title: Decreased expression of hyperpolarisation-activated cyclic nucleotide-gated channel 3 in Hirschsprung's disease.
abstract: OBJECTIVE
  To determine if hyperpolarisation-activated nucleotide-gated (HCN) channels exist in human colon, and to investigate the expression of HCN channels in Hirschsprung's disease.
  
  
  METHODS
  We investigated HCN1, HCN2, HCN3 and HCN4 protein expression in pull-through specimens from patients with Hirschsprung's disease (HSCR, n = 10) using the proximal-most ganglionic segment and distal-most aganglionic segment, as well as in healthy control specimens obtained at the time of sigmoid colostomy closure in children who had undergone anorectoplasty for imperforate anus (n = 10). Fluorescent immunohistochemistry was performed to assess protein distribution, which was then visualized using confocal microscopy.
  
  
  RESULTS
  No HCN1 channel expression was observed in any of the tissues studied. Both HCN2 and HCN4 proteins were found to be equally expressed in the aganglionic and ganglionic bowel in HSCR and controls. HCN3 channel expression was found to be markedly decreased in the aganglionic colon vs ganglionic colon and controls. HCN2-4 channels were seen to be expressed within neurons of the myenteric and submucosal plexus of the ganglionic bowel and normal controls, and also co-localised to interstitial cells of Cajal in all tissues studied.
  
  
  CONCLUSIONS
  We demonstrate HCN channel expression in human colon for the first time. Reduced HCN3 expression in aganglionic bowel suggests its potential role in HSCR pathophysiology.
authors.affiliation: Anne Marie O'Donnell, David Coyle, Prem Puri, National Children's Research Centre, Our Lady's Children's Hospital, Crumlin, Dublin 12, Ireland.
authors.forename: Anne Marie
authors.initials: AM
authors.lastname: O'Donnell
authors.affiliation: Anne Marie O'Donnell, David Coyle, Prem Puri, National Children's Research Centre, Our Lady's Children's Hospital, Crumlin, Dublin 12, Ireland.
authors.forename: David
authors.initials: D
authors.lastname: Coyle
authors.affiliation: Anne Marie O'Donnell, David Coyle, Prem Puri, National Children's Research Centre, Our Lady's Children's Hospital, Crumlin, Dublin 12, Ireland.
authors.forename: Prem
authors.initials: P
authors.lastname: Puri
mesh_terms: D015153:Blotting, Western; D003106:Colon / Q000737:chemistry* / Q000503:physiopathology; D015536:Down-Regulation; D005260:Female; D005455:Fluorescent Antibody Technique; D006627:Hirschsprung Disease / Q000175:diagnosis / Q000378:metabolism* / Q000503:physiopathology; D006801:Humans; D064428:Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels / Q000032:analysis*; D007223:Infant; D008297:Male; D018613:Microscopy, Confocal; D015221:Potassium Channels / Q000032:analysis*
chemical_list: C472018:HCN3 protein, human; D064428:Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels; D015221:Potassium Channels
keywords: Hirschsprung’s; Hyperpolarisation-activated nucleotide-gated; Ih current; Interstitial cells of Cajal; Pacemaker