title: Differential response to endothelial epithelial sodium channel inhibition ex vivo correlates with arterial stiffness in humans.
abstract: OBJECTIVE
  Recently, the nanomechanical properties (i.e. stiffness) of endothelial cells have been identified as crucial for appropriate endothelial function. One major determinant of endothelial stiffness is the endothelial sodium channel (EnNaC). EnNaC-dependent stiffening leads to reduced nitric oxide release, which is a hallmark for endothelial dysfunction. In the current study, we hypothesized that endothelial function is directly linked to the overall function of the arterial system.
  
  
  METHODS
  Sixty-four human ex-vivo arterial samples were collected from femoral bypass or vein-stripping procedures. Nanomechanical characteristics of ex-vivo endothelium from isolated arterial side branches were determined using atomic force microscopy. The endothelium's potential to respond to EnNaC inhibition by amiloride was defined as endothelial amiloride index. In addition, patients' arterial stiffness was determined by pulse wave velocity (PWV).
  
  
  RESULTS
  Fifty-three percentage of the ex-vivo samples responded 'classically' to amiloride with endothelial softening, whereas 47% of the patients' samples did not. Interestingly, a lack of endothelial softening in the presence of amiloride in vitro was observed with higher frequency among samples obtained from individuals with elevated PWV. Further, an increased PWV was associated with impaired renal function and endothelial dysfunction (higher levels of von Willebrand factor).
  
  
  CONCLUSIONS
  Here, we report differential responses of human ex-vivo vessels to amiloride. Although the mechanism of differential amiloride response is still unknown, the data indicate that drug action on endothelial function could differ strongly among patients, especially in those with a vascular end-organ damage determined by PWV.
authors.affiliation: aUniversity Hospital Muenster, Internal Medicine D, Nephrology, Hypertension and Rheumatology bUniversity of Muenster, Institute of Physiology II cUniversity Hospital Muenster, Institute of Sports Medicine, Molecular Genetics of Cardiovascular Disease dUniversity Hospital Muenster, Department of Vascular and Endovascular Surgery eUniversity of Muenster, Institute of Anatomy and Molecular Neurobiology, Muenster, Germany *Malte Lenders and Verena Hofschröer contributed equally to the writing of this article. †Kristina Kusche-Vihrog and Eva Brand contributed equally to the writing of this article.
authors.forename: Malte
authors.initials: M
authors.lastname: Lenders
authors.forename: Verena
authors.initials: V
authors.lastname: Hofschröer
authors.forename: Boris
authors.initials: B
authors.lastname: Schmitz
authors.forename: Bernd
authors.initials: B
authors.lastname: Kasprzak
authors.forename: Astrid
authors.initials: A
authors.lastname: Rohlmann
authors.forename: Markus
authors.initials: M
authors.lastname: Missler
authors.forename: Hermann
authors.initials: H
authors.lastname: Pavenstädt
authors.forename: Hans
authors.initials: H
authors.lastname: Oberleithner
authors.forename: Stefan-Martin
authors.initials: SM
authors.lastname: Brand
authors.forename: Kristina
authors.initials: K
authors.lastname: Kusche-Vihrog
authors.forename: Eva
authors.initials: E
authors.lastname: Brand
mesh_terms: D000328:Adult; D000368:Aged; D000584:Amiloride / Q000494:pharmacology; D001158:Arteries / Q000502:physiology; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000187:drug effects / Q000503:physiopathology*; D062686:Epithelial Sodium Channel Blockers / Q000494:pharmacology; D053503:Epithelial Sodium Channels / Q000187:drug effects / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D018625:Microscopy, Atomic Force; D008875:Middle Aged; D063177:Pulse Wave Analysis; D059289:Vascular Stiffness / Q000187:drug effects / Q000502:physiology*; D014841:von Willebrand Factor / Q000378:metabolism
chemical_list: D062686:Epithelial Sodium Channel Blockers; D053503:Epithelial Sodium Channels; D014841:von Willebrand Factor; D000584:Amiloride