title: Combined contribution of endothelial relaxing autacoides in the rat femoral artery response to CPCA: an adenosine A2 receptor agonist.
abstract: We examined the contribution of endothelial relaxing factors and potassium channels in actions of CPCA, potent adenosine A(2) receptor agonist, on isolated intact male rat femoral artery (FA). CPCA produced concentration-dependent relaxation of FA, which was notably, but not completely, reduced after endothelial denudation. DPCPX, A(1) receptor antagonist, had no significant effect, while SCH 58261 (A(2A) receptor antagonist) notably reduced CPCA-evoked effect. Pharmacological inhibition of nitric oxide synthase or cyclooxygenase comparably reduced CPCA-evoked action, still in a lesser degree than after denudation. In the presence of buffer with high K(+) (100  mM), CPCA-produced relaxations were almost abolished. TEA (nonselective K(Ca) blocker), glibenclamide (K(ATP) blocker), Ba(++) (K(IR) blocker), or ouabain (Na(+)/K(+)-ATPase inhibitor) did not change CPCA-induced relaxation. Concentration-response curve for CPCA was significantly shifted to the right after the incubation of apamin (SK channel blocker). CPCA produced concentration-dependent relaxation of FA that was partly dependent on endothelial cells. Endothelium-related portion of CPCA-elicited effect was mediated by combined action of endothelial NO, prostacyclin, and EDHF after activation of endothelial A(2A) receptors. Small conductance K(Ca) channels were involved in this action.
authors.affiliation: Department of Pharmacology, Clinical Pharmacology and Toxicology, School of Medicine, University of Belgrade, P.O. Box 38, 11129 Belgrade, Serbia. mradenkovic@med.bg.ac.rs
authors.forename: Miroslav
authors.initials: M
authors.lastname: Radenković
authors.forename: Marko
authors.initials: M
authors.lastname: Stojanović
authors.forename: Radmila
authors.initials: R
authors.lastname: Janković
authors.forename: Mirko
authors.initials: M
authors.lastname: Topalović
authors.forename: Milica
authors.initials: M
authors.lastname: Stojiljković
mesh_terms: D000241:Adenosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D058908:Adenosine A2 Receptor Agonists / Q000494:pharmacology*; D000818:Animals; D012898:Autacoids / Q000502:physiology*; D005263:Femoral Artery / Q000187:drug effects* / Q000502:physiology; D009126:Muscle Relaxation / Q000502:physiology; D051381:Rats; D043683:Receptors, Adenosine A2 / Q000187:drug effects*
chemical_list: D058908:Adenosine A2 Receptor Agonists; D012898:Autacoids; D043683:Receptors, Adenosine A2; C024311:N-cyclopropyl adenosine-5'-carboxamide; D000241:Adenosine