregation induced by NO or NO-donors. Br J Pharmacol 1990; 101:991-5. [PMID: 1707709 PMCID: PMC1917820 DOI: 10.1111/j.1476-5381.1990.tb14194.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
1. Full inhibition of thrombin-induced platelet aggregation was elicited by the least maximal platelet inhibitory concentrations of nitric oxide (NO; 7 +/- 1 microM) or NO-donors which included sodium nitroprusside (NaNp; 80 +/- 13 microM) 3-morpholinosydnonimine (SIN-1; 3 +/- 0.1 microM) or endothelial cells (EC; 2.36 +/- 0.12 x 10(5) added 1 min before thrombin. Oxyhaemoglobin (oxyHb; 10 microM) administered 30s to 10 min after stimulation with thrombin caused a time-dependent reversal of the inhibition induced by these agents. OxyHb was ineffective when these agents were co-incubated with the non-selective phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX, 0.05 mM). 2. OxyHb did not reverse the platelet inhibition with IBMX (0.2 mM) or that caused by a selective guanosine 3'; 5'-cyclic monophosphate (cyclic GMP) phosphodiesterase inhibitor 2-O-propoxyphenyl-8-azapurin-6-one, (M & B 22948; 20 microM). In addition, oxyHb did not reverse the inhibition with iloprost (1 nM) which inhibits platelet aggregation through stimulation of adenylate cyclase. 3. The inhibition of platelet aggregation by NO (7 +/- 1 microM) or NaNp (80 +/- 13 microM) was accompanied by a 13 fold increase in cyclic GMP levels occurring within 15 s of addition of these agents. In the continued presence of NO or NaNp, the reversing effect of oxyHb given 1 min after thrombin was associated with a pronounced decrease in cyclic GMP levels. 4. We conclude that the inhibition of platelet aggregation by activators of guanylate cyclase depends in the first few minutes on continuous stimulation of the enzyme in order to maintain intracellular concentrations of cyclic GMP, except when its breakdown is inhibited. 5. The addition of agents such as oxyHb after the inhibition of platelet aggregation offers another way of investigating the biochemical changes involved in maintaining platelets in an inactive state.
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Affiliation(s)
- D Salvemini
- William Harvey Research Institute, St Bartholomew's Hospital Medical College, Charterhouse Square, London
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21
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Javors MA, Liu M, Cuvelier BS, Bowden CL. Characterization of the effect of the adenosine agonist cyclohexyladenosine on platelet activating factor-induced increases in [Ca2+]i in human platelets in vitro. Cell Calcium 1990; 11:647-53. [PMID: 1965709 DOI: 10.1016/0143-4160(90)90019-q] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Previous studies have shown that adenosine agonists acting at A-2 receptors inhibit platelet aggregation. Since an increase in cytosolic Ca2+ concentration (delta [Ca2+]i) is closely associated with the time frame of platelet aggregation, we have examined the effect of adenosine receptor function on induced increases of [Ca2+]i by a potent platelet activator, platelet activating factor (PAF). We loaded washed platelets with Fura-2, then induced increases in [Ca2+]i with various concentrations of PAF, and then determined EC50 values (PAF concentration at half-maximal response) and values for maximal response of delta[Ca2+]i (max-delta[Ca2+]i). The EC50 for PAF-delta[Ca2+]i was 112 +/- 37 (SD) pM and the max-delta[Ca2+]i was 284 +/- 138 (SD) nM. Our results show that PAF-delta[Ca2+]i was inhibited in a non-competitive manner by the adenosine receptor agonist cyclohexyladenosine (CHA) with an IC50 of 14.9 microM. This inhibition was partially reversed by theophylline, an adenosine receptor antagonist, with an IC50 of 19 microM. Based on the results of these studies together with evidence from other research groups that platelets do not possess A-1 receptors, our results suggest that CHA inhibited PAF-delta[Ca2+]i in platelets through an activation of A-2 receptors.
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Affiliation(s)
- M A Javors
- Department of Psychiatry, University of Texas Health Science Center, San Antonio
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22
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Merlos M, Gomez L, Vericat M, Bartroli J, Garcia-rafanell J, Forn J. Structure-activity relationships in a series of xanthine derivatives with antibronchoconstrictory and bronchodilatory activities. Eur J Med Chem 1990; 25:653-8. [DOI: 10.1016/0223-5234(90)90130-u] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Abstract
This study examined whether the inhibitory actions of opioids in the guinea-pig ileum were influenced by agents which mimic or elevate intracellular cyclic adenosine 3',5'-monophosphate (cyclic AMP) levels. In longitudinal muscle-myenteric plexus preparations, the mu agonist, [D-Ala2,NMePhe4,Gly-ol5]enkephalin (DAGO) and the kappa agonist, dynorphin A-(1-13) depressed contractions of the longitudinal muscle evoked by electrical stimulation of myenteric neurons. Mean IC50 values were 19 and 2.8 nM for DAGO and dynorphin, respectively. Neither forskolin, cholera toxin nor dibutyryl cyclic AMP affected significantly the IC50s for the opioid agonists. The experiments suggest that mu and kappa agonists inhibit excitatory cholinergic transmission to the longitudinal muscle by intracellular effector mechanisms that do not involve cyclic AMP.
