Efficacy and selectivity of phosphodiesterase-targeted drugs in inhibiting photoreceptor phosphodiesterase (PDE6) in retinal photoreceptors.
Efficacy and selectivity of phosphodiesterase-targeted drugs in inhibiting photoreceptor phosphodiesterase (PDE6) in retinal photoreceptors.
复制标题
磷酸二酯酶靶向药物抑制视网膜光感受器中光感受器磷酸二酯酶（PDE6）的功效和选择性。
DOI：
10.1167/iovs.05-0257
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发表时间：
2005
影响因子：
4.4
通讯作者：
Cote,RickH
中科院分区：
文献类型：
--
作者：
Zhang,Xiujun;Feng,Qing;Cote,RickH
目的。磷酸二酯酶 (PDE) 抑制剂是重要的治疗药物，但其对光感受器 PDE (PDE6) 和光感受器细胞的影响知之甚少。表征了各类 PDE 抑制剂对纯化视杆和视锥 PDE6 以及完整视杆外节 (ROS) 的效力和选择性。测定纯化的杆状和锥状 PDE6 的同工酶选择性 PDE 抑制剂的抑制常数 (K i)。 PDE 抑制剂对分离的 ROS 悬浮液中 cGMP 水平的干扰通过 cGMP 酶联免疫测定结果进行定量。大多数 PDE5 选择性抑制剂都是优秀的 PDE6 抑制剂。伐地那非是一种有效的 PDE5 抑制剂 (K i= 0.2 nM)，也是测试中最有效的 PDE6 抑制剂 (K i= 0.7 nM)。扎普司特是唯一比 PDE5 更有效地抑制 PDE6 的药物。 PDE1 选择性抑制剂在抑制 PDE6 方面同样有效。在完整的 ROS 中，PDE 抑制剂提高了 cGMP 水平，但没有一种抑制剂能够完全抑制 PDE6。它们提高 ROS 中 cGMP 水平的能力远低于抑制纯化酶的能力。 PDE5/6 选择性药物与 PDE6 活性位点的抑制性 γ 亚基之间的竞争被认为会降低药物在酶活性位点的有效性。结论。几类 PDE 抑制剂可以同等地抑制 PDE6 以及它们所针对的 PDE 家族。在完整的 ROS 中，高 PDE6 浓度、γ 亚基与活性位点的结合以及钙反馈机制会减弱 PDE 抑制剂在视觉转导过程中抑制 PDE6 和破坏 cGMP 信号通路的有效性。
purpose. Phosphodiesterase (PDE) inhibitors are important therapeutic agents, but their effects on photoreceptor PDE (PDE6) and photoreceptor cells are poorly understood. The potency and selectivity of various classes of PDE inhibitors on purified rod and cone PDE6 and on intact rod outer segments (ROS) were characterized.methods. The inhibition constant (K i) of isozyme-selective PDE inhibitors was determined for purified rod and cone PDE6. Perturbations of cGMP levels in isolated ROS suspensions by PDE inhibitors were quantitated by a cGMP enzyme-linked immunoassay.results. Most PDE5-selective inhibitors were excellent PDE6 inhibitors. Vardenafil, a potent PDE5 inhibitor (K i= 0.2 nM), was the most potent PDE6 inhibitor tested (K i= 0.7 nM). Zaprinast was the only drug that inhibited PDE6 more potently than did PDE5. PDE1-selective inhibitors were equally effective in inhibiting PDE6. In intact ROS, PDE inhibitors elevated cGMP levels, but none fully inhibited PDE6. Their potency for elevating cGMP levels in ROS was much lower than their ability to inhibit the purified enzyme. Competition between PDE5/6-selective drugs and the inhibitory γ-subunit for the active site of PDE6 is proposed to reduce the effectiveness of drugs at the enzyme-active site.conclusions. Several classes of PDE inhibitors inhibit PDE6 equally as well as the PDE family to which they are targeted. In intact ROS, high PDE6 concentrations, binding of the γ-subunit to the active site, and calcium feedback mechanisms attenuate the effectiveness of PDE inhibitors to inhibit PDE6 and disrupt the cGMP signaling pathway during visual transduction.