Sharif N A, Xu S X
Molecular Pharmacology Unit, Alcon Laboratories, Inc., Fort Worth, TX 76134, USA.
Exp Eye Res. 1996 Dec;63(6):631-7. doi: 10.1006/exer.1996.0157.
This study sought to pharmacologically characterize bradykinin receptors on SV40-immortalized human trabecular meshwork (HTM3) cells. Phosphoinositide (PI) turnover studies were conducted using [3H]myo-inositol-labeled HTM3 cells and anion exchange chromatography to quantify [3H]inositol phosphates generated in response to bradykinin (BK) and various BK analogs. The blockade of these responses was studied using two potent and receptor-subtype selective antagonists. BK and T-kinin (Ile-Ser-BK:TK) induced a 4.2-4.4 fold stimulation of PI turnover above base levels at 1-10 microM. Several other peptides unrelated to BK, including angiotensin II, endothelin, cholecystokinin, bombesin and peptide YY tested at 1-10 microM were essentially inactive. The molar potencies (EC50) of BK, TK and close analogs were: BK = 4.5 +/- 0.5 nM (n = 6), Lys-BK = 6.5 +/- 0.7 nM (n = 3), TK = 38.8 +/- 6.6 nM (n = 8), Met-Lys-BK = 41.5 +/- 13.4 nM (n = 4), Des-Arg9-BK = 2093 +/- 626 nM (n = 4). All the latter BK-related peptides were full agonists. The actions of BK and TK were potently and competitively antagonized by Hoe-140 (molar potency = 0.6-1 nM; pA2 = 8.97-9.21. n = 3-4) and by D-Arg0[Hyp3,-Thi5.8,-DPhe7]-BK (molar potency = 251 nM; -log potency, pKb = 6.6), two selective B2-type BK antagonists. In conclusion, rank order of potency of BK agonists and the blockade of BK- and TK-induced PI turnover by the selective antagonists are consistent with the classification of the BK receptors on HTM3 cells as the B2-receptor subtype.
本研究旨在从药理学角度对SV40永生化人小梁网（HTM3）细胞上的缓激肽受体进行表征。使用[3H]肌醇标记的HTM3细胞和阴离子交换色谱法进行磷酸肌醇（PI）周转研究，以量化缓激肽（BK）和各种BK类似物刺激产生的[3H]肌醇磷酸。使用两种强效且受体亚型选择性拮抗剂研究这些反应的阻断情况。BK和T-激肽（Ile-Ser-BK：TK）在1-10 microM时可诱导PI周转比基础水平增加4.2-4.4倍。在1-10 microM测试的其他几种与BK无关的肽，包括血管紧张素II、内皮素、胆囊收缩素、蛙皮素和肽YY，基本无活性。BK、TK及相近类似物的摩尔效价（EC50）分别为：BK = 4.5 +/- 0.5 nM（n = 6），Lys-BK = 6.5 +/- 0.7 nM（n = 3），TK = 38.8 +/- 6.6 nM（n = 8），Met-Lys-BK = 41.5 +/- 13.4 nM（n = 4），Des-Arg9-BK = 2093 +/- 626 nM（n = 4）。所有后几种与BK相关的肽均为完全激动剂。BK和TK的作用被Hoe-140（摩尔效价 = 0.6-1 nM；pA2 = 8.97-9.21，n = 3-4）和D-Arg0[Hyp3,-Thi5.8,-DPhe7]-BK（摩尔效价 = 251 nM；-log效价，pKb = 6.6）强效竞争性拮抗，这两种是选择性B2型BK拮抗剂。总之，BK激动剂的效价顺序以及选择性拮抗剂对BK和TK诱导的PI周转的阻断作用与HTM3细胞上的BK受体分类为B2受体亚型一致。
