title: Decreased contraction to phenylephrine by ouabain in 2K-1C rat aorta is modulated by the endothelium.
abstract: The effects of ouabain were studied on the contraction stimulated with phenylephrine or KCl in intact endothelium and denuded aortic rings isolated from normotensive (2K) and renal hypertensive 2 kidney-1clip (2K-1C) rats. Ouabain did not change the basal tone of aortic rings. Ouabain (1 nmol/l) had no effect on the contraction to phenylephrine in all the artery groups studied. Ouabain (10 nmol/l) decreased the E(max) to phenylephrine in intact endothelium arteries from 2K-1C. By contrast, ouabain (10 nmol/l) had no effect on the contraction to KCl. Ouabain induced membrane depolarization measured by confocal image with Di-4-ANEPPS dye, that was greater in 2K than in 2K-1C rat aorta smooth muscle cells. In conclusion, ouabain (10 nmol/l) decreased the contractile responses to phenylephrine only in 2K-1C rat aortic rings with intact endothelium. Interestingly, 10 nmol/l ouabain depolarizes the smooth muscle cells but this depolarization level is not enough to alter the phenylephrine or KCl-induced contractions. Our results indicate that the endothelium modulates the vascular action of ouabain.
authors.affiliation: Laboratório de Farmacologia, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, Brazil.
authors.forename: Josiane C
authors.initials: JC
authors.lastname: Molin
authors.forename: Fabiana S
authors.initials: FS
authors.lastname: Sguilla
authors.forename: Lusiane M
authors.initials: LM
authors.lastname: Bendhack
mesh_terms: D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects* / Q000473:pathology / Q000503:physiopathology; D001794:Blood Pressure; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000503:physiopathology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006978:Hypertension, Renovascular / Q000503:physiopathology*; D066298:In Vitro Techniques; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000473:pathology / Q000503:physiopathology; D010042:Ouabain / Q000494:pharmacology*; D010656:Phenylephrine / Q000494:pharmacology*; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors; D014661:Vasoconstriction / Q000187:drug effects*; D014662:Vasoconstrictor Agents / Q000494:pharmacology
chemical_list: D004791:Enzyme Inhibitors; D014662:Vasoconstrictor Agents; D010656:Phenylephrine; D010042:Ouabain; D011189:Potassium Chloride; D000254:Sodium-Potassium-Exchanging ATPase