The Experts below are selected from a list of 264 Experts worldwide ranked by ideXlab platform

Yukio Kimura - One of the best experts on this subject based on the ideXlab platform.

  • phosphorylation of the vasodilator stimulated phosphoprotein vasp by the anti platelet drug cilostazol in platelets
    Platelets, 2003
    Co-Authors: Toshiki Sudo, Yukio Kimura
    Abstract:

    Vasodilator-stimulated phosphoprotein (VASP) is a regulator of actin dynamics in platelets and a common substrate of both cAMP- and cGMP-dependent protein kinases (PKA and PKG). Elevations of the cAMP and cGMP concentration have been shown to inhibit platelet aggregation. Intracellular levels of cAMP and cGMP are regulated by the synthesizing system of Adenylate Cyclases, and hydrolysis by cyclic nucleotide phosphodiesterases (PDEs). The present study examined the effect of the anti-platelet drug, cilostazol, which inhibits PDE3 activity, on VASP phosphorylation in platelets. VASP phosphorylation was examined by immunoblotting with an anti-VASP antibody, M4, and an anti-phospho-VASP antibody, 16C2. Cilostazol phosphorylated VASP at both Ser157 and Ser239 in a concentration-dependent manner, but EHNA (PDE2 inhibitor), dipyridamole and zaprinast (PDE5 inhibitors) did not. Forskolin (Adenylate Cyclase Activator) and sodium nitroprusside (SNP, NO donor) resulted in the VASP phosphorylation, with increase in t...

  • Phosphorylation of the vasodilator-stimulated phosphoprotein (VASP) by the anti-platelet drug, cilostazol, in platelets.
    Platelets, 2003
    Co-Authors: Toshiki Sudo, Hideki Ito, Yukio Kimura
    Abstract:

    Vasodilator-stimulated phosphoprotein (VASP) is a regulator of actin dynamics in platelets and a common substrate of both cAMP- and cGMP-dependent protein kinases (PKA and PKG). Elevations of the cAMP and cGMP concentration have been shown to inhibit platelet aggregation. Intracellular levels of cAMP and cGMP are regulated by the synthesizing system of Adenylate Cyclases, and hydrolysis by cyclic nucleotide phosphodiesterases (PDEs). The present study examined the effect of the anti-platelet drug, cilostazol, which inhibits PDE3 activity, on VASP phosphorylation in platelets. VASP phosphorylation was examined by immunoblotting with an anti-VASP antibody, M4, and an anti-phospho-VASP antibody, 16C2. Cilostazol phosphorylated VASP at both Ser157 and Ser239 in a concentration-dependent manner, but EHNA (PDE2 inhibitor), dipyridamole and zaprinast (PDE5 inhibitors) did not. Forskolin (Adenylate Cyclase Activator) and sodium nitroprusside (SNP, NO donor) resulted in the VASP phosphorylation, with increase in the cAMP and cGMP level, respectively. Cilostazol increased cAMP, but not cGMP levels, in platelets. EHNA, zaprinast and dipyridamole, had no effect on cAMP and cGMP levels. The PKA/PKG inhibitor, H-89, inhibited VASP phosphorylation by cilostazol. These results demonstrated that cilostazol phosphorylates VASP through the PDE3 inhibition, increase of cAMP level, and PKA activation in platelets.

Toshiki Sudo - One of the best experts on this subject based on the ideXlab platform.

  • Effects of the cAMP-elevating agents cilostamide, cilostazol and forskolin on the phosphorylation of Akt and GSK-3β in platelets
    Thrombosis and Haemostasis, 2009
    Co-Authors: Hideki Hayashi, Toshiki Sudo
    Abstract:

