Gomez-Sanchez C E, Cozza E N, Foecking M F, Chiou S, Ferris M W
Department of Internal Medicine, University of South Florida Health Sciences Center, Tampa.
Hypertension. 1990 Jun;15(6 Pt 2):744-7. doi: 10.1161/01.hyp.15.6.744.
Endothelins (ETs) are 21-amino acid peptides with two disulfide bonds that have powerful vasoactive properties. We have previously shown the presence of a specific, high-affinity, saturable receptor for porcine or human endothelin (ET-1) in cultured calf zona glomerulosa cells. ET-1 was a stimulator of aldosterone secretion although not as powerful as angiotensin II. Incubations of cultured calf zona glomerulosa cells with Sarafotoxin S6b (S6b), a snake venom that has a structure highly homologous to ET-1, stimulated aldosterone secretion with a potency similar to that of ET-1. Binding of [125I]ET-1 to the adrenal receptor gave a Kd of 0.17 +/- 0.05 nM and a Bmax of 36 +/- 8.5 fmol/well (n = 4). Displacement of [125I]ET-1 by unlabeled ETs and S6b showed that the concentrations needed to displace 50% of the tracer were 0.3 nM for ET-1, 0.3 nM for ET-2, 10 nM for S6b, and 100 nM for ET-3. Binding of [125I]S6b to cultured adrenal cells revealed a receptor with a Kd of 0.05 +/- 0.01 nM and a Bmax of 8 +/- 2 fmol/well (n = 4). Displacement of [125I]S6b by unlabeled ETs and S6b showed that the concentrations needed to displace 50% of the tracer were 0.03 nM for S6b, 0.06 nM for ET-1, 0.04 nM for ET-2, and 0.05 nM for ET-3. Unlabeled ET-1 and ET-2 preferentially down-regulated the binding of [125I]ET-1, and S6b preferentially down-regulated the binding of [125I]S6b.(ABSTRACT TRUNCATED AT 250 WORDS)
内皮素（ETs）是一种含有两个二硫键的21个氨基酸的肽，具有强大的血管活性特性。我们之前已经证明，在培养的小牛肾小球带细胞中存在一种特异性、高亲和力、可饱和的猪或人内皮素（ET-1）受体。ET-1是醛固酮分泌的刺激物，尽管其作用不如血管紧张素II强大。用与ET-1结构高度同源的蛇毒沙拉毒素S6b（S6b）孵育培养的小牛肾小球带细胞，可刺激醛固酮分泌，其效力与ET-1相似。[125I]ET-1与肾上腺受体的结合，解离常数（Kd）为0.17±0.05 nM，最大结合容量（Bmax）为36±8.5 fmol/孔（n = 4）。未标记的ETs和S6b对[125I]ET-1的置换显示，置换50%示踪剂所需的浓度，ET-1为0.3 nM，ET-2为0.3 nM，S6b为10 nM，ET-3为100 nM。[125I]S6b与培养的肾上腺细胞的结合显示，受体的Kd为0.05±0.01 nM，Bmax为8±2 fmol/孔（n = 4）。未标记的ETs和S6b对[125I]S6b的置换显示，置换50%示踪剂所需的浓度，S6b为0.03 nM，ET-1为0.06 nM，ET-2为0.04 nM，ET-3为0.05 nM。未标记的ET-1和ET-2优先下调[125I]ET-1的结合，而S6b优先下调[125I]S6b的结合。（摘要截短于250字）
