title: Calcium channel blockade reduces mechanical strain-induced extracellular matrix gene response in lamina cribrosa cells.
abstract: OBJECTIVE
  This study examines the effect of the L-type calcium channel blocker verapamil on mechanical strain-induced extracellular matrix genes in optic nerve head lamina cribrosa (LC) cells.
  
  
  METHODS
  Changes in LC cell intracellular calcium [Ca(2+)]i following hypotonic cell membrane stretch were measured with the fluorescent probe fura-2/AM. Fluorescence intensity was measured, after labelling, by calcium (Ca2+) imaging confocal microscopy. Confluent human LC cell cultures were serum starved for 24 h prior to exposure to cyclical mechanical strain (1 Hz, 15%) for 24 h in the presence or absence of verapamil (10 mm). Transforming growth factor-β 1 (TGF-β1), collagen 6A3 (COL6A3) and chondroitin sulfate proteoglycan 2 (CSPG2) mRNA expression levels were assessed by quantitative RT-PCR.
  
  
  RESULTS
  Hypotonic cell membrane stretch of LC cells from normal donors significantly increased [Ca2+]i (p<0.05). Exposure to cyclical mechanical strain (15% strain) produced a statistically significant increase in the three matrix genes that were examined (TGF-β1, COL6A3 and CSPG2). This response in both cyclical and mechanical stretch was significantly reduced by pretreating LC cells with the L-type calcium channel blocker verapamil (p<0.05).
  
  
  CONCLUSIONS
  This study provides evidence of a novel mechanotransduction pathway linking mechanical strain, cation channel function and the induction of LC cell matrix gene transcription. This highlights the potential involvement of calcium influx in the activation of matrix remodelling responses in the optic nerve head and supports the rationale that calcium channel blockers may attenuate disease progression in glaucoma.
authors: Institute of Ophthalmology, Mater Misericordiae University Hospital, Dublin, Ireland Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Dublin, Ireland University College Dublin School of Medicine and Health Sciences, University College Dublin, Dublin, Ireland.
authors: B
authors: B
authors: Quill
authors: Institute of Ophthalmology, Mater Misericordiae University Hospital, Dublin, Ireland Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Dublin, Ireland.
authors: M
authors: M
authors: Irnaten
authors: Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Dublin, Ireland University College Dublin School of Medicine and Health Sciences, University College Dublin, Dublin, Ireland.
authors: N G
authors: NG
authors: Docherty
authors: Institute of Ophthalmology, Mater Misericordiae University Hospital, Dublin, Ireland Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Dublin, Ireland University College Dublin School of Medicine and Health Sciences, University College Dublin, Dublin, Ireland.
authors: E M
authors: EM
authors: McElnea
authors: Institute of Ophthalmology, Mater Misericordiae University Hospital, Dublin, Ireland Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Dublin, Ireland University College Dublin School of Medicine and Health Sciences, University College Dublin, Dublin, Ireland.
authors: D M
authors: DM
authors: Wallace
authors: University College Dublin School of Medicine and Health Sciences, University College Dublin, Dublin, Ireland.
authors: A F
authors: AF
authors: Clark
authors: Institute of Ophthalmology, Mater Misericordiae University Hospital, Dublin, Ireland Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Dublin, Ireland University College Dublin School of Medicine and Health Sciences, University College Dublin, Dublin, Ireland.
authors: C J
authors: CJ
authors: O'Brien
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002118:Calcium / Q000378:metabolism; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D020746:Calcium Channels, L-Type / Q000502:physiology*; D002478:Cells, Cultured; D024142:Collagen Type VI / Q000235:genetics; D005109:Extracellular Matrix / Q000235:genetics*; D016257:Fura-2 / Q000031:analogs & derivatives / Q000378:metabolism; D005786:Gene Expression Regulation / Q000502:physiology*; D006801:Humans; D040542:Mechanotransduction, Cellular / Q000187:drug effects* / Q000502:physiology; D018613:Microscopy, Confocal; D009898:Optic Disk / Q000166:cytology; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D013314:Stress, Mechanical; D053773:Transforming Growth Factor beta1 / Q000235:genetics; D014700:Verapamil / Q000494:pharmacology*; D053675:Versicans / Q000235:genetics
chemical_list: C000601102:COL6A3 protein, human; D002121:Calcium Channel Blockers; D020746:Calcium Channels, L-Type; D024142:Collagen Type VI; D012333:RNA, Messenger; D053773:Transforming Growth Factor beta1; C508322:VCAN protein, human; C049925:fura-2-am; D053675:Versicans; D014700:Verapamil; D002118:Calcium; D016257:Fura-2
keywords: Glaucoma