title: Marinobufagenin-induced vascular fibrosis is a likely target for mineralocorticoid antagonists.
abstract: OBJECTIVE
  Endogenous cardiotonic steroids, including marinobufagenin (MBG), stimulate vascular synthesis of collagen. Because mineralocorticoid antagonists competitively antagonize effect of cardiotonic steroids on the Na/K-ATPase, we hypothesized that spironolactone would reverse the profibrotic effects of MBG.
  
  
  METHODS
  Experiment 1: Explants of thoracic aortae and aortic vascular smooth muscle cells from Wistar rats were cultured for 24 h in the presence of vehicle or MBG (100 nmol/l) with or without canrenone (10 μmol/l), an active metabolite of spironolactone. Experiment 2: In 16 patients (56 ± 2 years) with resistant hypertension on a combined (lisinopril/amlodipine/hydrochlorothiazide) therapy, we determined arterial pressure, pulse wave velocity, plasma MBG, and erythrocyte Na/K-ATPase before and 6 months after addition of placebo (n = 8) or spironolactone (50 mg/day; n = 8) to the therapy.
  
  
  RESULTS
  In rat aortic explants and in vascular smooth muscle cells, pretreatment with MBG resulted in a two-fold rise in collagen-1, and a marked reduction in the sensitivity of the aortic rings to the vasorelaxant effect of sodium nitroprusside following endothelin-1-induced constriction (EC50 = 480 ± 67 vs. 23 ± 3 nmol/l in vehicle-treated rings; P < 0.01). Canrenone blocked effects of MBG on collagen synthesis and restored sensitivity of vascular rings to sodium nitroprusside (EC50 = 17 ± 1 nmol/l). Resistant hypertension patients exhibited elevated plasma MBG (0.42 ± 0.07 vs. 0.24 ± 0.03 nmol/l; P = 0.01) and reduced Na/K-ATPase activity (1.9 ± 0.15 vs. 2.8 ± 0.2 μmol Pi/ml per h, P < 0.01) vs. seven healthy individuals. Six-month administration of spironolactone, unlike placebo treatment, was associated with a decrease in pulse wave velocity and arterial pressure, and with restoration of Na/K-ATPase activity in the presence of unchanged MBG levels.
  
  
  CONCLUSIONS
  MBG-induced vascular fibrosis is a likely target for spironolactone.
authors.affiliation: aNational Institute on Aging, NIH, Baltimore, Maryland, USA bInstitute of Heart and Vessels, Almazov Federal Heart, Blood and Endocrinology Centre, St. Petersburg, Russia cDepartment of Biotechnology, Technion Institute, Haifa, Israel dSechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg, Russia.
authors.forename: Olga V
authors.initials: OV
authors.lastname: Fedorova
authors.forename: Igor V
authors.initials: IV
authors.lastname: Emelianov
authors.forename: Konstantin A
authors.initials: KA
authors.lastname: Bagrov
authors.forename: Yulia N
authors.initials: YN
authors.lastname: Grigorova
authors.forename: Wen
authors.initials: W
authors.lastname: Wei
authors.forename: Ondrej
authors.initials: O
authors.lastname: Juhasz
authors.forename: Elena V
authors.initials: EV
authors.lastname: Frolova
authors.forename: Courtney A
authors.initials: CA
authors.lastname: Marshall
authors.forename: Edward G
authors.initials: EG
authors.lastname: Lakatta
authors.forename: Alexandra O
authors.initials: AO
authors.lastname: Konradi
authors.forename: Alexei Y
authors.initials: AY
authors.lastname: Bagrov
mesh_terms: D000818:Animals; D001011:Aorta / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D062186:Arterial Pressure / Q000187:drug effects; D002018:Bufanolides / Q000009:adverse effects* / Q000037:antagonists & inhibitors* / Q000097:blood; D002192:Canrenone / Q000494:pharmacology*; D002478:Cells, Cultured; D024042:Collagen Type I / Q000378:metabolism; D019332:Endothelin-1 / Q000494:pharmacology; D004912:Erythrocytes / Q000201:enzymology; D005260:Female; D005355:Fibrosis / Q000139:chemically induced / Q000517:prevention & control; D006801:Humans; D006973:Hypertension / Q000097:blood / Q000188:drug therapy*; D008297:Male; D008875:Middle Aged; D000451:Mineralocorticoid Receptor Antagonists / Q000494:pharmacology*; D009131:Muscle, Smooth, Vascular / Q000166:cytology; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000378:metabolism; D009599:Nitroprusside / Q000494:pharmacology; D063177:Pulse Wave Analysis; D051381:Rats; D017208:Rats, Wistar; D000254:Sodium-Potassium-Exchanging ATPase / Q000097:blood; D013148:Spironolactone / Q000627:therapeutic use*; D014665:Vasodilator Agents / Q000494:pharmacology
chemical_list: D002018:Bufanolides; D024042:Collagen Type I; D019332:Endothelin-1; D000451:Mineralocorticoid Receptor Antagonists; D014665:Vasodilator Agents; D009599:Nitroprusside; D013148:Spironolactone; C093896:marinobufagenin; D002192:Canrenone; D000254:Sodium-Potassium-Exchanging ATPase