Beta3-adrenergic eNOS stimulation in left ventricular murine myocardium.
This study investigates mechanisms underlying beta3-adrenergic activation of the endothelial nitric oxide synthase (eNOS) in myocardial tissue of wild-type (WT) and beta3-adrenoceptor knockout (beta3-KNO) mice, in the absence and presence of BRL 37344 (BRL), the preferential beta3-adrenoceptor selective agonist. Nitric oxide (NO)-liberation was measured after the application of BRL (10 micromol/L), using fluorescence dye diaminofluorescein (DAF), in left ventricular cardiac preparations. Phosphorylation of eNOSSer1177, eNOSThr495, eNOSSer114, and eNOS translocation, and alterations of 8-isoprostaglandin F2alpha (a parameter for reactive oxygen radical generation), after application of BRL (10 micromol/L), were studied using immunohistochemical stainings in isolated, electrically stimulated (1 Hz) right atrial (RA) and left ventricular (LV) myocardium. An increased NO release after BRL application (10 micromol/L) was observed in the RA and LV myocardial tissue of WT mice, but not in beta3-KNO mice. This NO liberation in WT mice was paralleled by an increased eNOSSer1177, but not eNOSThr495, phosphorylation. A cytosolic eNOS translocation was observed after the application of BRL (10 micromol/L) only in the RA myocardial tissue of WT mice. A BRL (10 micromol/L)-dependent increase in eNOSSer114 phosphorylation was observed only in the LV myocardial tissue of WT mice; this was paralleled by an increase in 8-isoprostaglandin F2alpha. In murine myocardium, 3 beta3-adrenoceptor-dependent activation pathways for eNOS exist (i.e., a translocation and phosphorylation of eNOSSer1177 and eNOSSer114). These pathways are used in a regional-dependent manner. beta3-adrenergic oxygen-derived free radical production might be important in situations of enhanced beta3-adrenoceptor activation, as has been described in human heart failure.
Brixius
Klara
K
Laboratory of Muscle Research and Molecular Cardiology, Department of Internal Medicine III, University of Cologne, Germany.
Bloch
Wilhelm
W
Ziskoven
Christoph
C
Bölck
Birgit
B
Napp
Andreas
A
Pott
Christian
C
Steinritz
Dirk
D
Jiminez
Maria
M
Addicks
Klaus
K
Giacobino
Jean-Paul
JP
Schwinger
Robert H G
RH
D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000818:Animals; D002462:Cell Membrane / Q000502:physiology; D004983:Ethanolamines / Q000494:pharmacology; D019793:Fluorescein / Q000494:pharmacology; D005609:Free Radicals / Q000378:metabolism; D006321:Heart / Q000294:innervation*; D015151:Immunoblotting; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D009206:Myocardium / Q000201:enzymology*; D009569:Nitric Oxide / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000502:physiology*; D010766:Phosphorylation; D021381:Protein Transport; D018342:Receptors, Adrenergic, beta-1 / Q000378:metabolism; D018343:Receptors, Adrenergic, beta-2 / Q000378:metabolism; D022702:Receptors, Adrenergic, beta-3 / Q000235:genetics / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology; D016707:Tissue Fixation; D016276:Ventricular Function
C111205:4,5-diaminofluorescein; D000318:Adrenergic beta-Agonists; D004983:Ethanolamines; D005609:Free Radicals; D018342:Receptors, Adrenergic, beta-1; D018343:Receptors, Adrenergic, beta-2; D022702:Receptors, Adrenergic, beta-3; D009569:Nitric Oxide; C057368:BRL 37344; D052250:Nitric Oxide Synthase Type III; D019793:Fluorescein