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Affiliation(s)
- S M Johnson
- Department of Physiology, Flinders University of South Australia, Bedford Park
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25
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Abstract
Cyclic AMP and the mechanism of vasodilation have been reviewed by first discussing the enzymes involved (adenyl cyclase, cyclic nucleotide phosphodiesterases, cyclic AMP-dependent protein kinase) and then agents that increase cAMP in smooth muscle. Two mechanisms of vasodilation are described: (i) effects on contractile proteins; (ii) effects on Ca2+ levels. Evidence for compartments of cAMP is also presented.
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Affiliation(s)
- K J Murray
- Department of Cellular Pharmacology, Smith Kline & French Research Ltd, Welwyn Herts, U.K
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26
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Cyr DG, Eales JG. T3 enhancement ofin vitro estradiol-17β secretion by oocytes of rainbow trout,Salmo gairdneri, is dependent on cAMP. Fish Physiol Biochem 1989; 6:255-259. [PMID: 24221556 DOI: 10.1007/bf01875028] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The cellular mechanism of action of 3,5,3'-triiodo-L-thyronine (T3) in enhancing SG-G100 gonadotropin-induced ovarian secretion of 17β-estradiol (E2) was studiedin vitro using oocyte follicular preparations of rainbow trout. The dependence of the T3 stimulatory action on the level of intracellular 3',5'-cyclic adenosine monophosphate (cAMP) was shown in experiments in which forskolin or dibutyryl cAMP enhanced E2 secretion. In the presence of partially purified salmon gonadotropin (SG-G100), T3 stimulation of E2 secretion was prevented by theophylline, suggesting that T3 may exert part of its stimulatory action by inhibiting phosphodiesterase.
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Affiliation(s)
- D G Cyr
- Department of Zoology, University of Manitoba, R3T 2N2, Winnipeg, Manitoba, Canada
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28
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Miot F, Keppens S, Erneux C, Wells JN, De Wulf H. Involvement of a plasma membrane phosphodiesterase in the negative control of cyclic AMP levels by vasopressin in rat hepatocytes. Biochem Pharmacol 1988; 37:3447-53. [PMID: 2844189 DOI: 10.1016/0006-2952(88)90695-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Vasopressin has been shown previously to lower the glucagon-induced increase of cyclic AMP levels in isolated rat hepatocytes by way of an enhanced phosphodiesterase (EC 3.1.4.17) activity. Five phosphodiesterase inhibitors were tested for their ability to prevent vasopressin from lowering cyclic AMP levels in intact hepatocytes and for their inhibitory effect in vitro on soluble and particulate phosphodiesterase activities partially purified from hepatocytes. Three soluble activities have been separated by DEAE-cellulose chromatography: a phosphodiesterase hydrolyzing both cyclic AMP and cyclic GMP, a form stimulated by cyclic GMP and a cyclic AMP-specific activity. The absence of any statistically significant correlation between the in vivo (in intact cells) and the in vitro (on isolated phosphodiesterases) potencies of the inhibitors does not support a role for the cytosolic phosphodiesterases in mediating the vasopressin-induced decrease in cyclic AMP levels. No statistically significant correlation was observed between the inhibition of the vasopressin effect on cyclic AMP accumulation and the inhibition of phosphodiesterase activity either associated with the native plasma membranes or solubilized from these membranes with 0.4 M NaCl. In contrast, a statistically significant correlation was observed between the degree of inhibition of the vasopressin effect in the intact cells and the degree of inhibition of the intrinsic phosphodiesterase still associated with the plasma membranes after high-salt treatment. These data indicate that a phosphodiesterase activity integral to the plasma membrane is very likely involved in the negative control of cyclic AMP levels by vasopressin.
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Affiliation(s)
- F Miot
- Afdeling Biochemie, Fakulteit der Geneeskunde, Katholieke Universiteit, Leuven, Belgium
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29
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Elias D, Rapoport M, Cohen IR, Shechter Y. Desensitization of the insulin receptor by antireceptor antibodies in vivo is blocked by treatment of mice with beta-adrenergic agonists. J Clin Invest 1988; 81:1979-85. [PMID: 3290258 PMCID: PMC442651 DOI: 10.1172/jci113546] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
In previous studies we reported that immunization of mice with ungulate insulins induced the development of antiinsulin antibodies, which include an idiotype that appeared to recognize the part of the insulin molecule recognized by the hormone receptor. The antiinsulin antibodies of this idiotype were replaced spontaneously by antiidiotypic antibodies. The antiidiotypic antibodies, which persisted for about 14 d, mimicked insulin and functioned as antibodies to the insulin receptor. They induced down regulation, desensitization and refractoriness of the insulin receptor and disturbances in glucose homeostasis in vivo (Shechter, Y., D. Elias, R. Maron, and I.R. Cohen., 1984; Elias, D., R. Maron, I.R. Cohen, and Y. Shechter. 1984, J. Biol. Chem. 259: 6411-6419). We now report that effects of the antiidiotypic antibodies on the insulin receptor effector system can be modified pharmacologically. Administration of the beta-adrenergic agonist isoproterenol during the period of insulin resistance (days 26-40 after primary immunization), largely restored fat cell responsiveness to insulin, and eliminated the appearance of fasting hyperglycemia. This restoration appeared to be caused by inhibition of both insulin receptor desensitization and refractoriness. In contrast, down regulation of insulin receptors was not reversed by isoproterenol treatment in vivo. The effects of treatment with isoproterenol persisted for 2-4 d after termination of treatment. The beta-antagonist, propranolol and more so, the beta 1a-antagonist metoprolol, specifically blocked the effect of isoproterenol at a molar ratio of 3-10:1. Oral administration of the cAMP phosphodiesterase inhibitor, aminophylline, was also effective in inhibiting the development of desensitization in fat cells. These results indicate that treatment with beta 1-adrenergic agonists in vivo, or other agents that elevate cellular cAMP levels, can inhibit the development of the "postbinding" defects induced by insulin-mimicking, antireceptor antibodies. These observations have both basic and clinical implications.
