title: Modulation of endothelin-1-induced cytosolic free calcium mobilization and mitogen-activated protein kinase activation by erythropoietin in vascular smooth muscle cells.
abstract: BACKGROUND
  It has been reported that human recombinant erythropoietin (rHuEPO) modulates the sensitivity of the cardiovascular system to vasoconstrictors. We investigated whether rHuEPO has modulative effects on the endothelin-1 (ET-1)-induced elevation of cytosolic free calcium concentration ([Ca2+]i) and mitogen-activated protein (MAP) kinase activation in vascular smooth muscle cells (VSMC).
  
  
  METHODS
  [Ca2+]i was measured by fura-2/AM, and MAP kinase activation was analyzed by Western blotting.
  
  
  RESULTS
  Exposure of VSMC to rHuEPO prior to stimulation with ET-1 enhanced both basal and ET-1-induced elevation of [Ca2+]i in a dose-dependent manner in the presence of extracellular Ca2+. The synergistic effect was also retained in the absence of extracellular Ca2+ after exposure to rHuEPO. However, the effect was diminished in the presence of extracellular Ca2+ combined with the intracellular Ca2+ release inhibitor TMB-8, PKC inhibitor, or PKC depletion. Exposure to rHuEPO also had a synergistic effect on the activation of MAP kinase induced by ET-1; however, this effect was diminished in the presence of the Ca2+ chelator BAPTA-AM.
  
  
  CONCLUSIONS
  The results suggest that rHuEPO has synergistic effects on ET-1-induced [Ca2+]i mobilization, particularly on intracellular Ca2+ release, and MAP kinase activation in VSMC.
authors.affiliation: Department of Nephrology, Jichi Medical School, Tochigi, Japan. eishun@jichi.ac.jp
authors.forename: E
authors.initials: E
authors.lastname: Kusano
authors.forename: T
authors.initials: T
authors.lastname: Akimoto
authors.forename: T
authors.initials: T
authors.lastname: Umino
authors.forename: S
authors.initials: S
authors.lastname: Yanagiba
authors.forename: M
authors.initials: M
authors.lastname: Inoue
authors.forename: C
authors.initials: C
authors.lastname: Ito
authors.forename: Y
authors.initials: Y
authors.lastname: Ando
authors.forename: Y
authors.initials: Y
authors.lastname: Asano
mesh_terms: D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D003600:Cytosol / Q000378:metabolism*; D019332:Endothelin-1 / Q000494:pharmacology*; D004789:Enzyme Activation; D004921:Erythropoietin / Q000494:pharmacology*; D005110:Extracellular Space / Q000378:metabolism; D006801:Humans; D015759:Ionomycin / Q000494:pharmacology; D007476:Ionophores / Q000494:pharmacology; D008297:Male; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism*; D009994:Osmolar Concentration; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000172:deficiency / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D011994:Recombinant Proteins / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D019332:Endothelin-1; D007476:Ionophores; D011994:Recombinant Proteins; D004921:Erythropoietin; D015759:Ionomycin; D011493:Protein Kinase C; D020928:Mitogen-Activated Protein Kinases; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium