title: Natriuretic effect of adenosine A1-receptor blockade in rats.
abstract: BACKGROUND
  Many effects of adenosine on renal function have been identified. The development of adenosine receptor blockers has made it possible to identify which of these effects are exerted by endogenous adenosine. At least four adenosine receptor subtypes, denoted A1, A2a, A2b, and A3 are currently known. In the present study the selective A1 receptor blocker 1,3-dipropyl-8[2-(5,6-epoxy) norbanyl] xanthine (CVT-117) was used to assess the effect of A1 activation by endogenous adenosine on renal function in rats.
  
  
  METHODS
  Clearance studies were performed before and after administration of 0.1 mg/kg and 0.8 mg/kg of CVT-117 in separate groups of rats and before and after administration of vehicle in time-control rats. Measurements of heart rate before and after administration of exogenous adenosine confirmed effective A1 receptor blockade.
  
  
  RESULTS
  At both the lower and higher doses, A1 receptor blockade with CVT-117 increased fractional sodium excretion and urine flow rate without altering GFR. The increase in sodium excretion following A1 blockade was not accompanied by increases in the excretion of phosphate or potassium.
  
  
  CONCLUSIONS
  These results show that endogenous adenosine promotes sodium retention by activation of A1 receptors.
authors.affiliation: Department of Medicine, University of Vienna, Austria.
authors.forename: R
authors.initials: R
authors.lastname: Oberbauer
authors.forename: G F
authors.initials: GF
authors.lastname: Schreiner
authors.forename: T W
authors.initials: TW
authors.lastname: Meyer
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D005919:Glomerular Filtration Rate / Q000187:drug effects; D008297:Male; D009318:Natriuresis / Q000187:drug effects*; D058915:Purinergic P1 Receptor Antagonists; D051381:Rats; D017207:Rats, Sprague-Dawley; D014970:Xanthines / Q000494:pharmacology*
chemical_list: C097280:1,3-dipropyl-8-(2-(5,6-epoxy)norbornyl)xanthine; D058915:Purinergic P1 Receptor Antagonists; D014970:Xanthines