Regional differences in functional receptor distribution and calcium mobilization in the intact human lens.
Regional differences in functional receptor distribution and calcium mobilization in the intact human lens.
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发表时间：
2001-09
影响因子：
4.4
通讯作者：
D. Collison;G. Duncan
中科院分区：
文献类型：
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作者：
D. Collison;G. Duncan
目的 研究酪氨酸激酶和 G 蛋白偶联受体激动剂在完整人晶状体中产生的 Ca(2+) 动员动力学的区域差异，并表征不同区域中参与 Ca(2+) 信号传导的主要受体亚型。方法 将整个人晶状体前侧朝下放置在塑料室中，并在 30°C 下灌注人工房水 (AAH)。掺入 fura-2 后，使用落射荧光技术监测完整晶状体赤道或中央前上皮细胞中的胞质 Ca(2+) 水平。将溶解在 AAH 中的激动剂以连续的短脉冲施加到晶状体上。结果 中央前晶状体上皮细胞对 10 µM 乙酰胆碱 (ACh) 和组胺产生强烈反应；对三磷酸腺苷 (ATP) 只有很小的反应；对 10 microM 肾上腺素、10 ng/ml 上皮生长因子 (EGF) 或 TGF α 或 50 ng/ml 血小板衍生生长因子 (PDGF)-AB 没有反应。相反，赤道细胞对10μM ATP和组胺、10ng/ml EGF（或TGFα）和50ng/ml PDGF-AB产生强烈反应，但对10μM ACh或10μM肾上腺素没有反应。 EGF 诱导的赤道细胞反应被酪氨酸磷酸酶 (AG1478) 完全阻断，酪氨酸磷酸酶是 EGF 受体酪氨酸激酶的特异性抑制剂。卡巴胆碱（ACh 的不可水解类似物）和毛果芸香碱（M1 毒蕈碱受体特异性激动剂）均在晶状体的每个区域中产生相同的由 ACh 引起的响应幅度趋势。嘌呤能激动剂诱导的赤道Ca(2+)动员的效力顺序与P2Y(2)受体亚型一致。组胺诱导的反应被 10 µM 曲普立啶（一种特异性 H(1) 受体拮抗剂）消除，但不受特异性 H(2) 和 H(3) 拮抗剂雷尼替丁和硫哌丁胺的影响。结论。整个晶状体不同区域的功能受体活性存在空间异质性。 EGF 和 PDGF 的重要生长因子受体仅在成熟人类晶状体的赤道细胞中具有功能活性。这项研究进一步表明，ACh、组胺和 ATP 诱导的反应分别由 M1 毒蕈碱受体、H(1) 组胺和 P2Y(2) 嘌呤能受体的激活引起。
PURPOSE To investigate regional differences in Ca(2+) mobilization kinetics in the intact human lens produced by exposure to agonists of tyrosine-kinase and G-protein-coupled receptors and to characterize the major receptor subtypes involved in Ca(2+) signaling in the different regions. METHODS Whole human lenses were placed anterior side down in a plastic chamber and perifused with artificial aqueous humor (AAH) at 30 degrees C. After fura-2 incorporation, cytosolic Ca(2+) levels were monitored by using epifluorescence techniques in either the equatorial or central anterior epithelial cells of the intact lens. Agonists dissolved in AAH were applied to the lens in successive short pulses. RESULTS Central anterior lens epithelial cells produced a large response to 10 microM acetylcholine (ACh) and histamine; only a small response to adenosine triphosphate (ATP); and no response to 10 microM adrenalin, 10 ng/ml epithelial growth factor (EGF) or TGF alpha, or 50 ng/ml platelet-derived growth factor (PDGF)-AB. Conversely, the equatorial cells produced a strong response to 10 microM ATP and histamine, 10 ng/ml EGF (or TGF alpha), and 50 ng/ml PDGF-AB, but failed to respond to 10 microM ACh or 10 microM adrenalin. The EGF-induced response in the equatorial cells was blocked completely by tyrphostin (AG1478), a specific inhibitor of the EGF receptor tyrosine kinase. Carbachol, a nonhydrolyzable analogue of ACh, and pilocarpine, the M1 muscarinic receptor-specific agonist, both produced the same trend of response amplitude elicited by ACh in each region of the lens. The potency order of purinergic agonist-induced Ca(2+) mobilization at the equator was consistent with the P2Y(2) receptor subtype. The histamine-induced response was abolished by 10 microM triprolidine, a specific H(1) receptor antagonist, but remained unaffected by the specific H(2) and H(3) antagonists, ranitidine and thioperamide, respectively. CONCLUSIONS. There is a spatial heterogeneity in functional receptor activity in different regions of the whole lens. The important growth factor receptors for EGF and PDGF are functionally active only in the equatorial cells of the mature human lens. This study further shows that the ACh, histamine, and ATP-induced responses arise from the activation of M1 muscarinic, H(1) histamine, and P2Y(2) purinergic receptors, respectively.