title: Involvement of protein kinase C and Na+/K+-ATPase in the contractile response induced by myricetin in rat isolated aorta.
abstract: The role of PKC and Na+/K+-ATPase in the vascular smooth muscle responses induced by the bioflavonoid myricetin was investigated. KCl induced a concentration-dependent relaxation in arteries exposed to K+-free solution that was mainly mediated by an activation of Na+/K+-ATPase. Myricetin (50 microM) partially inhibited this vasorelaxant effect induced by KCl in intact rings, being unaffected in the endothelium-denuded rings. This inhibitory effect induced by myricetin was suppressed by the PGH2-TXA2 receptor antagonist, SQ 29,548, and the PKC inhibitor, staurosporine. Myricetin also induced an endothelium-dependent contractile response which was increased in the presence of PMA and reduced by staurosporine. In conclusion, myricetin both modulates Na+/K+-ATPase-induced vasodilatation acting as a functional inhibitor of Na+/K+-ATPase activity and activates protein kinases, including PKC, to induce contraction. These effects appear to be related to the activation of PGH2-TXA2 receptors on vascular smooth muscle by the TXA2 released from endothelium.NA:noradrenalineNA+/K+-ATPase pump:sodium-potassium-activated ATPasePKC:protein kinase CPMA:phorbol 12-myristate 13-acetateTXA2:thromboxane A2The role of PKC and Na+/K+-ATPase in the vascular smooth muscle responses induced by the bioflavonoid myricetin was investigated. KCl induced a concentration-dependent relaxation in arteries exposed to K+-free solution that was mainly mediated by an activation of Na+/K+-ATPase. Myricetin (50 microM) partially inhibited this vasorelaxant effect induced by KCl in intact rings, being unaffected in the endothelium-denuded rings. This inhibitory effect induced by myricetin was suppressed by the PGH2-TXA2 receptor antagonist, SQ 29,548, and the PKC inhibitor, staurosporine. Myricetin also induced an endothelium-dependent contractile response which was increased in the presence of PMA and reduced by staurosporine. In conclusion, myricetin both modulates Na+/K+-ATPase-induced vasodilatation acting as a functional inhibitor of Na+/K+-ATPase activity and activates protein kinases, including PKC, to induce contraction. These effects appear to be related to the activation of PGH2-TXA2 receptors on vascular smooth muscle by the TXA2 released from endothelium.
authors.affiliation: Department of Pharmacology, School of Pharmacy, University of Granada, Granada, Spain.
authors.forename: Rosario
authors.initials: R
authors.lastname: Jiménez
authors.forename: Antonio
authors.initials: A
authors.lastname: Zarzuelo
authors.forename: Milagros
authors.initials: M
authors.lastname: Galisteo
authors.forename: Juan
authors.initials: J
authors.lastname: Duarte
mesh_terms: D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects* / Q000201:enzymology / Q000502:physiology; D019086:Bridged Bicyclo Compounds, Heterocyclic; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004730:Endothelium, Vascular / Q000187:drug effects; D005231:Fatty Acids, Unsaturated; D005260:Female; D005419:Flavonoids / Q000494:pharmacology*; D006834:Hydrazines / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D011189:Potassium Chloride / Q000494:pharmacology; D044262:Prostaglandin H2; D011463:Prostaglandins H / Q000378:metabolism; D011493:Protein Kinase C / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D011982:Receptors, Prostaglandin / Q000378:metabolism; D017482:Receptors, Thromboxane / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D019311:Staurosporine / Q000494:pharmacology; D013928:Thromboxane A2 / Q000378:metabolism; D014661:Vasoconstriction / Q000187:drug effects*
chemical_list: D019086:Bridged Bicyclo Compounds, Heterocyclic; D005231:Fatty Acids, Unsaturated; D005419:Flavonoids; D006834:Hydrazines; D011463:Prostaglandins H; D011982:Receptors, Prostaglandin; D017482:Receptors, Thromboxane; D044262:Prostaglandin H2; D013928:Thromboxane A2; D011189:Potassium Chloride; C040015:myricetin; C045749:SQ 29548; D011493:Protein Kinase C; D000254:Sodium-Potassium-Exchanging ATPase; D019311:Staurosporine