    SummaryElevating intracellular cAMP has been shown to inhibit platelet function. cAMP interferes with platelet-activating signals which lead to aggregation inhibition, but the precise mechanism is unclear.The present study examined if cAMP-elevating agents inhibited phosphatidylinositol 3-kinase (PI3-kinase) signaling in rat platelets by immunoblotting. Akt is one of the key molecules downstream of PI3K, and is phosphorylated by collagen stimulation. The phosphodiesterase-3 (PDE3) inhibitors cilostamide and cilostazol, and the Adenylate Cyclase Activator forskolin, inhibited collagen-induced Akt phosphorylation at Ser473.The inhibitory effects of these cAMP-elevating agents on Akt phosphorylation were unchanged in the presence of the PKA (cyclic AMP-dependent protein kinase) inhibitor H-89. These effects were consistent with inhibition of platelet aggregation. It is known that inhibition of Akt phosphorylation leads to inhibition of phosphorylation of glycogen synthase kinase 3-beta (GSK-3β), which is an effector of Akt, but cAMP-elevating agents stimulated GSK-3βphosphorylation at Ser9.The PKA inhibitor H-89 attenuated GSK-3βphosphorylation.The cAMP-elevating agents cilostamide, cilostazol and forskolin did not directly affect the enzyme activity of PI3-kinase.These results suggested that cAMP-elevating agents have two effects on PI3K signalling: inhibition of Akt phosphorylation independent of PKA; and stimulation of GSK-3β phosphorylation dependent on PKA. Our results provide new insights into the inhibitory effect of cAMPelevating agents on platelet function.

  • phosphorylation of the vasodilator stimulated phosphoprotein vasp by the anti platelet drug cilostazol in platelets
    Platelets, 2003
    Co-Authors: Toshiki Sudo, Yukio Kimura
    Abstract:

    Vasodilator-stimulated phosphoprotein (VASP) is a regulator of actin dynamics in platelets and a common substrate of both cAMP- and cGMP-dependent protein kinases (PKA and PKG). Elevations of the cAMP and cGMP concentration have been shown to inhibit platelet aggregation. Intracellular levels of cAMP and cGMP are regulated by the synthesizing system of Adenylate Cyclases, and hydrolysis by cyclic nucleotide phosphodiesterases (PDEs). The present study examined the effect of the anti-platelet drug, cilostazol, which inhibits PDE3 activity, on VASP phosphorylation in platelets. VASP phosphorylation was examined by immunoblotting with an anti-VASP antibody, M4, and an anti-phospho-VASP antibody, 16C2. Cilostazol phosphorylated VASP at both Ser157 and Ser239 in a concentration-dependent manner, but EHNA (PDE2 inhibitor), dipyridamole and zaprinast (PDE5 inhibitors) did not. Forskolin (Adenylate Cyclase Activator) and sodium nitroprusside (SNP, NO donor) resulted in the VASP phosphorylation, with increase in t...

  • Phosphorylation of the vasodilator-stimulated phosphoprotein (VASP) by the anti-platelet drug, cilostazol, in platelets.
    Platelets, 2003
    Co-Authors: Toshiki Sudo, Hideki Ito, Yukio Kimura
    Abstract:

    Vasodilator-stimulated phosphoprotein (VASP) is a regulator of actin dynamics in platelets and a common substrate of both cAMP- and cGMP-dependent protein kinases (PKA and PKG). Elevations of the cAMP and cGMP concentration have been shown to inhibit platelet aggregation. Intracellular levels of cAMP and cGMP are regulated by the synthesizing system of Adenylate Cyclases, and hydrolysis by cyclic nucleotide phosphodiesterases (PDEs). The present study examined the effect of the anti-platelet drug, cilostazol, which inhibits PDE3 activity, on VASP phosphorylation in platelets. VASP phosphorylation was examined by immunoblotting with an anti-VASP antibody, M4, and an anti-phospho-VASP antibody, 16C2. Cilostazol phosphorylated VASP at both Ser157 and Ser239 in a concentration-dependent manner, but EHNA (PDE2 inhibitor), dipyridamole and zaprinast (PDE5 inhibitors) did not. Forskolin (Adenylate Cyclase Activator) and sodium nitroprusside (SNP, NO donor) resulted in the VASP phosphorylation, with increase in the cAMP and cGMP level, respectively. Cilostazol increased cAMP, but not cGMP levels, in platelets. EHNA, zaprinast and dipyridamole, had no effect on cAMP and cGMP levels. The PKA/PKG inhibitor, H-89, inhibited VASP phosphorylation by cilostazol. These results demonstrated that cilostazol phosphorylates VASP through the PDE3 inhibition, increase of cAMP level, and PKA activation in platelets.

