Rorie D K, Tyce G M
Am J Physiol. 1982 Feb;242(2):H233-9. doi: 10.1152/ajpheart.1982.242.2.H233.
The overflow of endogenous norepinephrine (NE) from superfused dog pulmonary artery and saphenous vein in response to electrical stimulation and the content of NE remaining in the tissue after stimulation were measured using liquid chromatography with electrochemical detection. Overflow of NE was 0.15-0.22 and 0.14 to 0.30 ng/min in pulmonary artery and saphenous vein, respectively, during stimulation. Release of NE (measured in the presence of cocaine and corticosterone to block removal of NE from the synaptic cleft) was greater in the pulmonary artery (0.50-0.87 ng/min) than in saphenous vein (0.39-0.51 ng/min). NE overflow decreased after the first 4 min of continuous stimulation in saphenous vein but not in pulmonary artery. As only 2.26% of the NE content of vein overflowed during stimulation, depletion of NE or deterioration of the preparation seemed unlikely. Presynaptic alpha- or beta-receptor blockade did not change the pattern of NE overflow. Thus in the saphenous vein, but not in the pulmonary artery, removal of NE from the synaptic cleft appears to be facilitated during electric stimulation. This suggests the existence of a new mechanism, possibly related to enhanced catechol methyltransferase activity, which regulates NE levels in the synaptic cleft in saphenous vein but not in pulmonary artery.
使用带有电化学检测的液相色谱法，测量了电刺激下犬肺动脉和隐静脉中内源性去甲肾上腺素（NE）的溢出量以及刺激后组织中剩余的NE含量。刺激期间，肺动脉和隐静脉中NE的溢出量分别为0.15 - 0.22和0.14至0.30 ng/分钟。在存在可卡因和皮质酮以阻止NE从突触间隙清除的情况下测量的NE释放量，肺动脉（0.50 - 0.87 ng/分钟）比隐静脉（0.39 - 0.51 ng/分钟）更大。在隐静脉中持续刺激的前4分钟后NE溢出量减少，但在肺动脉中未减少。由于刺激期间静脉中仅2.26%的NE含量溢出，NE耗竭或制剂恶化似乎不太可能。突触前α或β受体阻断并未改变NE溢出模式。因此，在隐静脉而非肺动脉中，电刺激期间似乎促进了NE从突触间隙的清除。这表明存在一种新机制，可能与儿茶酚甲基转移酶活性增强有关，该机制调节隐静脉而非肺动脉中突触间隙的NE水平。
