title: Inhibition of Rho-kinase stimulates nitric oxide-independent vasorelaxation.
abstract: Vasoconstrictor factors, like urotensin, angiotensin and catecholamines, activate Rho-dependent serine-threonine kinase (Rho-kinase) and inhibition of this pathway represents a novel therapy for cardiovascular diseases with hypertensive syndrome. The disbalance of relaxing endothelial nitric oxide (NO)-producing and vasoconstrictive pathways can be especially important in diseases where hypertension is accompanied by endothelial dysfunction that compromises NO generation. However, a recent study reported that the efficacy of the Rho-kinase inhibitor (R)-(+)-trans-N-(4-Pyridyl)-4-(1-aminoethyl)cyclohexanecarboxamide (Y27632) is dramatically attenuated upon removal of endothelium or inhibition of endothelial NO synthase (eNOS). This raises the question whether Rho-kinase inhibition could be an effective treatment in case of hypertension associated with endothelial dysfunction. The purpose of the present study was to determine whether the vasorelaxing effect of Rho-kinase inhibition is mediated through eNOS-dependent mechanisms. We show here that in the models of genetically reduced endothelial NO production (eNOS-/- mice and spontaneous hypertensive rats (SHR)) or in models of pharmacologically reduced endogenous NO production (N(omega)-nitro-L-arginine methyl ester (LNAME) treatment), Rho-kinase inhibition induced a strong vasodilation and reduction of blood pressure indicating independence of Rho-kinase pathway from eNOS. An additional important finding of our study is that Rho-kinase inhibitors induce a strong vasorelaxation and blood pressure reduction upon intravenous injection not only in hypertensive but in normotensive animals, as well. Inhibition of Rho-kinase represents a promising possibility to treat hypertension that is accompanied by endothelial dysfunction.
authors.affiliation: Aventis Pharma GmbH, Department Cardiovascular Diseases, Industriepark Höchst, 65926 Frankfurt am Main, Germany. matthias.loehn@aventis.com
authors.forename: Matthias
authors.initials: M
authors.lastname: Löhn
authors.forename: Kerstin
authors.initials: K
authors.lastname: Steioff
authors.forename: Markus
authors.initials: M
authors.lastname: Bleich
authors.forename: Andreas E
authors.initials: AE
authors.lastname: Busch
authors.forename: Yuri
authors.initials: Y
authors.lastname: Ivashchenko
mesh_terms: D000818:Animals; D004305:Dose-Response Relationship, Drug; D066298:In Vitro Techniques; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000037:antagonists & inhibitors / Q000378:metabolism*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors* / Q000502:physiology*; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology*; D054460:rho-Associated Kinases
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; D047428:Protein Kinase Inhibitors; D009569:Nitric Oxide; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; D019331:NG-Nitroarginine Methyl Ester