Nick Sperelakis - One of the best experts on this subject based on the ideXlab platform.

  • relaxation of subarachnoid hemorrhageinduced spasm of rabbit basilar artery by the k channel Activator cromakalim
    Stroke, 1996
    Co-Authors: Mario Zuccarello, Christian L Bonasso, Adam I Lewis, Nick Sperelakis, Robert M Rapoport
    Abstract:

    Background and Purpose Cerebral vasospasm resulting from subarachnoid hemorrhage (SAH) is refractory to most vasodilators. However, despite evidence that a mechanism underlying the vasospasm may be smooth muscle cell membrane depolarization resulting from decreased K+ conductance, the ability of K+ channel Activators to relax the spasm has not been thoroughly investigated. The purpose of this study, therefore, was to investigate whether K+ channel activation selectively relaxes SAH-induced vasospasm. Methods Three days after SAH in the rabbit, relaxation of the basilar artery in response to the K+ channel Activator cromakalim as well as to staurosporine (protein kinase C antagonist), forskolin (Adenylate Cyclase Activator), and sodium nitroprusside (guanylate Cyclase Activator) was measured in situ with the use of a cranial window. Relaxation in response to these agents was also investigated in control vessels contracted with serotonin. Membrane potential of the smooth muscle cells of the basilar artery f...

  • Isoproterenol- and insulin-induced hyperpolarization in rat skeletal muscle
    Journal of cellular physiology, 1993
    Co-Authors: Nick Sperelakis
    Abstract:

    Using conventional microelectrode techniques, we investigated the combined effects of isoproterenol (Iso) and insulin (Ins) on the resting membrane potential (RMP) of isolated rat skeletal muscles. In soleus muscle, Iso (1 μM) and Ins (4 units/L) separately induced a hyperpolarization of 9.2 mV and 4.8 mV, respectively. Combined administration of Iso and Ins induced a hyperpolarization of 12.4 mV, larger than either one separately. A similar observation was made in Na+-loaded rewarming experiments. 8-Br-cAMP (1 mM and 3 mM) and forskolin (10 μM, an Adenylate Cyclase Activator) induced a hyperpolarization of 5.3 mV, 8 mV, and 6.0 mV, respectively. This hyperpolarizing action was blocked by ouabain indicating that the Na-K pump was involved in the hyperpolarization. 8-BrcGMP (3 mM) had no effect on RMP; however, it blocked or reversed the hyperpolarization caused by 8-Br-cAMP (1 mM). In addition, 8-Br-cGMP partially inhibited the hyperpolarizing effect of Iso (1 μM) by 40% and completely prevented the effect of Ins. The phorbol ester, PMA, (1 μM, a PKC Activator) induced a ouabain-inhibitable hyperpolarization. These results suggest that cAMP and PKC are involved in the Iso- and Ins-induced hyperpolarization and that Iso and Ins influence the RMP presumably through regulation of the electrogenic Na-K pump via different mechanisms. © 1993 Wiley-Liss, Inc.

David E Pleasure - One of the best experts on this subject based on the ideXlab platform.

