Cohen M L, Landry A S, Hemrick S K, Fuller R W
Can J Physiol Pharmacol. 1979 Nov;57(11):1246-50. doi: 10.1139/y79-188.
The observation that the rat jugular vein relaxed in response to norepinephrine but not to field stimulation prompted us to evaluate the extent of innervation in this tissue. The norepinephrine concentration in the jugular vein was about 10% of that in the mesenteric artery and vein. The low levels of norepinephrine were not due to higher monoamine oxidase activity relative to the enzyme activity in other blood vessels. In the jugular vein, as in heart and brain, serotonin was preferred substrate for monoamine oxidase whereas in the femoral vein, mesenteric vein, and mesenteric artery, phenylethylamine oxidation was greater. Based on kinetic and inhibitory studies with LY51641, a selective type A inhibitor, monoamine oxidase activity was not found to be uniform throughout the cardiovascular system. In addition to low levels of norepinephrine, acetylcholinesterase activity in the jugular vein was only 5 and 13% of the activity in the portal vein and mesenteric artery, respectively. Thus, we provide strong evidence that our inability to generate a response to field stimulation in the rat jugular vein results from the lack of functional innervation in this tissue. This information adds to the usefulness of this preparation for comparative studies of agents acting on the smooth muscle without the added complication of neuronal uptake mechanisms.
大鼠颈静脉对去甲肾上腺素产生反应而对场刺激无反应这一观察结果促使我们评估该组织的神经支配程度。颈静脉中的去甲肾上腺素浓度约为肠系膜动脉和静脉中浓度的10%。去甲肾上腺素水平较低并非是由于相对于其他血管中的酶活性而言单胺氧化酶活性较高。与心脏和大脑一样，在颈静脉中，5-羟色胺是单胺氧化酶的首选底物，而在股静脉、肠系膜静脉和肠系膜动脉中，苯乙胺的氧化作用更强。基于对选择性A型抑制剂LY51641的动力学和抑制研究，发现单胺氧化酶活性在整个心血管系统中并不一致。除了去甲肾上腺素水平较低外，颈静脉中的乙酰胆碱酯酶活性分别仅为门静脉和肠系膜动脉中活性的5%和13%。因此，我们提供了有力证据，表明我们无法在大鼠颈静脉中对场刺激产生反应是由于该组织缺乏功能性神经支配。这一信息增加了该制剂在比较作用于平滑肌的药物时的有用性，而不会增加神经元摄取机制带来的额外复杂性。
