title: Comparative study of cyclosporine and tacrolimus vs newer immunosuppressants mycophenolate mofetil and rapamycin on coronary endothelial function.
abstract: BACKGROUND
  Endothelial dysfunction contributes to the development of intimal hyperplasia in transplanted hearts by decreasing the protective effects of endothelial-derived nitric oxide. Immunosuppressive drugs may increase the dysfunction caused by rejection and further accelerate the development of graft coronary vasculopathy. This study compares the effect of cyclosporine and tacrolimus vs two newer immunosuppressive drugs, mycophenolate mofetil and rapamycin, on coronary endothelial function.
  
  
  METHODS
  An in vitro model of drug incubation in Krebs-bicarbonate solution (4(o)C, 48 hours) using porcine epicardial coronary arteries was developed. Coronary endothelial function studies were performed in organ chamber experiments after incubation with cyclosporine (10(-4), 10(-7) mol/liter), tacrolimus (10(-4), 10(-7) mol/liter), mycophenolate mofetil (10(-4), 10(-7) mol/liter), rapamycin (10(-7), 10(-11) mol/liter), and their vehicles to assess effects on G-protein-mediated vasorelaxations leading to the release of nitric oxide.
  
  
  RESULTS
  Exposure to cyclosporine and mycophenolate mofetil was associated with a dose-dependent decrease in endothelium-dependent relaxations to serotonin (an agonist that binds to 5-HT1D receptors coupled to Gi-protein) but no impairment of relaxations to bradykinin (an agonist that binds to B2 receptors coupled to Gq-proteins). Exposure to tacrolimus and rapamycin caused severe impairment of relaxations to serotonin and a lesser one to bradykinin. We observed alterations of relaxations to the calcium ionophore A23187 after exposure to mycophenolate mofetil and rapamycin. Exposure to rapamycin and mycophenolate mofetil vehicles impaired relaxation to all agonists.
  
  
  CONCLUSIONS
  These results suggest that cyclosporine and mycophenolate mofetil induce a dysfunction of the vasorelaxing properties of the endothelium that may lead to a decrease in the protective effects of nitric oxide on the vascular wall but that these drugs still have a more favorable vascular profile than do tacrolimus and rapamycin. Decreased endothelial function after mycophenolate mofetil and rapamycin exposure could be caused by their vehicles.
authors.affiliation: Research Center and Department of Surgery, Montreal Heart Institute, Quebec, Canada.
authors.forename: Hugues
authors.initials: H
authors.lastname: Jeanmart
authors.forename: Olivier
authors.initials: O
authors.lastname: Malo
authors.forename: Michel
authors.initials: M
authors.lastname: Carrier
authors.forename: Caroline
authors.initials: C
authors.lastname: Nickner
authors.forename: Nathalie
authors.initials: N
authors.lastname: Desjardins
authors.forename: Louis P
authors.initials: LP
authors.lastname: Perrault
mesh_terms: D000818:Animals; D003326:Coronary Circulation / Q000187:drug effects; D016572:Cyclosporine / Q000009:adverse effects*; D004305:Dose-Response Relationship, Drug; D004359:Drug Therapy, Combination; D004730:Endothelium, Vascular / Q000187:drug effects*; D007166:Immunosuppressive Agents / Q000009:adverse effects*; D066298:In Vitro Techniques; D023421:Models, Animal; D009173:Mycophenolic Acid / Q000009:adverse effects* / Q000031:analogs & derivatives; D020123:Sirolimus / Q000009:adverse effects*; D013552:Swine; D016559:Tacrolimus / Q000009:adverse effects*; D014661:Vasoconstriction / Q000187:drug effects; D014664:Vasodilation / Q000187:drug effects*
chemical_list: D007166:Immunosuppressive Agents; D016572:Cyclosporine; D009173:Mycophenolic Acid; D020123:Sirolimus; D016559:Tacrolimus