title: Role of ATP-dependent K channels in the effects of erythropoietin in renal ischaemia injury.
abstract: OBJECTIVE
  Erythropoietin (EPO) has cytoprotective and anti-apoptotic effects in pathological conditions, including hypoxia and ischaemia-reperfusion injury. One of the targets to protect against injury is ATP-dependent potassium (KATP ) channels. These channels could be involved in EPO induced ischaemic preconditoning like a protective effect. We evaluated the cell cytoprotective effects of EPO in relation to KATP channel activation in the renal tubular cell culture model under hypoxic/normoxic conditions.
  
  
  METHODS
  Dose and time dependent effects of EPO, KATP channel blocker glibenclamide and KATP channel opener diazoxide on cellular proliferation were evaluated by colorimetric assay MTT [3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide] under normoxic and hypoxic conditions in human renal proximal tubular cell line (CRL-2830). Evaluation of the dose and time dependent effects of EPO, glibenclamide and diazoxide on apoptosis was done by caspase-3 activity levels. Hypoxia inducible factor-1 alpha (HIF-1 α) mRNA levels were measured by semi-quantative reverse transcription polymerase chain reaction (RT)-PCR. Kir 6.1 protein expresion was evalutaed by Western blot.
  
  
  RESULTS
  Glibenclamide treatment decreased the number of living cells in a time and dose dependent manner, whereas EPO and diazoxide treatments increased. Glibenclamide (100 μM) treatment significantly blocked the anti-apoptotic effects of EPO (10 IU/ml) under both normoxic and hypoxic conditions. EPO (10 IU/ml) and diazoxide (100 μM) treatments significantly increased (p <0.01) whereas glibenclamide decreased ( p<0.05) HIF-1 α mRNA expression. Glibenclamide significantly ( p<0.01) decreased EPO induced HIF-1 α mRNA expression when compared with the EPO alone group.
  
  
  CONCLUSIONS
  Our results showed that the cell proliferative, cytoprotective and anti-apoptotic effects of EPO were associated with KATP channels in the renal tubular cell culture model under hypoxic/normal conditions.
authors.affiliation: School of Medicine, Department of General Surgery, Kocaeli University, Kocaeli, Turkey.
authors.forename: Tonguc Utku
authors.initials: TU
authors.lastname: Yilmaz
authors.forename: Nuray
authors.initials: N
authors.lastname: Yazihan
authors.forename: Aydın
authors.initials: A
authors.lastname: Dalgic
authors.forename: Ezgi Ermis
authors.initials: EE
authors.lastname: Kaya
authors.forename: Bulent
authors.initials: B
authors.lastname: Salman
authors.forename: Mehtap
authors.initials: M
authors.lastname: Kocak
authors.forename: Ethem
authors.initials: E
authors.lastname: Akcil
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D003981:Diazoxide / Q000008:administration & dosage; D004921:Erythropoietin / Q000008:administration & dosage*; D005786:Gene Expression Regulation; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000096:biosynthesis; D054086:KATP Channels / Q000235:genetics*; D007668:Kidney / Q000187:drug effects* / Q000293:injuries; D007674:Kidney Diseases / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D007684:Kidney Tubules / Q000187:drug effects* / Q000473:pathology; D015427:Reperfusion Injury / Q000188:drug therapy / Q000235:genetics
chemical_list: C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D054086:KATP Channels; D004921:Erythropoietin; D003981:Diazoxide