title: Norepinephrine-induced calcium mobilization in C6 glioma cells.
abstract: OBJECTIVE
  To investigate the mechanism underlying the norepinephrine-induced elevation in intracellular calcium concentration ([Ca2+]i) in C6 glioma cells.
  
  
  METHODS
  Measurement of [Ca2+]i was carried out using the dual-wavelength fluorescence method with fura-2 as the indicator.
  
  
  RESULTS
  Norepinephrine was found to induce concentration-dependent increases in [Ca2+ ]i through alpha1-adrenoreceptors. The [Ca2+]i elevations were extracellular-calcium independent and not influenced by the treatment of pertussis toxin. Pretreatments with either U73122 or thapsigargin abolished the subsequent cellular calcium responses to norepinephrine. Preincubation with phorbol 12-myristate 13-acetate (PMA) significantly reduce d the [Ca2+]i elevations, while protein kinase C inhibitors Ro31-8220 or GF-109203X completely blocked the inhibitory action of PMA. However, drugs either activating or inhibiting the function of protein kinase A had no effect on the [Ca2+]i elevations.
  
  
  CONCLUSIONS
  Norepinephrine induces calcium mobilization from internal stores by activation of phospholipase C in C6 cells. The [Ca2+]i elevation is negatively regulated by the activation of protein kinase C.
authors.affiliation: Neuroscience Research Institute and Department of Neurobiology, College of Pharmacy, Second Military Medical University, Shanghai 200433, China.
authors.forename: Jian-Zhong
authors.initials: JZ
authors.lastname: Han
authors.forename: Wen
authors.initials: W
authors.lastname: Lin
authors.forename: Shu-Jie
authors.initials: SJ
authors.lastname: Lou
authors.forename: Yi-Zhang
authors.initials: YZ
authors.lastname: Chen
mesh_terms: D000818:Animals; D001693:Biological Transport, Active; D002118:Calcium / Q000378:metabolism*; D016257:Fura-2; D005910:Glioma / Q000378:metabolism* / Q000473:pathology; D009638:Norepinephrine / Q000494:pharmacology*; D011493:Protein Kinase C / Q000378:metabolism*; D051381:Rats; D011942:Receptors, Adrenergic, alpha / Q000378:metabolism; D014407:Tumor Cells, Cultured
chemical_list: D011942:Receptors, Adrenergic, alpha; D011493:Protein Kinase C; D002118:Calcium; D016257:Fura-2; D009638:Norepinephrine