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Affiliation(s)
- D Elias
- Department of Hormone Research, Weizmann Institute of Science, Rehovot, Israel
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30
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Zhang Y, Lin JX, Vilcek J. Synthesis of interleukin 6 (interferon-beta 2/B cell stimulatory factor 2) in human fibroblasts is triggered by an increase in intracellular cyclic AMP. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(18)68768-x] [Citation(s) in RCA: 167] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Abstract
The possible mediatory role of cAMP in the induction of oocyte maturation by luteinizing hormone (LH) is not yet clear since evidence for both inhibitory and stimulatory actions of the nucleotide on the oocyte has been provided. To elucidate the role of cAMP in regulation of oocyte meiosis we tried in the present study to dissociate between the inhibitory and stimulatory action of this nucleotide on oocyte maturation. To induce maturation, oocytes enclosed by their follicles were transiently exposed to either dibutyryl cAMP (dbcAMP) or to the phosphodiesterase inhibitor methylisobutylxanthine (MIX). Inhibition of maturation was obtained by the addition of the above agents to either follicle-enclosed oocytes incubated in the presence of LH or isolated cumulus-free oocytes that mature spontaneously in vitro. We found that inhibition of oocyte maturation is obtained by a relatively low dose of either dbcAMP or MIX while higher concentrations of these agents are required to induce oocyte maturation. Coupling of the oocyte to the cumulus cells, as expressed by the fraction of labeled uridine transferred from the cumulus cells to the oocyte following exposure of the follicle-enclosed cumulus-oocyte complex to MIX, was also determined. We found that uncoupling of the oocyte from the cumulus cells corresponded with the induction, but not inhibition of oocyte maturation, both by its concentration dependence and time-course. We suggest that cAMP has a dual role in regulation of oocyte maturation. Lower levels of the nucleotide act to maintain meiotic arrest, while elevated levels of cAMP mediate LH action to induce meiosis resumption.
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Affiliation(s)
- N Dekel
- Department of Hormone Research, Weizmann Institute of Science, Rehovot, Israel
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32
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Wun WS, Berkowitz AS, Preslock JP. Differences in the cyclic nucleotide mediation of luteinizing hormone-releasing hormone action on the rat and hamster anterior pituitary gland. Mol Cell Endocrinol 1988; 55:173-82. [PMID: 2451626 DOI: 10.1016/0303-7207(88)90132-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
A continuous flow superfusion system which was previously developed in our laboratory was utilized to study the modulation of LH and FSH release by cyclic nucleotides and LHRH from anterior pituitary glands (APG) obtained from rats or hamsters. There was a transient increase in LH and FSH secretion from superfused rat APG in response to superfusion with 1 X 10(-3) M 1-methyl-3-isobutyl-xanthine (MIX), while 1 X 10(-4) MIX M had no effect. Furthermore, a dose of 5 X 10(-5) M MIX did not potentiate the gonadotrophin-releasing effect of 1 X 10(-10) M LHRH. Neither 1 X 10(-3) M 8-Br-cAMP nor 1 X 10(-3) M 8-Br-cGMP mimicked the gonadotrophin-releasing effects of 1 X 10(-9) M LHRH. In the experiments utilizing hamster APG, FSH release gradually increased during superfusion with 1 X 10(-3) M MIX or 1 X 10(-4) M MIX, while LH release was transient but significantly increased in response to superfusion with both doses of MIX. A dose of 5 X 10(-5) M MIX potentiated the effect of a low dose of LHRH (1 X 10(-10) M) upon both LH and FSH secretion. 1 X 10(-3) M 8-Br-cAMP mimicked the effect of LHRH upon LH and FSH released from superfused hamster APG, while 1 X 10(-3) M 8-Br-cGMP was inhibitory. These results suggest that cyclic nucleotides are involved in the mediation of the LHRH-induced release of gonadotropins from the anterior pituitary gland of the hamster, but do not mediate the LHRH-induced release of gonadotropins from the rat anterior pituitary gland.
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Affiliation(s)
- W S Wun
- Department of Obstetrics and Gynecology, Tulane University School of Medicine, New Orleans, LA 70112
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33
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Abstract
The role of the calcium messenger system in the regulation of ion absorption across the teleost intestine was studied using pharmacological intervention. Radiochloride transport was independent of external Ca2+ over the range 10 microM to 2.5 mM. Treatment with the Ca2+ ionophore A23187 (to hyperpolarization of the apical membrane potential of intestinal epithelial cells. The Ca2+-calmodulin antagonists trifluoperazine (TFP) and calmidazolium (R24571) produced opposite effects, i.e., stimulation of Cl- absorption and cellular depolarization. Treatment with TFP or R24571 will block or override the inhibitory action of A23187. These data suggest a regulatory role for Ca2+ in the control of intestinal NaCl absorption and mediation via calmodulin.
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Affiliation(s)
- C A Loretz
- Department of Biological Sciences, State University of New York at Buffalo 14260
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34
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Pinet F, Mizrahi J, Laboulandine I, Menard J, Corvol P. Regulation of prorenin secretion in cultured human transfected juxtaglomerular cells. J Clin Invest 1987; 80:724-31. [PMID: 2957392 PMCID: PMC442296 DOI: 10.1172/jci113127] [Citation(s) in RCA: 34] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The regulation of renin secretion was studied in continuous culture of human juxtaglomerular cells (JGC), which provided a permanent source of human renin production (Pinet, F., M. T. Corvol, F. Dench, J. Bourguignon, J. Feunteun, J. Ménard, and P. Corvol, 1985, Proc. Natl. Acad. Sci. USA, 82:8503-8507). 95% of the renin species secreted was prorenin, and therefore this study concerned primarily prorenin secretion. Renin production was stable, since the cells had been maintained in culture for more than two years. In culture, these human cells formed colonies of smooth musclelike cells, and electron microscopy showed the presence of cytoskeleton structures including myofibrils and attachment bodies. This human model was used to investigate the control of prorenin secretion in vitro at cellular level. Various pharmacological agents known to stimulate or inhibit renin secretion were tested in the cell cultures. The variations in prorenin secretion were measured in the supernatant. Forskolin, an independent receptor activator of adenylate cyclase, stimulated prorenin secretion in a dose-dependent manner and this stimulation was mediated by 3',5' cyclic-AMP (cAMP). Angiotensin II (AII) was found to inhibit prorenin secretion directly in a dose-dependent manner and atrial natriuretic factor (ANF), whose effects on human JGC were characterized for the first time, was also shown to exert such inhibition. When the effects of this inhibition by AII and ANF were tested on forskolin-mediated stimulation of prorenin secretion, the latter was inhibited and no change occurred in cAMP release. When JGC were treated with histamine, bradykinin, or one or two bradykinin analogues, the responses suggested that in these cells, H2-histamine receptors and kinin receptors are dependent on adenylate cyclase. One peptide, substance P, had an inhibitory effect on prorenin secretion but it was less important than AII and ANF. The present results demonstrate that the adenylate cyclase system of human JGC remains intact during culture and supports the hypothesis that cAMP is the second messenger and Cai2+, the final messenger involved in renin secretion. The cell system used here permits the evaluation of cellular responses and intracellular events in granulated cells in a human model.
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Abstract
The site and mechanism of action of epidermal growth factor (EGF) on acid secretion by rat isolated parietal cells were investigated by using the intracellular accumulation of the weak base aminopyrine as an index of secretory activity. When parietal cells were stimulated with histamine (0.5 mM), the concentration of EGF required for half-maximal inhibition of acid secretion was 19 nM, with a maximally effective concentration of EGF producing 38% inhibition of secretory activity. EGF did not inhibit secretion stimulated by 0.1 mM-carbachol, or by 30 microM-, 56 microM-, 100 microM- or 1000 microM-dibutyryl cyclic AMP, low concentrations of which produced a secretory response comparable with that obtained with 0.5 mM-histamine. Addition of 0.1 mM-3-isobutyl-1-methylxanthine (IBMX) substantially increased aminopyrine accumulation in the presence of 0.5 mM-histamine. The inhibitory action of EGF on histamine-stimulated secretion was blocked by 0.1 mM-IBMX, even if low concentrations of histamine were used to generate aminopyrine accumulation ratios similar to those obtained with 0.5 mM-histamine alone. The cyclo-oxygenase inhibitor flurbiprofen (1-100 microM) and the cyclo-oxygenase and lipoxygenase inhibitor nordihydroguaiaretic acid (10-100 microM) did not affect the inhibitory action of EGF. The pattern of inhibition of secretion produced by the activator of Ca2+-sensitive phospholipid-dependent protein kinase, 12-O-tetradecanoylphorbol 13-acetate, was markedly different from that produced by EGF. In conclusion, a major site of the action of EGF on acid secretion in the intact stomach is probably a decrease in the stimulatory effect of histamine by a mechanism which does not involve Ca2+-sensitive phospholipid-dependent protein kinase or the production of prostaglandins, but which might involve enhancement of cyclic AMP phosphodiesterase activity.
