Brixius Klara, Bloch Wilhelm, Ziskoven Christoph, Bölck Birgit, Napp Andreas, Pott Christian, Steinritz Dirk, Jiminez Maria, Addicks Klaus, Giacobino Jean-Paul, Schwinger Robert H G
Laboratory of Muscle Research and Molecular Cardiology, Department of Internal Medicine III, University of Cologne, Germany.
Can J Physiol Pharmacol. 2006 Oct;84(10):1051-60. doi: 10.1139/y06-033.
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.
本研究调查了在野生型（WT）和β3-肾上腺素能受体基因敲除（β3-KNO）小鼠的心肌组织中，在不存在和存在优先的β3-肾上腺素能受体选择性激动剂BRL 37344（BRL）的情况下，β3-肾上腺素能激活内皮型一氧化氮合酶（eNOS）的潜在机制。在左心室心脏制剂中，使用荧光染料二氨基荧光素（DAF），在应用BRL（10微摩尔/升）后测量一氧化氮（NO）释放。应用BRL（10微摩尔/升）后，使用免疫组织化学染色法，在分离的、电刺激（1赫兹）的右心房（RA）和左心室（LV）心肌中，研究eNOSSer1177、eNOSThr495、eNOSSer114的磷酸化、eNOS易位以及8-异前列腺素F2α（活性氧自由基生成参数）的变化。在WT小鼠的RA和LV心肌组织中，观察到应用BRL（10微摩尔/升）后NO释放增加，但在β3-KNO小鼠中未观察到。WT小鼠中的这种NO释放增加与eNOSSer1177磷酸化增加平行，但与eNOSThr495磷酸化无关。仅在WT小鼠的RA心肌组织中，应用BRL（10微摩尔/升）后观察到胞质eNOS易位。仅在WT小鼠的LV心肌组织中观察到BRL（10微摩尔/升）依赖性的eNOSSer114磷酸化增加；这与8-异前列腺素F2α增加平行。在鼠心肌中，存在3种β3-肾上腺素能受体依赖性的eNOS激活途径（即eNOSSer1177和eNOSSer114的易位和磷酸化）。这些途径以区域依赖性方式使用。如在人类心力衰竭中所描述的，β3-肾上腺素能氧衍生的自由基产生在β3-肾上腺素能受体激活增强的情况下可能很重要。
