Vindrola O, Ase A, Finkielman S, Nahmod V E
Sección Sustancias Vasoactivas, Instituto de Investigaciones Médicas, Buenos Aires, Argentina.
J Neurochem. 1988 Feb;50(2):424-30. doi: 10.1111/j.1471-4159.1988.tb02929.x.
We have compared the enkephalin-like material derived from proenkephalin released from perfused cat adrenal glands stimulated with pilocarpine (5 X 10(-4)M) and nicotine (5 X 10(-6) M). In addition, two doses of acetylcholine (10(-5) and 10(-4) M) and 50 mM K+ were tested. Free Met-enkephalin immunoreactivity and total Met-enkephalin immunoreactivity, as determined by enzymatic digestion of large enkephalin-containing fragments, were coreleased with catecholamines. Free Met-enkephalin immunoreactivity represented 13% of total immunoreactivity for nicotinic stimulation, 46% for pilocarpine, 33% for 10(-5) M acetylcholine, 22% for 10(-4) M acetylcholine, and 16% for 50 mM K+. Analysis of the perfusate by gel filtration showed that 80% of the total Met-enkephalin immunoreactivity whose release was induced by pilocarpine was eluted in fractions corresponding to fragments of low molecular weight, whereas these fractions accounted only for 10% of the total Met-enkephalin immunoreactivity whose release was induced by nicotine. HPLC analysis of low-molecular-weight peptide fractions revealed that Met-enkephalin, Met-enkephalin-Arg-Gly-Leu, and Met-enkephalin-Arg-Phe represented 69% of total Met-enkephalin immunoreactivity whose release was induced by pilocarpine. These results indicate that selective activation of muscarinic receptors is followed by release of low-molecular-weight material, whereas nicotine application also yielded high-molecular-weight peptides. Furthermore, increasing the acetylcholine concentration from 10(-5) to 10(-4) M and using 50 mM K+ increased proportionally the high-molecular-weight peptide secretion. Results are discussed in relation to the existence of a heterogeneous population of granules either in the same cell or in different cells, containing proenkephalin-derived peptides. (ABSTRACT TRUNCATED AT 250 WORDS)
我们比较了用毛果芸香碱（5×10⁻⁴M）和尼古丁（5×10⁻⁶M）刺激的灌注猫肾上腺释放的源自前脑啡肽的脑啡肽样物质。此外，还测试了两剂乙酰胆碱（10⁻⁵和10⁻⁴M）和50mM K⁺。通过对含脑啡肽大片段的酶消化测定的游离甲硫氨酸脑啡肽免疫反应性和总甲硫氨酸脑啡肽免疫反应性与儿茶酚胺共同释放。游离甲硫氨酸脑啡肽免疫反应性在烟碱刺激下占总免疫反应性的13%，毛果芸香碱刺激下占46%，10⁻⁵M乙酰胆碱刺激下占33%，10⁻⁴M乙酰胆碱刺激下占22%，50mM K⁺刺激下占16%。通过凝胶过滤对灌注液进行分析表明，毛果芸香碱诱导释放的总甲硫氨酸脑啡肽免疫反应性的80%在对应于低分子量片段的级分中洗脱，而这些级分仅占尼古丁诱导释放的总甲硫氨酸脑啡肽免疫反应性的10%。对低分子量肽级分的HPLC分析显示，甲硫氨酸脑啡肽、甲硫氨酸脑啡肽-精氨酸-甘氨酸-亮氨酸和甲硫氨酸脑啡肽-精氨酸-苯丙氨酸在毛果芸香碱诱导释放的总甲硫氨酸脑啡肽免疫反应性中占69%。这些结果表明，毒蕈碱受体的选择性激活之后是低分子量物质的释放，而应用尼古丁也产生高分子量肽。此外，将乙酰胆碱浓度从10⁻⁵M增加到10⁻⁴M以及使用50mM K⁺会使高分子量肽的分泌成比例增加。结合同一细胞或不同细胞中存在含有源自前脑啡肽的肽的异质颗粒群体对结果进行了讨论。（摘要截断于250字）
