Togashi K, Kameya T, Kurosawa T, Hasegawa N, Kawakami M
Department of Molecular Biology, Kitasato University School of Medicine, Kanagawa, Japan.
Clin Chem. 1992 Oct;38(10):2136-9.
To develop a radioimmunoassay (RIA) specific for human C-type natriuretic peptide (hCNP), we used a highly specific antiserum raised in rabbits. Quantitative inhibition tests with various natriuretic peptides demonstrated that the 50% inhibitory dose of hCNP was 15 fmol, whereas those of other natriuretic peptides were 10(5)-fold higher, indicating a specificity satisfactory for determining concentrations of hCNP in tissues. Using this antiserum, we detected immunoreactive hCNP (ir-hCNP) in various regions of human brain and spinal cord, as well as in cerebrospinal fluid (CSF). The ir-hCNP concentrations in human neural tissues were approximately 10-fold higher than those of immunoreactive human atrial natriuretic peptide (ir-hANP). The mean (+/- SD) concentration of ir-hCNP (72.0 +/- 17.8 ng/L) in CSF also was 10-fold higher than that of ir-hANP (5.2 +/- 2.1 ng/L). Using gel-permeation chromatography, we identified two molecular forms of ir-hCNP in brain and CSF: a 2-kDa form corresponding to mature hCNP, which is composed of 22 amino acid residues (hCNP-22), and a 5- to 6-kDa form corresponding to an N-terminally extended molecule (hCNP-53). The latter form was predominant in brain; the former was the main constituent of hCNP in CSF. These results support the hypothesis that hCNP is a major natriuretic peptide, is synthesized in human brain, and functions in human central nervous tissues.
为开发一种针对人C型利钠肽（hCNP）的放射免疫分析方法（RIA），我们使用了在兔体内产生的高度特异性抗血清。用各种利钠肽进行的定量抑制试验表明，hCNP的50%抑制剂量为15飞摩尔，而其他利钠肽的该剂量则高10^5倍，这表明该方法在测定组织中hCNP浓度方面具有令人满意的特异性。使用这种抗血清，我们在人脑和脊髓的各个区域以及脑脊液（CSF）中检测到了免疫反应性hCNP（ir-hCNP）。人神经组织中ir-hCNP的浓度比免疫反应性人心房利钠肽（ir-hANP）的浓度高约10倍。脑脊液中ir-hCNP的平均（±标准差）浓度（72.0±17.8 ng/L）也比ir-hANP（5.2±2.1 ng/L）高10倍。通过凝胶渗透色谱法，我们在脑和脑脊液中鉴定出两种ir-hCNP分子形式：一种2 kDa的形式对应于成熟的hCNP，由22个氨基酸残基组成（hCNP-22），另一种5至6 kDa的形式对应于N端延伸的分子（hCNP-53）。后一种形式在脑中占主导地位；前一种形式是脑脊液中hCNP的主要成分。这些结果支持了以下假设：hCNP是一种主要的利钠肽，在人脑中合成，并在人中枢神经组织中发挥作用。
