Distribution and physiological function of atrial and brain natriuretic peptides in lower vertebrates.

1. 心房和脑利钠肽（ANP， BNP）。(1)采用全身放射自显影法研究了ANP结合位点在medaka腹腔注射[^<125>I]-大鼠ANP的分布。在鳃中发现了高水平的放射性物质。ANP可能作用于鳃，起到调节鱼体内水盐平衡等作用。(2)通过双免疫金标记，发现ANP和BNP共存于所有脊椎动物类别的代表性动物（硬骨鱼和两栖动物各2种，爬行动物、鸟类和哺乳动物各1种）心房和心室心肌细胞的同一分泌颗粒中。在大多数动物中，ANP的免疫反应性强于BNP，而medaka和软壳龟的免疫反应性则相反。这两种肽可能同时分泌到循环中，发挥一些协调的功能。(3)在饮水充足的日本鹌鹑中，猪脑钠肽可引起水摄入量的显著增加，分别腹腔注射（5和10马克杯/只）或脑室注射（0.3马克杯/只）。BNP可能作用于大脑刺激饮酒行为。内皮素（ET）(1)采用放射免疫法测定了非哺乳动物（环口动物、板鳃动物、两栖动物、爬行动物和鸟类各1种，硬骨鱼2种）血浆中的免疫反应性ET。所有动物的免疫反应性ET-1水平与人类相似（平均值：3.3-9.6 pg/ml），除了盲鳗的水平相当低（0.7 pg/ml）。这些结果表明该肽在这些物种中具有内分泌功能。(2)在所有脊椎动物纲的代表性动物的下丘脑-下丘脑系统中均发现免疫反应性ET-1。此外，双免疫金标记显示，免疫反应性ET-1在大鼠抗利尿激素和催产素轴突分泌颗粒中分别与神经垂体激素共存。

1. Atrial and brain natriuretic peptides (ANP, BNP).(1) The distribution of binding sites for ANP was studied by whole-body autoradiography in medaka, which was injected [ ^<125>I]-rat ANP intraperitoneally. High levels of radioactivity were found in the gill. ANP may act on the gill and play some roles, such as regulation of water and salt balance in fish. (2) By the double immunogold labeling, it was found that ANP and BNP coexist in the same secretory granules of atrial and ventricular cardiocytes in the representative animals of all vertebrate classes (two species each of teleosts and amphibians, and one species each of reptiles, birds and mammals). In most of animals examined, the immunoreactivity for ANP was stronger than that for BNP, but the opposite was true in the medaka and the soft-shelled turtle. Both peptides may be secreted simultaneously into circulation to play some coordinated functions. (3) Porcine BNP elicited a significant increase in water intake, when administered intraperitoneally (5 and 10 mug/bird) or intracerebroventricularly (0.3 mug/birds) in the water-replete Japanese quail. BNP may act on the brain to stimulatd drinking behavior.2. Endothelin (ET)(1) Immunoreactive ET was estimated in plasma of nonmammalian vertebrates (one species each of cyclostomes, elasmobranchs, amphibians, reptiles and birds and two species of teleosts, employing radioimmunoassay for ET-1. Levels of immunoreactive ET-1 were similar to those of human in all animals (mean : 3.3-9.6 pg/ml), except that it was rather low in the hagfish (0.7 pg/ml). These results suggest an endocrine function of the peptide in these species. (2) Immunoreactive ET-1 was found in the hypothalamo-hypophysial system of the representative animals of all vertebrate classes. Further, the double immunogold labeling revealed in rats that immunoreactive ET-1 coexisted with neurohypophysial hormones in the secretory granules of the vasopressinergic and oxytocinergic axons, respectively.