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Affiliation(s)
- G P Shaw
- Department of Molecular Sciences, Aston University, Birmingham, U.K
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Poueymirou WT, Schultz RM. Differential effects of activators of cAMP-dependent protein kinase and protein kinase C on cleavage of one-cell mouse embryos and protein synthesis and phosphorylation in one- and two-cell embryos. Dev Biol 1987; 121:489-98. [PMID: 3034703 DOI: 10.1016/0012-1606(87)90185-0] [Citation(s) in RCA: 61] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Membrane-permeable cAMP analogs or elevation of intracellular cAMP by cyclic nucleotide phosphodiesterase (PDE) inhibitors activates cAMP-dependent protein kinase. Biologically active phorbol esters or diacylglycerol activate the calcium-, phospholipid-dependent protein kinase, protein kinase C (PK-C). We report that membrane-permeable cAMP analogs, PDE inhibitors, biologically active phorbol esters, or a synthetic diacylglycerol inhibited cleavage of 1-cell mouse embryos to the 2-cell stage. The cAMP analogs and PDE inhibitors were effective only when added prior to S of the first cell cycle, whereas PK-C activators inhibited cleavage when added up until late G2/M. The PDE inhibitor Ro 20 1724/1 inhibited both DNA and protein synthesis in 1-cell embryos, whereas the phorbol ester, 12-O-tetradecanoyl-phorbol-13 acetate, or alpha-amanitin did not. In addition, 1-cell embryos prevented from cleaving by PDE inhibitors did not show specific changes in the pattern of protein phosphorylation associated with the 2-cell embryo, whereas such changes occurred in 1-cell embryos inhibited from cleaving with PK-C activators. Transcription in the 2-cell embryo results in the synthesis of a specific set of proteins, which is inhibited by alpha-amanitin. Although treatment of 1-cell embryos with aphidicolin or PK-C activators during G1 did not inhibit the synthesis of these proteins, treatment with cAMP analogs or PDE inhibitors during G1 inhibited the appearance of these proteins. These results are discussed in terms of how the synthesis of transcription-dependent proteins in the 2-cell embryo may be regulated by protein phosphorylation.
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Franz DN, Peterson RG, Madsen PW, Sangdee C. Enhancement of central transmission to sympathetic preganglionic neurons by phosphodiesterase inhibitors and its prevention by clonidine. J Auton Nerv Syst 1987; 19:199-209. [PMID: 3040847 DOI: 10.1016/0165-1838(87)90066-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The effects of 3 phosphodiesterase inhibitors, aminophylline, isobutylmethylxanthine (IBMX), and RO 20-1724, were tested on descending intraspinal and spinal reflex transmission to sympathetic preganglionic neurons in unanesthetized spinal cats. Sympathetic discharges, recorded from upper thoracic preganglionic white rami, were evoked by stimulation (0.1 Hz) of descending excitatory pathways in the cervical dorsolateral funiculus (intraspinal) or of adjacent intercostal nerves (spinal reflex). Each phosphodiesterase rapidly and markedly enhanced transmission through intraspinal pathways but only slowly and modestly enhanced transmission through spinal reflex pathways. Pretreatment with a methyltyrosine-reserpine combination, chlorpromazine, or prazosin markedly restricted the enhancement of intraspinal transmission by IBMX to levels typically produced on spinal reflex pathways. Clonidine markedly depressed transmission through both pathways and prevented enhancement by the phosphodiesterase inhibitors. Yohimbine or tolazoline antagonized the depressant effects of clonidine and restored the ability of the phosphodiesterase inhibitors to enhance transmission. Somatic spinal reflexes were not affected by the phosphodiesterase inhibitors. The results suggest that descending norepinephrine pathways to sympathetic preganglionic neurons activate adenylate cyclase to generate cyclic AMP which increases neuronal excitability, possibly by phosphorylating membrane proteins. Clonidine appears to depress neuronal excitability by inhibiting adenylate cyclase through activation of alpha 2-adrenergic receptors.
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DeManno DA, Goetz FW. The effects of forskolin, cAMP, and cyanoketone on steroid-induced meiotic maturation of yellow perch (Perca flavescens) oocytes in vitro. Gen Comp Endocrinol 1987; 66:233-43. [PMID: 3034715 DOI: 10.1016/0016-6480(87)90272-3] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Intact yellow perch (Perca flavescens) follicles stimulated by 17 alpha, 20 beta-dihydroxy-4-pregnen-3-one (17 alpha, 20 beta-PG) to undergo germinal vesicle breakdown (GVBD) in vitro were incubated with several agents which have been shown to increase cellular cAMP levels. Two phosphodiesterase inhibitors, SQ20,006 and isobutyl-methyl-xanthine, blocked GVBD at 1.0 mM. At lower levels (0.5, 0.1 mM) there was a dose-response effect and SQ20,006 was more inhibitory. Forskolin at 1.0-20.0 microM blocked steroid-induced GVBD, but levels of 0.1 microM or less were noninhibitory. In time-course experiments, significant inhibition of GVBD was observed when SQ20,006 (1.0 mM) was added within 6 hr after steroid stimulation or forskolin (10.0 microM) was added within 12 hr. When SQ20,006 was administered in 6-hr pulses and then removed, inhibition was observed only when the steroid was given as a 1-hr prepulse which was removed at the start of the incubation period. In this case, GVBD was blocked if the SQ20,006 pulse was given before 18 hr. At 10.0 mM, cAMP completely inhibited GVBD but was noninhibitory at lower levels. However, lower levels of cAMP (1.0, 0.5 mM) and forskolin (0.1 microM) were inhibitory if the follicles were also incubated with 1.0 microgram/ml of cyanoketone, an inhibitor of steroidogenesis. These results indicate that in vitro, increases in cAMP are inhibitory to steroid-induced meiotic maturation but may stimulate steroidogenesis in the follicle wall as well. Furthermore, in vitro steroid-stimulated maturation can be inhibited by increased cAMP for a relatively long time, following steroid treatment.
