Horio B, Sears M, Mead A, Matsui H, Bausher L
Department of Ophthalmology and Visual Science, Yale University School of Medicine, New Haven CT 06520-8061, USA.
Invest Ophthalmol Vis Sci. 1996 Mar;37(4):607-12.
To determine whether the intact isolated ciliary epithelial bilayer retains the alpha-2 and beta adrenergic receptor activation and interaction described for whole ciliary processes and whether this pure epithelial bilayer displays bioelectric parameters sensitive to alterations in cyclic adenosine Monophosphate (cAMP) production induced by adrenergic compounds.
The intact ciliary epithelial bilayer of the rabbit eye isolated by perfusion was mounted in a specially constructed Ussing-type chamber. The transepithelial potential difference and short-circuit current were monitored for effects induced by agents that stimulated or blocked (some did both) caMP production. Using a radioimmunoassay, the latter were studied in the pure epithelial bilayers and in whole ciliary processes.
A reproducible increase in cAMP production and an increase in the short-circuit current induced in the bilayer by isoproterenol, a nonspecific beta adrenergic agonist, were both blocked by pretreatment with either timolol, a nonspecific beta adrenergic blocking agent, or with para-aminoclonidine, an alpha-2 agonist. Maximal stimulation of cAMP with forskolin in this pure isolated epithelial preparation yields a response that is 60% of the value found in whole processes, indicating that the latter tissue contains responsive sites that are nonepithelial, probably vascular, or perhaps stromal. The degree of inhibition of the beta adrenergic receptor by alpha-2 agonists was not very different in the two preparations. On the other hand, inhibition of the epithelial vasointestinal peptide receptor by neuropeptide Y or alpha-2 agonism was considerably heightened in the pure bilayered epithelial preparation.
The isolated intact ciliary epithelial bilayer, when stimulated with beta adrenergic receptor agonists, vasointestinal peptide, or forskolin, produces increased cAMP and its transepithelial potential becomes hyperpolarized. These chemical and bioelectrical effects are prevented by pretreatment with either alpha-2 adrenergic agonists or beta adrenergic blocking agents. The results obtained in the isolated intact purely epithelial ciliary bilayer confirm that the ciliary epithelium is the source of adrenergic receptor activation and interaction and support the hypothesis that aqueous humor production is regulated by interactions between epithelial alpha-2 and beta adrenergic receptors.
确定完整的孤立睫状上皮双层是否保留了在整个睫状体中所描述的α₂和β肾上腺素能受体激活及相互作用，以及这种纯上皮双层是否表现出对肾上腺素能化合物诱导的环磷酸腺苷（cAMP）产生变化敏感的生物电参数。
通过灌注分离的兔眼完整睫状上皮双层被安装在特制的尤斯灌流室中。监测跨上皮电位差和短路电流，以观察刺激或阻断（有些兼具二者作用）cAMP产生的药物所诱导的效应。使用放射免疫测定法，在纯上皮双层和整个睫状体中研究后者。
非特异性β肾上腺素能激动剂异丙肾上腺素在双层中诱导的cAMP产生的可重复性增加和短路电流增加，均被非特异性β肾上腺素能阻断剂噻吗洛尔或α₂激动剂对氨基可乐定预处理所阻断。在这种纯分离的上皮制剂中，用毛喉素对cAMP进行最大刺激产生的反应是在整个睫状体中发现值的60%，表明后者组织含有非上皮性的反应位点，可能是血管性的，或者也许是基质性的。在两种制剂中，α₂激动剂对β肾上腺素能受体的抑制程度没有很大差异。另一方面，在纯双层上皮制剂中，神经肽Y或α₂激动作用对上皮血管活性肠肽受体的抑制作用显著增强。
当用β肾上腺素能受体激动剂、血管活性肠肽或毛喉素刺激时，分离的完整睫状上皮双层会产生cAMP增加，其跨上皮电位变得超极化。这些化学和生物电效应可通过用α₂肾上腺素能激动剂或β肾上腺素能阻断剂预处理来预防。在分离的完整纯上皮睫状双层中获得的结果证实，睫状上皮是肾上腺素能受体激活和相互作用的来源，并支持房水生成受上皮α₂和β肾上腺素能受体之间相互作用调节的假说。
