Wehrwein Erica A, Parker Lindsay M, Wright Anna A, Spitsbergen John M, Novotny Martin, Babankova Dagmar, Swain Greg M, Habecker Beth A, Kreulen David L
Dept. of Physiology, Michigan State Univ., East Lansing, MI 48823, USA.
Am J Physiol Regul Integr Comp Physiol. 2008 Sep;295(3):R857-63. doi: 10.1152/ajpregu.00190.2008. Epub 2008 Jun 18.
The cardiac neuronal norepinephrine (NE) transporter (NET) in sympathetic neurons is responsible for uptake of released NE from the neuroeffector junction. The purpose of this study was to assess the chamber distribution of cardiac NET protein measured using [(3)H]nisoxetine binding in rat heart membranes and to correlate NE content to NET amount. In whole mounts of atria, NET was colocalized in nerve fibers with tyrosine hydroxylase (TH) immunoreactivity. NE content expressed as micrograms NE per gram tissue was lowest in the ventricles; however, NET binding was significantly higher in the left ventricle than the right ventricle and atria (P < 0.05), resulting in a significant negative correlation (r(2) = 0.922; P < 0.05) of NET to NE content. The neurotoxin 6-hydroxydopamine, an NET substrate, reduced NE content more in the ventricles than the atria, demonstrating functional significance of high ventricular NET binding. In summary, there is a ventricular predominance of NET binding that corresponds to a high NE reuptake capacity in the ventricles, yet negatively correlates to tissue NE content.
交感神经元中的心脏神经元去甲肾上腺素（NE）转运体（NET）负责从神经效应器连接处摄取释放的NE。本研究的目的是评估使用[³H]尼索西汀结合法测定的大鼠心脏膜中心脏NET蛋白的腔室分布，并将NE含量与NET量相关联。在心房整装片中，NET与酪氨酸羟化酶（TH）免疫反应性共定位于神经纤维中。以每克组织中微克NE表示的NE含量在心室中最低；然而，NET结合在左心室中显著高于右心室和心房（P < 0.05），导致NET与NE含量呈显著负相关（r² = 0.922；P < 0.05）。神经毒素6-羟基多巴胺是一种NET底物，其在心室中比在心房中更能降低NE含量，这表明心室中高NET结合具有功能意义。总之，NET结合在心室中占优势，这与心室中高NE再摄取能力相对应，但与组织NE含量呈负相关。