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Nwoga J. Concerning stimulation by high external potassium and calcium injection of the ouabain-insensitive sodium efflux in barnacle muscle fibers. Comp Biochem Physiol A Comp Physiol 1987; 86:733-7. [PMID: 2882905 DOI: 10.1016/0300-9629(87)90633-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The behavior of the ouabain-insensitive Na efflux in barnacle muscle fibers toward external high K and injection of Ca2+ has been further investigated. Raising Ke to 100 mM after the injection of 0.25 M or 0.1 M GTPNa2 results in a biphasic stimulatory response: the initial response is prompt in onset and small but transitory, whereas the delayed response is large and sustained. This second stimulatory phase is reduced markedly by injecting EGTA but not by PKI. Raising Ke to 100 mM in the presence of the 2 xanthine derivatives, viz. PMX and IAX, leads to a sustained stimulatory response of the ouabain-insensitive Na efflux which is halved by injecting PKI but unaffected by injecting EGTA. Injection of 0.1 M or 0.5 M CaCl2 in the presence of PMX and IAX leads to a sustained stimulatory response, which is almost completely abolished by injecting PKI but unaffected by injecting EGTA. These results confirm the earlier finding that the response of the ouabain-insensitive Na efflux to high Ke in fibers preinjected with GTPNa2 is biphasic and that the delayed second stimulatory phase is sustained rather than transitory. The ability of injected EGTA to only partially reverse the delayed response suggests that a fall in myoplasmic pCa is not the sole factor governing the kinetic picture. The experiments with PMX and IAX strongly suggest that cAMP is involved in the termination of the Ca2+ message.
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Boudreaux MK, Dodds WJ, Slauson DO, Catalfamo JL. Impaired cAMP metabolism associated with abnormal function of thrombopathic canine platelets. Biochem Biophys Res Commun 1986; 140:595-601. [PMID: 2430569 DOI: 10.1016/0006-291x(86)90773-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The effects of forskolin and 1-Methyl-3-isobutyl-xanthine on thrombopathic platelet function and cyclic AMP accumulation were examined. The concentration of forskolin required to inhibit gamma-thrombin- induced platelet aggregation and secretion by 50% was significantly lower for thrombopathic than for normal platelets. This inhibition was accompanied by a marked elevation of cyclic AMP. 1-Methyl-3-isobutyl-xanthine, alone or in combination with forskolin, augmented both the cyclic AMP accumulation and the inhibition of platelet function. These results demonstrate that cyclic AMP metabolism is abnormal in thrombopathic platelets and imply that cyclic AMP-phosphodiesterase activity is impaired.
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Jalabert B, Finet B. Regulation of oocyte maturation in the rainbow trout,Salmo gairdneri: role of cyclic AMP in the mechanism of action of the maturation inducing steroid (MIS), 17α-hydroxy, 20β-dihydroprogesterone. Fish Physiol Biochem 1986; 2:65-74. [PMID: 24233168 DOI: 10.1007/bf02264074] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
In fish, oocyte maturation (resumption of meiosis after completion of vitellogenesis and before ovulation) is triggered by maturation inducing steroids (MIS) which generally appear to be secreted in the ovary in response to stimulation by a pituitary maturational gonadotropin. Converging data from different laboratories show that 17α-hydroxy, 20β-dihydroprogesterone (17α, 20β-OH-P) is the principal MIS in salmonoids; but clear identification remains to be done in other taxonomic groups.The experiments reported here in the rainbow troutSalmo gairdneri examine the possible involvement of oocyte cAMP on the mechanism of MIS action. The action of 17α, 20β-OH-P, on germinal vesicle breakdown (GVBD) in oocytes incubatedin vitro within the follicle, was inhibited by various substances expected to elevate the intraoocyte concentrations of cAMP: cAMP (≥ 1 mM) or dibutyril cAMP (≥ 2 mM), phosphodiesterase inhibitors such as theophylline (≥ 0.2 mM) or 3-isobutyl-1 methylxanthine (IBMX ≥ 0.1 mM), adenylate cyclase activators such as cholera toxin (> 100 nM) or forskolin (≥ 0.03 mM). In fact, the combined action of IBMX (1 mM) and forskolin (0.01 or 0.05 mM)in vitro was to promote accumulation of intraoocyte cAMP within 1 to 5 hours. Oocyte cAMP concentrations exhibited a large variability between different females, depending on the stage of oocyte development; a significant positive correlation between oocyte cAMP concentration and the follicular weight, and a significant negative correlation between oocyte cAMP concentration and the median efficient dose of 17α, 20β-OH-P for induction of GVBD, were observed. Finally, when intrafollicular oocytes were incubatedin vitro, the addition of a maturation-inducing concentration of 17α, 20β-OH-P (3×10(-6)M) induced a significant decrease of oocyte cAMP within the first 10 hours of incubation. These results show that cAMP appears to play a central role in the regulation of oocyte sensitivity to 17α, 20β-OH-P and in the intraoocyte mechanisms leading to GVBD in trout.These data are discussed together with the few indications available in fish concerning the mechanism of MIS action which can be compared to some extent with the amphibian model.
