title: Vasoactivity of diadenosine polyphosphates in human small renal resistance arteries.
abstract: BACKGROUND
  We examined for the first time the vascular effects of purinergic agents that contribute to the regulation of peripheral vascular resistance in human small renal resistance arteries (hRRAs).
  
  
  RESULTS
  Diadenosine polyphosphates (ApnAs, n = 3-6) and ATP, mounted in a microvessel myograph, caused vasoconstriction in hRRAs (rank order of potency: Ap5A > Ap6A = Ap4A > Ap3A = ATP). ADP, AMP and adenosine had less contractile potency than ApnA, suggesting that the observed effects were not induced by ApnA degradation products. The ApnA agent, Ap5A, but not Ap4A, induced vasoconstrictions that were inhibited by pyridoxal phosphate-6-azophenyl-2',4'-disulfonic acid (PPADS; a P2X purinoceptor antagonist), but not by ADP3'5' (a P2Y purinoceptor antagonist). In pre-contracted hRRAs, all of the ApnA agents caused vasorelaxation, and the potencies did not differ from each other. The ApnA degradation products had less vasorelaxing potencies than ApnA, suggesting that the vasorelaxation was caused by the ApnA agents themselves. Ap4A-induced vasorelaxation was inhibited by ADP3'5' and PPADS. In contrast, Ap5A-induced vasorelaxation was not antagonized by ADP3'5', but was antagonized more strongly by PPADS than was Ap4A.
  
  
  CONCLUSIONS
  We found that the tone of resistance arteries in human kidneys can be considerably influenced by these purinergic agonists, and most potently by ApnAs. Ap5A-induced vasoconstriction appeared to be mediated by P2X purinoceptors, whereas constriction due to Ap4A was caused by a different purinoceptor. Vasorelaxation due to Ap4A, but not Ap5A, appeared to be mediated by P2Y purinoceptors.
authors: Department of Internal Medicine D, Nephrology and Experimental Nephrology, University Hospital Münster, Albert-Schweitzer-Strasse 33, D-48129 Münster, Germany. steinme@uni-muenster.de
authors: Martin
authors: M
authors: Steinmetz
authors: Gert
authors: G
authors: Gabriëls
authors: Truc Van
authors: TV
authors: Le
authors: Hans-Jürgen
authors: HJ
authors: Piechota
authors: Karl Heinz
authors: KH
authors: Rahn
authors: Eberhard
authors: E
authors: Schlatter
mesh_terms: D000227:Adenine Nucleotides / Q000494:pharmacology*; D000241:Adenosine / Q000494:pharmacology*; D015226:Dinucleoside Phosphates / Q000494:pharmacology*; D006439:Hemodynamics / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D066298:In Vitro Techniques; D007668:Kidney / Q000098:blood supply* / Q000187:drug effects / Q000503:physiopathology; D058914:Purinergic Antagonists; D012077:Renal Artery / Q000187:drug effects* / Q000502:physiology; D014655:Vascular Resistance / Q000187:drug effects; D014661:Vasoconstriction / Q000187:drug effects; D014664:Vasodilation / Q000187:drug effects
chemical_list: D000227:Adenine Nucleotides; D015226:Dinucleoside Phosphates; D058914:Purinergic Antagonists; D000241:Adenosine