title: The (pro)renin receptor blocker handle region peptide upregulates endothelium-derived contractile factors in aliskiren-treated diabetic transgenic (mREN2)27 rats.
abstract: BACKGROUND
  Elevated prorenin levels associate with microvascular complications in patients with diabetes mellitus, possibly because prorenin affects vascular function in diabetes mellitus, for example by generating angiotensins following its binding to the (pro)renin receptor [(P)RR]. Here we evaluated whether the renin inhibitor aliskiren, with or without the putative (P)RR antagonist handle region peptide (HRP) improved the disturbed vascular function in diabetic TGR(mREN2)27 rats, a high-prorenin, high-(P)RR hypertensive model.
  
  
  METHODS
  Telemetry transmitters were implanted to monitor blood pressure. After 3 weeks of treatment, rats were sacrificed, and iliac and mesenteric arteries were removed to evaluate vascular reactivity.
  
  
  RESULTS
  Diabetes mellitus enhanced the contractile response to nitric oxide synthase (NOS) blockade, potentiated the response to phenylephrine, diminished the effectiveness of endothelin type A (ETA) receptor blockade and allowed acetylcholine to display constrictor, cyclo-oxygenase-2 mediated, endothelium-dependent responses in the presence of NOS inhibition and blockers of endothelium-derived hyperpolarizing factors. Aliskiren normalized blood pressure, suppressed renin activity, and reversed the above vascular effects, with the exception of the altered effectiveness of ETA receptor blockade. Remarkably, when adding HRP on top of aliskiren, its beneficial vascular effects either disappeared or were greatly diminished, although HRP did not alter the effect of aliskiren on blood pressure and renin activity.
  
  
  CONCLUSIONS
  Renin inhibition improves vascular dysfunction in diabetic hypertensive rats, and HRP counteracts this effect independently of blood pressure and angiotensin. (P)RR blockade therefore is unlikely to be a new tool to further suppress the renin-angiotensin system (RAS) on top of existing RAS blockers.
authors.affiliation: Division of Pharmacology and Vascular Medicine, Department of Internal Medicine, Erasmus MC, Rotterdam, The Netherlands.
authors.forename: Wendy W
authors.initials: WW
authors.lastname: Batenburg
authors.forename: Mieke
authors.initials: M
authors.lastname: van den Heuvel
authors.forename: Joep H M
authors.initials: JH
authors.lastname: van Esch
authors.forename: Richard
authors.initials: R
authors.lastname: van Veghel
authors.forename: Ingrid M
authors.initials: IM
authors.lastname: Garrelds
authors.forename: Frank
authors.initials: F
authors.lastname: Leijten
authors.forename: Alexander H J
authors.initials: AH
authors.lastname: Danser
mesh_terms: D000577:Amides / Q000494:pharmacology*; D000818:Animals; D001483:Base Sequence; D017931:DNA Primers; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism / Q000503:physiopathology*; D004730:Endothelium, Vascular / Q000378:metabolism / Q000503:physiopathology*; D005650:Fumarates / Q000494:pharmacology*; D009119:Muscle Contraction; D010455:Peptides / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D055647:Rats, Transgenic; D011956:Receptors, Cell Surface / Q000037:antagonists & inhibitors*; D015854:Up-Regulation / Q000502:physiology*; D000093342:Prorenin Receptor
chemical_list: D000577:Amides; D017931:DNA Primers; D005650:Fumarates; D010455:Peptides; D011956:Receptors, Cell Surface; C446481:aliskiren; D000093342:Prorenin Receptor