title: Evidence of purinergic neurotransmission in isolated, intact horse sweat glands.
abstract: BACKGROUND
  Fluid secretion by sweat glands in response to heat and exercise is underpinned by increases in intracellular calcium. In horses, this is primarily via β2-adrenoceptors, but studies in equine sweat gland cell lines have indicated a possible role for purinergic agonists. Knowledge of equine sweating stimulus-secretion mechanisms in intact glands from healthy animals would allow future comparison to determine whether these mechanisms are affected in equine anhidrosis.
  
  
  OBJECTIVE
  To determine whether purinergic agonists can induce changes in intracellular calcium in intact, freshly isolated equine sweat glands.
  
  
  METHODS
  Eleven healthy thoroughbred horses from the Hong Kong Jockey Club were used in this study.
  
  
  METHODS
  Freshly isolated equine sweat glands were loaded with the calcium-sensitive fluorescent dye fura-2 AM, and changes in intracellular calcium were recorded before, during and after stimulation by purinergic agonists.
  
  
  RESULTS
  Purinergic agonists ATP and UTP generated significant increases in intracellular calcium.
  
  
  CONCLUSIONS
  The results show that it is possible to investigate stimulus-secretion coupling mechanisms by fluorescence imaging in equine sweat glands that have been isolated from fresh skin samples. Such isolated glands retain functional β2-adrenoceptors and P2Y purinergic receptors that couple to a calcium-signalling pathway. Using isolated, intact sweat glands therefore offers a very useful model for the further study of secretory processes in equine sweat glands, and using this experimental approach could facilitate a better understanding of how these mechanisms are affected in equine anhidrosis.
authors.affiliation: Department of Biological and Biomedical Sciences, Glasgow Caledonian University, Cowcaddens Road, Glasgow, G4 0BA, UK. d.bovell@gcal.ac.uk
authors.forename: Douglas L
authors.initials: DL
authors.lastname: Bovell
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Riggs
authors.forename: Gordon
authors.initials: G
authors.lastname: Sidlow
authors.forename: Suzanne
authors.initials: S
authors.lastname: Troester
authors.forename: William
authors.initials: W
authors.lastname: MacLaren
authors.forename: Wallace
authors.initials: W
authors.lastname: Yip
authors.forename: Wing H
authors.initials: WH
authors.lastname: Ko
mesh_terms: D000818:Animals; D020013:Calcium Signaling; D016257:Fura-2 / Q000031:analogs & derivatives; D006736:Horses / Q000502:physiology*; D007545:Isoproterenol; D018343:Receptors, Adrenergic, beta-2 / Q000502:physiology; D011983:Receptors, Purinergic / Q000502:physiology*; D013194:Staining and Labeling; D013545:Sweat Glands / Q000502:physiology*; D009435:Synaptic Transmission / Q000502:physiology*
chemical_list: D018343:Receptors, Adrenergic, beta-2; D011983:Receptors, Purinergic; C049925:fura-2-am; D007545:Isoproterenol; D016257:Fura-2