title: Pressure-flow relationship in swine ureter: effect of nitric oxide synthase inhibition by L-NAME.
abstract: BACKGROUND
  The purpose of this report is to elucidate the possible role of nitric oxide (NO) in modulating smooth muscle tone of swine ureteral wall and its hydraulic resistance to urinary flow.
  
  
  METHODS
  We performed direct monitoring of perfusion pressure for different flows in isolated fresh swine ureter. Fluid used for perfusions was saline or L-NAME 200 mumol saline added, and relative pressure-flow relationships were obtained.
  
  
  RESULTS
  The general shape of pressure-flow relationships indicates a decrease of ureteral hydraulic resistance with increasing flow. NO synthase inhibition by L-NAME caused a statistically significant increase of perfusion pressures for every tested flow, hence of ureteral hydraulic resistance.
  
  
  CONCLUSIONS
  Our data show an effective role of NO in modulating ureteral flow resistance, and suggest possible pharmacological implications. A simple mathematical approach to define hydraulic ureteral flow resistance for low and high urinary flows is also suggested.
authors.affiliation: Department of Human Anatomy and Physiology, Section of Physiology, University of Padova, Padova, Italy. alessandro.rubini@unipd.it
authors.forename: Alessandro
authors.initials: A
authors.lastname: Rubini
authors.forename: Marco
authors.initials: M
authors.lastname: Redaelli
authors.forename: Michela
authors.initials: M
authors.lastname: Bondì
mesh_terms: D000818:Animals; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005260:Female; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors* / Q000502:physiology; D011312:Pressure; D013552:Swine; D014513:Ureter / Q000502:physiology*; D014563:Urodynamics
chemical_list: D004791:Enzyme Inhibitors; D019001:Nitric Oxide Synthase; D019331:NG-Nitroarginine Methyl Ester