title: Beta-adrenergic regulation of constitutive nitric oxide synthase in cardiac myocytes.
abstract: Nitric oxide (NO) has been implicated in endogenous control of myocardial contractility. However, NO release has not yet been demonstrated in cardiac myocytes. Accordingly, endogenous NO production was measured with a porphyrinic microsensor positioned on the surface of individual neonatal or adult rat ventricular myocytes (n > 6 neonatal and adult cells per experiment). In beating neonatal myocytes, there was no detectable spontaneous NO release with each contraction. However, norepinephrine (NE; 0.25-1 microM) elicited transient NO release from beating neonatal (149 +/- 11 to 767 +/- 83 nM NO) and noncontracting adult (157 +/- 13 to 791 +/- 89 nM NO) cells. NO was released by adrenergic agonists with the following rank order of potency: isoproterenol (beta1beta2) > NE (alpha/beta1) > dobutamine (beta1) approximately epinephrine (alpha/beta1beta2) > tertbutylene (beta2); NO was not released by phenylephrine (alpha). NE-evoked NO release was reversibly blocked by N(G)-monomethyl-L-arginine, trifluoperazine, guanosine 5'-O-(2-thiodiphosphate), and nifedipine but was enhanced by 3-isobutyl-1-methylxanthine (0.5 mM = 14.5 +/- 1.6%) and BAY K 8644 (10 microM = 11.9 +/- 1%). NO was also released by A-23187 (10 microM = 884 +/- 88 nM NO), guanosine 5'-O-(3-thiotriphosphate) (1 microM = 334 +/- 56 nM NO), and dibutyryl adenosine 3',5'-cyclic monophosphate (10-100 microM = 35 +/- 9 to 284 +/- 49 nM NO) but not by ATP, bradykinin, carbachol, 8-bromoguanosine 3',5'-cyclic monophosphate, or shear stress. This first functional demonstration of a constitutive NO synthase in cardiac myocytes suggests its regulation by a beta-adrenergic signaling pathway and may provide a novel mechanism for the coronary artery vasodilatation and enhanced diastolic relaxation observed with adrenergic stimulation.
authors.affiliation: Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708, USA.
authors.forename: A J
authors.initials: AJ
authors.lastname: Kanai
authors.forename: S
authors.initials: S
authors.lastname: Mesaros
authors.forename: M S
authors.initials: MS
authors.lastname: Finkel
authors.forename: C V
authors.initials: CV
authors.lastname: Oddis
authors.forename: L A
authors.initials: LA
authors.lastname: Birder
authors.forename: T
authors.initials: T
authors.lastname: Malinski
mesh_terms: D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D000375:Aging; D000818:Animals; D000831:Animals, Newborn; D003994:Bucladesine / Q000494:pharmacology; D000001:Calcimycin / Q000494:pharmacology; D002478:Cells, Cultured; D004280:Dobutamine / Q000494:pharmacology; D004790:Enzyme Induction; D006153:Guanosine Diphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D006321:Heart / Q000187:drug effects / Q000502:physiology*; D007375:Interleukin-1 / Q000494:pharmacology; D007545:Isoproterenol / Q000494:pharmacology; D009200:Myocardial Contraction / Q000187:drug effects; D009206:Myocardium / Q000166:cytology / Q000201:enzymology*; D009569:Nitric Oxide / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000096:biosynthesis*; D009638:Norepinephrine / Q000494:pharmacology; D051381:Rats; D011943:Receptors, Adrenergic, beta / Q000502:physiology*; D013726:Terbutaline / Q000494:pharmacology; D013873:Thionucleotides / Q000494:pharmacology; D014268:Trifluoperazine / Q000494:pharmacology; D019323:omega-N-Methylarginine / Q000494:pharmacology
chemical_list: D007375:Interleukin-1; D011943:Receptors, Adrenergic, beta; D013873:Thionucleotides; D006153:Guanosine Diphosphate; D014268:Trifluoperazine; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D000001:Calcimycin; D004280:Dobutamine; D003994:Bucladesine; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; C023427:guanosine 5'-O-(2-thiodiphosphate); D019001:Nitric Oxide Synthase; D007545:Isoproterenol; D013726:Terbutaline; D015056:1-Methyl-3-isobutylxanthine; D009638:Norepinephrine