  • Schwann cell-autonomous role of neuropilin-2.
    Journal of neuroscience research, 2005
    Co-Authors: Jahan Ara, Peter Bannerman, F. Shaheen, David E Pleasure
    Abstract:

    Neuropilins and group A plexins are components of receptor complexes for class 3 semaphorins, gradients of which help to guide migration of neural progenitor cells and axonal growth cones during development. We demonstrated previously that neuropilins and class 3 semaphorins are induced in sciatic nerve by crush or transection. We now report that in cultured rat Schwann cells, expression of mRNA encoding neuropilin-2 (NRP2) and plexin-A3 (PlexA3), proteins involved in semaphorin-3F (Sema3F) signal transduction, is diminished markedly by forskolin, an Adenylate Cyclase Activator that, like axonal contact, induces Schwann cell synthesis of myelin lipids and proteins. Interestingly, Schwann cell expression of mRNA encoding NRP1, which participates in Sema3A signaling, is not downregulated by forskolin. Antibodies that recognize ectodomains of NRP2 but not control antibodies prevented cultured Schwann cells from aligning in parallel and forming columns. These results are consistent with the view that in nerves undergoing Wallerian degeneration, Schwann cell NRP2 facilitates assembly of Schwann cells into the tubular aggregates (bands of Bungner) that guide regenerating axons.

  • immunocytochemical expression of human muscle cell p75 neurotrophin receptor is down regulated by cyclic adenosine 3 5 monophosphate
    Neuroscience Letters, 1997
    Co-Authors: Pierluigi Baron, David E Pleasure, Elio Scarpini, Silvia Pizzul, Fabrizio Zotti, Giancarlo Conti, G Scarlato
    Abstract:

    Abstract To investigate whether the immunocytochemical expression of low affinity neurotrophin receptor (p75) in human muscle is modulated by increased levels of intracellular cyclic adenosine 3′,5′-monophoshate (cAMP), human cultured myogenic cells were treated with cAMP analogues dibutyryl cAMP (dbcAMP 0.5–1 mM) and 8-bromo cAMP (1 mM) or the Adenylate Cyclase Activator forskolin (10–100 μ M). Cultures were processed for indirect immunofluorescence microscopy using an anti-human p75 mAb. The treatment of cultured muscle cells with cAMP analogues or forskolin for two days induced a decrease of immunoreactivity for p75 and a reduction of both myotube formation and morphological cell differentiation. Removal of cAMP derivatives from the medium resulted in a return of immunoreactive cells to the levels of untreated controls. These data indicate that Adenylate Cyclase is involved in the regulation of human muscle p75.

Hideki Ito - One of the best experts on this subject based on the ideXlab platform.

  • Phosphorylation of the vasodilator-stimulated phosphoprotein (VASP) by the anti-platelet drug, cilostazol, in platelets.
    Platelets, 2003
    Co-Authors: Toshiki Sudo, Hideki Ito, Yukio Kimura
    Abstract:

    Vasodilator-stimulated phosphoprotein (VASP) is a regulator of actin dynamics in platelets and a common substrate of both cAMP- and cGMP-dependent protein kinases (PKA and PKG). Elevations of the cAMP and cGMP concentration have been shown to inhibit platelet aggregation. Intracellular levels of cAMP and cGMP are regulated by the synthesizing system of Adenylate Cyclases, and hydrolysis by cyclic nucleotide phosphodiesterases (PDEs). The present study examined the effect of the anti-platelet drug, cilostazol, which inhibits PDE3 activity, on VASP phosphorylation in platelets. VASP phosphorylation was examined by immunoblotting with an anti-VASP antibody, M4, and an anti-phospho-VASP antibody, 16C2. Cilostazol phosphorylated VASP at both Ser157 and Ser239 in a concentration-dependent manner, but EHNA (PDE2 inhibitor), dipyridamole and zaprinast (PDE5 inhibitors) did not. Forskolin (Adenylate Cyclase Activator) and sodium nitroprusside (SNP, NO donor) resulted in the VASP phosphorylation, with increase in the cAMP and cGMP level, respectively. Cilostazol increased cAMP, but not cGMP levels, in platelets. EHNA, zaprinast and dipyridamole, had no effect on cAMP and cGMP levels. The PKA/PKG inhibitor, H-89, inhibited VASP phosphorylation by cilostazol. These results demonstrated that cilostazol phosphorylates VASP through the PDE3 inhibition, increase of cAMP level, and PKA activation in platelets.