Janas Roman M, Janas Jadwiga, Warnawin Krzysztof, Szalecki Mieczysław
Department of Radioimmunology, The Children's Memorial Health Institute, Al. Dzieci Polskich 20, 04-736 Warsaw, Poland.
Regul Pept. 2008 Nov 29;151(1-3):7-13. doi: 10.1016/j.regpep.2008.08.004. Epub 2008 Sep 5.
Endothelin-1 is involved in physiology and pathophysiology of the alimentary tract. The peptide modulates blood flow in the gastrointestinal microvasculature and regulates contractility of smooth muscles and, when present in excess, may be an important factor contributing to pathogenesis of various forms of mucosal injury and peristaltic disorders. Mechanisms that regulate endothelin concentration in the gastrointestinal tissues are unknown. Therefore, the aim of our study was to identify and characterize endothelin inactivating peptidases in the rat gastrointestinal mucosa and smooth muscle cells. We have found three high affinity and efficient endothelin-1 inactivating peptidases. The acidic (pH optimum 5.5), membrane-bound, thiorphan- (ED(50) 1.2+/-0.2 nM) and phosphoramidon (ED(50) 150+/-25 pM) sensitive, endothelin-1 inactivating peptidase (K(M) 0.12+/-0.03 microM) was present in the mucosal cells of duodenum and small intestine. The enzyme exhibited high molecular weight (>100 kDa) and characteristics similar to that of the rat and human kidney, acidic metalloendopeptidase that was recently described. Two forms of the unique, low molecular weight (100>MW>30 kDa), alkaline (pH optimum 8.5), specific (K(M) 0.5+/-0.2 microM), thiorphan- and phosphoramidon insensitive, 1,10 phenanthroline inhibitable (ED(50) 0.65+/-0.20 mM, mean+/-S.E.M.) endothelin-1 inactivating peptidase were present exclusively in the duodenal mucosal cells; soluble form in cytosol and membrane-bound form exhibiting an abundance ratio 5:1, respectively. Mucosa of the stomach and large intestine, and gastrointestinal smooth muscle cells do not contain the specific endothelin-1 inactivating peptidases. The enzymes may play a crucial role in regulation of endothelin concentration in the gastrointestinal tissues. Whether impairment of activity of the mucosal endothelin inactivating peptidases, resulting in the increase of concentration of endothelin peptides in gastrointestinal tissues, occurs in various pathological conditions is actually studied in our laboratory.
内皮素 -1参与消化道的生理和病理生理过程。该肽调节胃肠道微血管中的血流并调节平滑肌的收缩性，并且当过量存在时，可能是导致各种形式的粘膜损伤和蠕动障碍发病机制的重要因素。调节胃肠道组织中内皮素浓度的机制尚不清楚。因此，我们研究的目的是鉴定和表征大鼠胃肠道粘膜和平滑肌细胞中的内皮素失活肽酶。我们发现了三种高亲和力且高效的内皮素 -1失活肽酶。酸性（最适pH 5.5）、膜结合、对硫磷酰胺（ED50 1.2±0.2 nM）和磷酰胺（ED50 150±25 pM）敏感的内皮素 -1失活肽酶（Km 0.12±0.03 μM）存在于十二指肠和小肠的粘膜细胞中。该酶表现出高分子量（>100 kDa），其特性与最近描述的大鼠和人肾脏酸性金属内肽酶相似。两种独特的低分子量（100>MW>30 kDa）、碱性（最适pH 8.5）、特异性（Km 0.5±0.2 μM）、对硫磷酰胺和磷酰胺不敏感、1,10 - 菲咯啉可抑制（ED50 0.65±0.20 mM，平均值±标准误）的内皮素 -1失活肽酶仅存在于十二指肠粘膜细胞中；可溶形式存在于胞质溶胶中，膜结合形式的丰度比分别为5:1。胃和大肠的粘膜以及胃肠道平滑肌细胞不含特异性内皮素 -1失活肽酶。这些酶可能在调节胃肠道组织中内皮素浓度方面起关键作用。我们实验室正在实际研究在各种病理条件下，粘膜内皮素失活肽酶的活性受损是否会导致胃肠道组织中内皮素肽浓度增加。
