动脉壁脑啡肽的含量,存在部位及作用途径

用放射免疫法测得兔动脉的亮氨酸脑啡肽(L-ENK)和甲硫氨酸脑啡肽(M-ENK)样免疫活性物的含量(pg/mg组织湿重)分别为耳动脉38.99±17.29,134.67±8.11;肾动脉31.10±7.76,93.60±18.22,肠系膜动脉25.70 13.60,88.43±18.16。动物经注射交感神经末梢化学切割剂6-OHDA后,这三种动脉中L-ENK样免疫活性物的含量均明显下降(P<0.001);切除颈上神经节使支配耳动脉的交感神经溃变后,或离体耳动脉条受电场刺激后,脑啡肽(ENK)样免疫活性物的含量也都显著下降(P<0.001);但注射利血平则无明显影响,用荧光法测定培育动脉条的浴槽液中NE的含量,观察到ENK可抑制电场刺激所引起的NE的释放。结果提示,动脉壁的L-ENK和M-ENK存在于交感神经末梢中,它可因受电场刺激而释放,可能通过激活突触前膜阿片受体,减少交感神经末梢释放NE,从而抑制动脉的收缩活动。

CONTENT, LOCATION AND ACTION SITE OF ENKEPHALINS IN ARTERIAL WALLS

Contents of L-enkephalin (L-ENK) and M-enkephalin (M-ENK) in arteries of rabbit were measured by radioimmunoassay. Mean values of L-ENK and M-ENK (pg/mg of wet tissue) were 38.99 +/- 17.29 and 134.67 +/- 8.11 in the rabbit ear artery; 31.10 +/- 7.76 and 93.60 +/- 18.22 in the renal artery; 25.70 +/- 13.60 and 88.43 +/- 18.16 in the mesenteric artery, respectively. L-ENK in these arteries decreased significantly (P less than 0.001) after chemicosympathectomy by injection of 6-OHDA; ENK in the ear artery were reduced significantly (P less than 0.001) following the excision of the superior cervical ganglion or electrical-field stimulation, but not changed after injection of reserpine. Content of NE in the artery strip bath medium was measured by fluorimetric assay. NE in the medium was decreased significantly after administration of L-ENK or M-ENK. The results suggest that enkephalins may exist in the sympathetic nerve terminals innervating arterial walls and may be released by electrical-field stimulation. Enkephalins inhibit the contracting activity of artery strips probably by decreasing the release of NE from sympathetic nerve endings.