title: Vasodilatory mechanisms of unoprostone isopropyl in isolated porcine retinal arterioles.
abstract: OBJECTIVE
  To clarify the vasodilatory mechanism of unoprostone isopropyl (UI), we examined its effects on the retinal microvascular diameter to determine the dependence on the endothelium and/or smooth muscle to reveal the signaling mechanisms involved in this vasomotor activity.
  
  
  METHODS
  Porcine retinal arterioles were isolated, cannulated, and pressurized without flow in vitro. Video microscopic techniques recorded the diametric responses to UI.
  
  
  RESULTS
  The retinal arterioles dilated in response to UI in a dose-dependent (100 pM-10 µM) manner. The nitric oxide (NO) synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME) inhibited UI-induced vasodilation. The large-conductance Ca2+-activated K channel (BKCa channel) blocker iberiotoxin also inhibited UI-induced vasodilation. The residual vasodilation after L-NAME was eliminated with co-administration of iberiotoxin.
  
  
  CONCLUSIONS
  UI elicits dilation of the retinal arterioles mediated by NO release and BKCa channel activation.
authors.affiliation: Department of Ophthalmology, Asahikawa Medical University, Asahikawa, Japan.
authors.forename: Ichiro
authors.initials: I
authors.lastname: Tanano
authors.affiliation: Department of Ophthalmology, Asahikawa Medical University, Asahikawa, Japan.
authors.forename: Taiji
authors.initials: T
authors.lastname: Nagaoka
authors.affiliation: Department of Ophthalmology, Asahikawa Medical University, Asahikawa, Japan.
authors.forename: Shinji
authors.initials: S
authors.lastname: Ono
authors.affiliation: Department of Ophthalmology, Asahikawa Medical University, Asahikawa, Japan.
authors.forename: Tsuneaki
authors.initials: T
authors.lastname: Omae
authors.affiliation: Department of Ophthalmology, Asahikawa Medical University, Asahikawa, Japan.
authors.forename: Shinichi
authors.initials: S
authors.lastname: Otani
authors.affiliation: Department of Ophthalmology, Asahikawa Medical University, Asahikawa, Japan.
authors.forename: Akitoshi
authors.initials: A
authors.lastname: Yoshida
mesh_terms: D000818:Animals; D001160:Arterioles / Q000187:drug effects / Q000502:physiology; D015237:Dinoprost / Q000031:analogs & derivatives* / Q000494:pharmacology; D045462:Endothelium-Dependent Relaxing Factors / Q000378:metabolism; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D018715:Microscopy, Video; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism; D009599:Nitroprusside / Q000494:pharmacology; D015221:Potassium Channels / Q000378:metabolism; D012171:Retinal Vessels / Q000187:drug effects* / Q000502:physiology; D034421:Sus scrofa; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology; D014665:Vasodilator Agents / Q000494:pharmacology*
chemical_list: D045462:Endothelium-Dependent Relaxing Factors; D015221:Potassium Channels; D014665:Vasodilator Agents; D009599:Nitroprusside; D009569:Nitric Oxide; C072630:isopropyl unoprostone; D015237:Dinoprost; D019331:NG-Nitroarginine Methyl Ester