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内皮素(ET)是由内皮细胞释放的一种血管收缩神经肽,它于1988年被分离。内皮素(ET_s)有三种异构肽ET_(1、2、3),均有21个氨基酸和两条二硫键。目前已确认神经组织中有ET_(-1),和ET_(-3)。人类的ET与其它哺乳动物的血管活性肠肽(VIC)结构和功能相似。ETmRNA和免疫反应性ET样物质(ET—LI)存在于人类的大脑、脊髓和脊神经节中。大脑的丘脑下部和纹状体含量最高。在脊髓后角的第Ⅳ～Ⅴ层和前角的第Ⅸ层活性最大。在人类的大脑中用~(125)Ⅰ—ET_(-1)示踪ET受体,证实它集中于灰质中。ET_3通过结合细胞表面的受体影响靶细胞。ET受体激活能触发各种细胞信使通路。在血管平滑肌细胞中,ET_(-1)刺激Ca~(+2)流入和细胞内Ca~(+2)的动员,激活磷脂酶A_2和C,蛋白激酶C和Na~+—H~+交换,诱导致癌基因C—fos的转录,并抑制Na~+—K~+—ATP酶。ET_(-1)可抑制交感神经元释放去甲肾上腺素,并刺激副交感神经元释放乙酰胆碱、匠脑下部释放加
Endothelin (ET) is a vasoconstrictive neuropeptide released by endothelial cells that was isolated in 1988. Endothelin (ET_s) has three isomeric peptides ET_ (1,2,3), both 21 amino acids and two disulfide bonds. It has been confirmed that there are ET _ (- 1), and ET _ (- 3) in nerve tissue. Human ET is structurally and functionally similar to the vasoactive intestinal peptide (VIC) of other mammals. ETmRNA and immunoreactive ET-like substances (ET-LIs) are found in the brain, spinal cord and spinal ganglia of humans. The brain of the hypothalamus and striatum content highest. In the posterior horn of the IV ~ V layer and the anterior horn of the most active layer IX. ET receptors were labeled with ~ (125) I-ET (-1) in human brains, confirming its concentration in the gray matter. ET3 affects target cells by binding to receptors on the cell surface. ET receptor activation triggers various cellular messenger pathways. In vascular smooth muscle cells, ET_ (-1) stimulated Ca ~ (+2) influx and intracellular Ca ~ (+2) mobilization, activating phospholipase A_2 and C, protein kinase C and Na ~ + -H ~ + exchange , Induces transcription of the oncogene C-fos and inhibits Na ~ + -K ~ + -ATPase. ET_ (-1) inhibits the release of norepinephrine from sympathetic neurons and stimulates the release of acetylcholine from parasympathetic neurons