title: Role of nitric oxide/cyclic GMP and cyclic AMP in beta3 adrenoceptor-chronotropic response.
abstract: In this study we determine different signaling pathways involved in beta(3) adrenoceptor (beta(3)-AR) dependent frequency stimulation in isolated rodent atria. Promiscuous coupling between different G-proteins and beta(3)-AR could explain the multiple functional effects of beta(3)-AR stimulation. We examine the mechanisms and functional consequences of dual adenylate cyclase and guanylate cyclase pathways coupling to beta(3)-AR in isolated rodent atria. The beta(3)-AR selective agonists ZD 7114 and ICI 215001 stimulated in a dose-dependent manner the contraction frequency that significantly correlated with cyclic AMP (cAMP) accumulation. Inhibition of adenylate cyclase shifted the chronotropic effect to the right. On the other hand, the ZD 7114 activity on frequency was enhanced by the inhibition of nitric oxide synthase (NOS) and soluble guanylate cyclase. This countervailing negative chronotropic nitric oxide-cyclic GMP (NO-cGMP) significantly correlated with the increase on NOS activity and cGMP accumulation. Current analysis showed a negative cross talk between cAMP chronotropic and NO-cGMP effects by inhibition of phospholipase C (PLC), calcium/calmodulin (CaM), protein kinase C (PKC), NOS isoforms and Gi-protein on the effects of beta(3)-AR stimulation. RT-PCR detected both eNOS and nNOS in isolated rat atria. NOS isoforms performed independently. Only nNOS participated in limiting the effect of beta(3)-AR stimulation. In eNOS-KO (eNOS-/-) mice the chronotropic effect of beta(3)-AR agonists did not differ from wild type (WT) mice atria, but it was increased by the inhibition of nNOS activity. Our results suggest that the increase in frequency by beta(3)-AR activation on isolated rodent atria is associated to a parallel increases in cAMP. The nNOS-cGMP pathway negatively modulates beta(3)-AR activation. Multiple signal transduction pathways between G-protein and beta(3)-AR may protect myocardium from catecholamine-induced cardiotoxic effects.
authors.affiliation: Pharmacology Unit, School of Dentistry, Buenos Aires University and Argentine National Research Council (CONICET), M.T. de Alvear 2142 - 4to. "B", 1122 AAH Buenos Aires, Argentina. leo@farmaco.odon.uba.ar
authors.forename: Leonor
authors.initials: L
authors.lastname: Sterin-Borda
authors.forename: Gustavo
authors.initials: G
authors.lastname: Bernabeo
authors.forename: Sabrina
authors.initials: S
authors.lastname: Ganzinelli
authors.forename: Lilian
authors.initials: L
authors.lastname: Joensen
authors.forename: Enri
authors.initials: E
authors.lastname: Borda
mesh_terms: D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000818:Animals; D006152:Cyclic GMP / Q000378:metabolism*; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology*; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D009200:Myocardial Contraction / Q000187:drug effects / Q000502:physiology*; D009569:Nitric Oxide / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II / Q000172:deficiency / Q000378:metabolism*; D052250:Nitric Oxide Synthase Type III; D010642:Phenoxyacetates / Q000494:pharmacology; D050198:Phenoxypropanolamines / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology
chemical_list: D000318:Adrenergic beta-Agonists; D010642:Phenoxyacetates; D050198:Phenoxypropanolamines; D011943:Receptors, Adrenergic, beta; C071909:ICI D7114; C076355:ICI 215001; D009569:Nitric Oxide; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; C496315:Nos3 protein, mouse; D006152:Cyclic GMP