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Affiliation(s)
- B Jalabert
- Institut National de la Recherche Agronomique, Laboratoire de Physiologie des Poissons, Campus de Beaulieu, 35042, Rennes Cédex, France
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Abstract
The effect of aminophylline on renin release from human chorion was investigated by perfusing the tissue with various concentrations of the drug. Buffer containing aminophylline (2 X 10(-6) mol/l) doubled the rate of active and total renin secretion, but a more concentrated solution (10(-5) mol/l) released proportionately less active and total renin although the result was statistically significant. Renin secretion was not altered by aminophylline (5 X 10(-5) mol/l). The pattern of renin release was modulated by concentrations of aminophylline which were at least a 100-fold lower than those required to inhibit cyclic adenosine 3',5'-monophosphate phosphodiesterase. However, as the methylxanthines are potent adenosine receptor antagonists, we suggest that in the human chorion adenosine is a mediator of renin release.
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Gabbay RA, Lardy HA. Methylisobutylxanthine blocks insulin antagonism of cAMP-stimulated glycogenolysis at a site distinct from phosphodiesterase. Evidence favoring an insulin-insensitive calcium release mechanism. J Biol Chem 1986. [DOI: 10.1016/s0021-9258(17)35613-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Abstract
The possible roles of follicular cyclooxygenase and cAMP in the control of in vitro spontaneous brook trout (Salvelinus fontinalis) ovulation were investigated. Brook trout oocytes that had undergone germinal vesicle breakdown and follicular separation in vivo, were incubated in vitro in the presence of indomethacin. At 3 or 30 microM, indomethacin significantly reduced the levels of PGF and PGE (measured by radioimmunoassay) in the incubation medium but did not inhibit spontaneous ovulation in vitro. Follicular cAMP levels were measured by a competitive protein binding assay, prior to and during spontaneous ovulation. cAMP levels were approximately 3.2 pmol/mg protein prior to incubation and did not fluctuate significantly from this value throughout the 24-hr incubation period. The phosphodiesterase inhibitor, 3-isobutyl-l-methyl-xanthine, significantly increased follicular cAMP levels at 1.0 and 0.1 mM. The combined results suggest that cyclooxygenase metabolites or a decrease in cAMP are not involved in the control of spontaneous brook trout ovulation in vitro. The in vitro effects of primaquine, a putative phospholipase mediator, were also investigated. At lower concentrations (0.1-0.5 mM), primaquine significantly enhanced ovulation above that observed in spontaneous controls. However, at 1.0 mM, primaquine inhibited spontaneous ovulation. Indomethacin at 3 or 30 microM did not block the stimulatory effect of primaquine observed at lower concentrations, indicating that cyclooxygenase metabolites are not involved in the stimulatory effect of primaquine on ovulation.
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Honnor RC, Dhillon GS, Londos C. cAMP-dependent protein kinase and lipolysis in rat adipocytes. I. Cell preparation, manipulation, and predictability in behavior. J Biol Chem 1985. [DOI: 10.1016/s0021-9258(18)95711-x] [Citation(s) in RCA: 224] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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Meller VH, Aucoin RR, Tobe SS, Feyereisen R. Evidence for an inhibitory role of cyclic AMP in the control of juvenile hormone biosynthesis by cockroach corpora allata. Mol Cell Endocrinol 1985; 43:155-63. [PMID: 2416608 DOI: 10.1016/0303-7207(85)90079-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
High levels of cyclic AMP were found in the corpora allata of adult female Diploptera punctata. The adenylate cyclase activator forskolin caused a rapid, reversible and dose-dependent accumulation of cAMP in the corpora allata in vitro. The sensitivity of the corpora allata to forskolin was low when juvenile hormone (JH) synthetic activity was high, and vice versa. Incubation of corpora allata with compounds which cause or mimic elevated intracellular cAMP levels (forskolin, 3-isobutyl-1-methylxanthine, 8-bromo-cAMP) led to a rapid and dose-dependent inhibition of juvenile hormone synthesis. Glands from day 5 virgin females were more sensitive to forskolin than glands from mated females of the same age. The results suggest that a cAMP second messenger system may be responsible for the intracellular transduction of inhibitory signals to the corpora allata of D. punctata.
