Development of angiotensin-converting enzyme in fetal rat lungs.
Development of angiotensin-converting enzyme in fetal rat lungs.
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胎鼠肺中血管紧张素转换酶的发育。
DOI：
10.1152/ajpregu.1979.236.1.r57
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发表时间：
1979
期刊：
影响因子：
--
通讯作者：
J. Hook
中科院分区：
文献类型：
--
作者：
K. Wallace;M. Bailie;J. Hook
血管紧张素转换酶（ACE）催化血管紧张素I快速水解形成血管紧张素II（AII）。由于转化酶活性在出生时就存在，出生后增加到成人值，因此确定ACE的产前发育是有意义的。使用马尿酰-L-组氨酰-L-亮氨酸（HHL）作为底物，在肺匀浆的20，000 x g上清液部分中测定转化酶活性。HHL水解释放的马尿酸用荧光定量法定量。ACE活性在妊娠18天首次检测到，并在出生前（妊娠21天）增加了4倍。肺ACE活性的1日龄动物的两倍，胎儿在妊娠第20天，但是，这种增加似乎并不导致单独的通气。胎儿ACE（2.0 mM HHL）的Michaelis-Menten常数与成年大鼠肺ACE（2.6 mM）的计算值无差异。这些数据被解释为表明与年龄相关的ACE活性增加是由于更大的ACE含量，而不是进一步激活预先存在的酶。这种胎儿ACE活性的增加可能在为出生后功能准备肾素-血管紧张素系统中发挥重要作用。
Angiotensin-converting enzyme (ACE) catalyzes rapid hydrolytic cleavage of angiotensin I to form angiotensin II (AII). Inasmuch as converting enzyme activity is present at birth and increases postnatally to adult values it was of interest to determine the prenatal development of ACE. Converting enzyme activity was determined in the 20,000 x g supernatant fraction of lung homogenates using hippuryl-L-histidyl-L-leucine (HHL) as substrate. Hippuric acid liberated by the hydrolysis of HHL was quantified spectrophotometrically. ACE activity was first detectable at 18 days of gestation and increased fourfold prior to birth (21 days gestation). Pulmonary ACE activity of 1-day-old animals was twice that of fetuses at day 20 of gestation; however, this increase did not appear to result from ventilation alone. The Michaelis-Menten constant for fetal ACE (2.0 mM HHL) was not different from that calculated for ACE of adult rat lungs (2.6 mM). These data were interpreted to indicate that the age-related increase in ACE activity was due to greater ACE content as opposed to further activation of preexisting enzyme. This increase in fetal ACE activity may play an important role in preparing the renin-angiotensin system for postnatal function.