人肾心钠素降解酶的分布及心钠素降解抑制的研究

Distribution of atrial natriuretic factor (ANF) degrading enzyme in human kidneys and inhibition of ANF degradation

将人肾分为外皮质（ＯＣ）、内皮质（ＩＣ）、外带（ＯＳ）、内带（ＩＳ）、和内髓质（ＩＭ）五个区带，运用荧光法和放免法，对中性肽链内切酶（ＮＥＰ）高度特异的合成代用底物［丹酰－丙氨酰－甘氨酰－对硝基苯丙氨酰－甘氨酸（ＤＡＧＮＰＧ）］和天然底物心钠素研究心钠素降解酶在各区带的分布及心钠素降解的抑制。结果表明：人肾心钠素降解酶的分布，在各区带有所不同，以ＯＣ最高，ＩＭ最低，降解酶活性依次为ＯＣ＞ＩＣ＞ＯＳ＞ＩＳ＞ＩＭ，提示该酶对心钠素的降解主要发生在肾小球和近端小管。抑制实验表明，黄豆胰蛋白酶抑制剂和水稻丝氨酸蛋白酶抑制剂均能有效抑制人肾对ＤＡＧＮＰＧ和心钠素的降解，黄豆胰蛋白酶抑制剂的抑制率分别为７５．７％和７２．０％，水稻丝氨酸蛋白酶抑制剂的抑制率分别为７５．３％和７４．７％。

Human kidneys were separated into five regions inclusing outer cortex (OC), inner cortex (IC), outer stripe(OS), inner stripe (IS) and inner medulla(IM). The regional distribution of atrial natriuretic factor (ANF) degrading enzyme and the inhibition of ANF degradation were investigated by an enzymatic fluorometric method employing N dansyl D alanyl glycyl L 4 nitrophenylalanyl glycine(DAGNPG) as a synthetic surrogate a highly specific substrate to neutral endopeptidase (NEP) and radioimmunoassay (RIA) using atrial natriuretic factor (ANF) as a natural substrate to NEP. The results showed that there was different regional distribution of ANF degrading enzyme in human kidneys. OC had the highest activity of ANF degrading enzyme, and IM had the lowest activity. The sequence of activity of degrading enzyme was OC >IC >OS >IS >IM. These results suggested that the degradation of ANF by ANF degrading enzyme occured mainly in the glomerulus and the proximal tubules. The inhibitory tests showed that both soybean trypsin inhibitor and rice serine protease inhibitor could effectively inhibit the degradation of DAGNPG and ANF in human kideny, The inhibitory rate are 75.58% and 72.04% for soybean trypsin inhibitor, 75.21% and 74.65% for rice serine protease inhibitor, respectively.