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Wong EH, Ooi SO. Methylxanthine and non-xanthine phosphodiesterase inhibitors. Their effects on adenosine uptake and the low Km cyclic AMP phosphodiesterase in intact rat adipocyte. Biochem Pharmacol 1985; 34:2891-6. [PMID: 2411270 DOI: 10.1016/0006-2952(85)90012-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The effects of methylxanthines and non-xanthine phosphodiesterase-inhibitors on the low Km cyclic AMP phosphodiesterase of intact rat adipocytes were studied. Methylxanthines and papaverine stimulated rather than inhibited the enzyme when intact adipocytes were incubated in their presence. The effect of papaverine was not abolished by adenosine deaminase and was enhanced by adenosine. On the other hand, the effect of xanthine inhibitors and adenosine do not enhance each other. The difference in behaviour of these inhibitors could not be explained by their effects on adenosine uptake at the concentrations studied. Both agents inhibited adenosine uptake when measured after 15 sec and 10 min, with methylisobutylxanthine (MIX) having a greater inhibitory effect than papaverine only if uptake was measured after 15 sec. Effects similar to that of adenosine with the inhibitors on phosphodiesterase were obtained with insulin, which has been shown to act through a similar or related mechanism to that of adenosine. This was not the case with lipolytic agents whose effects were not potentiated by either MIX or papaverine. Under certain conditions the degree of stimulation of the enzyme was in fact decreased. Thus lipolytic and antilipolytic agents probably stimulated phosphodiesterase through distinct mechanisms.
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Henquin JC. The interplay between cyclic AMP and ions in the stimulus-secretion coupling in pancreatic B-cells. Arch Int Physiol Biochim 1985; 93:37-48. [PMID: 2409943 DOI: 10.3109/13813458509104514] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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McCabe J, Scholfield CN. Adenosine-induced depression of synaptic transmission in the isolated olfactory cortex: receptor identification. Pflugers Arch 1985; 403:141-5. [PMID: 2984640 DOI: 10.1007/BF00584091] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
We have investigated the type of purine receptor in the guinea-pig olfactory cortex, using pial surfaces slices maintained in vitro. Adenosine (0.1 to 100 mumol/l) bath applied in the presence of the uptake inhibitor nitrobenzylthioinosine, depressed the evoked potentials in a dose related fashion. Synthetic and uptake resistant adenosine analogues had the same effect as adenosine and the order of potency of these was: 5'-N-ethylcarboxamide adenosine greater than L-N6-phenylisopropyl adenosine (L-PIA) = N6-cyclohexyladenosine = 2-chloroadenosine greater than adenosine greater than D-N6-phenylisopropyladenosine (D-PIA). The D-stereoisomer of PIA was 45 times less potent than L-PIA. The methylxanthine compounds 8-phenyltheophylline (3 mumol/l) and 3-isobutyl-1-methylxanthine (50 mumol/l) antagonised the depression produced by L-PIA. Rolipram, a phosphodiesterase inhibitor, in concentrations up to 100 mumol/l had no effect on the evoked potentials or on adenosine action. Forskolin, a cAMP stimulant, slightly increased the amplitude of the evoked potential, and partly reversed the depressant effect of adenosine. Noradrenaline had no effect either alone or in the presence of adenosine. The results of these experiments indicate the existence of A1 subtype adenosine receptors in the guinea pig olfactory cortex probably linked to a depression of intracellular cAMP.
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Bittar EE, Chambers G. The modulatory action of 5-hydroxytryptamine on sodium efflux: the barnacle muscle fibre as a model system. Comp Biochem Physiol C Comp Pharmacol Toxicol 1985; 80:421-9. [PMID: 2861030 DOI: 10.1016/0742-8413(85)90079-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
A study has been made of the action of 5-hydroxytryptamine (5-HT) on the radio-sodium efflux from single barnacle muscle fibres. (i) Stimulation of the Na efflux by external application of 5-HT is seen in both unpoisoned and ouabain-poisoned fibres. (ii) Concentrations of 5-HT as low as 10(-9)M are effective. (iii) Characteristically, the response to 5-HT is prompt in onset, reaches a peak within 20 min and then decays rather rapidly. Fibres from certain barnacle specimens are sometimes unresponsive to 5-HT. Such fibres, however, can be rendered responsive by preinjecting into them the non-hydrolysable GTP analogue, Gpp(NH)p. The response of the ouabain-insensitive Na efflux to 5-HT depends on external Ca2+ and, to a certain extent, on external Na+. (i) The response to 5-HT is unaffected by prior external application of Ca2+ antagonists, viz. verapamil, Cd2+ and WB-4101. (ii) The calmodulin antagonist, trifluoperazine (10(-5)M), completely abolishes the response to 5-HT, even in fibres preinjected with Gpp(NH)p. (iii) Diphenylhydantoin is less effective than trifluoperazine (TFP). Whereas the receptor antagonist methysergide is ineffective, cyproheptadine is very effective. (i) Prior application of the phosphodiesterase inhibitor 1-propyl-3-methyl-7-(5-hydroxyhexyl)-xanthine (PMX) or the inhibitor 1-isoamyl-3-isobutyl-xanthine (IAX) augments the size of the response to 5-HT, but fails to stop the response from decaying. (ii) Augmentation of the response to 5-HT by IAX is seen despite the presence of 10(-5) M-TFP. Prior injection of Mg2+ or protein kinase inhibitor (PKI) leads to abolition or reduction of the response to 5-HT. These results demonstrate that barnacle fibres are a useful preparation for investigation the natriferic action of 5-HT. They also support the view that the response to 5-HT involves a receptor-adenylate cyclase complex and is the result of activation by newly formed cAMP of cAMP-dependent protein kinase.
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