Wong P Y, Uchendu C N
Department of Physiology, Chinese University of Hong Kong.
J Endocrinol. 1991 Nov;131(2):287-93. doi: 10.1677/joe.0.1310287.
Monolayer cell cultures formed from the rat cauda epididymidis exhibited renin-like and angiotensin-converting enzyme (ACE) activities and contained immunoreactive angiotensin I (AI) and angiotensin II (AII). Renin-like activity, determined indirectly by radioimmunoassay of generated AI at a near-neutral pH of 6.0, was demonstrated in the cell lysate but was almost undetectable in the serum-free cell culture medium, suggesting that renin expression in epididymal cells is an intracellular phenomenon. In contrast, both AI and AII were detected in the cell lysate and cell culture medium. The level of AI was enhanced by pretreating the cells with the ACE inhibitor captopril (100 nmol/l). Incubating the cell monolayers with thoroughly washed sperm cells obtained from the intact cauda epididymides of rats increase (P less than 0.01) the AII content of the cell culture medium, with a parallel decline (P less than 0.01) in the AI concentration. However, adrenaline (0.23 mumol/l), which was found to stimulate electrogenic anion secretion by cell monolayers grown on previous supports, was without effect on the renin-like activity or concentration of angiotensins. The ACE activity in cells was confirmed by its strong dependence on chloride ion and its susceptibility to inhibition by captopril (100 nmol/l). Enzyme activity was significantly (P less than 0.005) higher in the culture medium than in the cell lysate and cell membrane fragments. Angiotensinogen, which is obligatory for an intrinsic renin-angiotensin system, is present in epididymal cells. Presumably, it is synthesized and processed in the cell cytosol by intracellular renin.(ABSTRACT TRUNCATED AT 250 WORDS)
由大鼠附睾尾部形成的单层细胞培养物表现出肾素样和血管紧张素转换酶（ACE）活性，并含有免疫反应性血管紧张素I（AI）和血管紧张素II（AII）。通过在接近中性pH值6.0时对生成的AI进行放射免疫测定间接确定的肾素样活性，在细胞裂解物中得到证实，但在无血清细胞培养基中几乎检测不到，这表明附睾细胞中的肾素表达是一种细胞内现象。相比之下，AI和AII在细胞裂解物和细胞培养基中均被检测到。用ACE抑制剂卡托普利（100 nmol/l）预处理细胞可提高AI水平。用从大鼠完整附睾尾部获得的彻底洗涤过的精子细胞孵育细胞单层，可增加（P<0.01）细胞培养基中的AII含量，同时AI浓度平行下降（P<0.01）。然而，肾上腺素（0.23 μmol/l）对肾素样活性或血管紧张素浓度没有影响，而肾上腺素被发现可刺激在先前支持物上生长的细胞单层的电生性阴离子分泌。细胞中的ACE活性通过其对氯离子的强烈依赖性及其对卡托普利（100 nmol/l）抑制的敏感性得到证实。培养基中的酶活性显著（P<0.005）高于细胞裂解物和细胞膜碎片。血管紧张素原是内在肾素-血管紧张素系统所必需的，存在于附睾细胞中。推测它是由细胞内肾素在细胞胞质溶胶中合成和加工的。（摘要截短至250字）
