Tyrosine kinase inhibitors suppress prostaglandin F2α-induced phosphoinositide hydrolysis, Ca elevation and contraction in iris sphincter smooth muscle

We investigated the effects of the protein tyrosine kinase inhibitors, genistein, tyrphostin 47, and herbimycin on prostaglandin F_2α- and carbachol-induced inositol-1,4,5-trisphosphate (IP₃) production, [Ca²⁺]_i mobilization and contraction in cat iris sphincter smooth muscle. Prostaglandin F_2α and carbachol induced contraction in a concentration-dependent manner with EC₅₀ values of 0.92×10⁻⁹ and 1.75×10⁻⁸ M, respectively. The protein tyrosine kinase inhibitors blocked the stimulatory effects of prostaglandin F_2α, but not those evoked by carbachol, on IP₃ accumulation, [Ca²⁺]_i mobilization and contraction, suggesting involvement of protein tyrosine kinase activity in the physiological actions of the prostaglandin. Daidzein and tyrphostin A, inactive negative control compounds for genistein and tyrphostin 47, respectively, were without effect. Latanoprost, a prostaglandin F_2α analog used as an antiglaucoma drug, induced contraction and this effect was blocked by genistein. Genistein (10 μM) markedly reduced (by 67%) prostaglandin F_2α-stimulated increase in [Ca²⁺]_i but had little effect on that of carbachol in cat iris sphincter smooth muscle cells. Vanadate, a potent inhibitor of protein tyrosine phosphatase, induced a slow gradual muscle contraction in a concentration-dependent manner with an EC₅₀ of 82 μM and increased IP₃ generation in a concentration-dependent manner with an EC₅₀ of 90 μM. The effects of vanadate were abolished by genistein (10 μM). Wortmannin, a myosin light chain kinase inhibitor, reduced prostaglandin F_2α- and carbachol-induced contraction, suggesting that the involvement of protein tyrosine kinase activity may lie upstream of the increases in [Ca²⁺]_i evoked by prostaglandin F_2α. Further studies aimed at elucidating the role of protein tyrosine kinase activity in the coupling mechanism between prostaglandin F_2α receptor activation and increases in intracellular Ca²⁺ mobilization and identifying the tyrosine-phosphorylated substrates will provide important information about the role of protein tyrosine kinase in the mechanism of smooth muscle contraction, as well as about the mechanism of the intraocular pressure lowering effect of the prostaglandin in glaucoma patients.     

The different contributions of prostaglandins (E1, E2, F2alpha,D2) to the tone and neurogenic response of bovine iris sphincter muscle

The function and sites of action of prostaglandins (PGs) vary in different animal species and tissues. In this study the influence of PGs (E₁, E₂, F_2alpha, D₂) on muscle tone and nerve-mediated contraction was investigated in isolated bovine iris sphincter muscles.None of these PGs exogenously applied influenced the neuromuscular transmission. By contrast, after treatment with indomethacin, all PGs tested contracted the muscle much more than in the absence of indomethacin and under these conditions the PGs potentiated responses to cholinergic nerve stimulation. Their ED₅₀ were (2.2 ± 0.2) × ^–7 M for PGE₁, (6.7 ± 0.3) × ^–8M for PGE₂, and (7.3 ± 0.4) × ^–8 M for PGF_2alpha. PGE₁ acted both on nerves and the muscle cell. PGE₂ had its influence mostly via nerves. Whereas PGF_2alpha was less potent in the absence of indomethacin, PGF_2alpha had much more potent action primarily on nerves and partly on muscles after treatment with indomethacin. High concentrations of PGD₂ had both pre- and post-junctional action with accompanying weak contraction of the muscle. Thus the degrees of pre- and post-junctional involvement were different from one another.There is a possibility that the application of these PGs alone masked the role of such endogenous agents. In order to understand and clarify the site and action of PGs, pretreatment with indomethacin may be useful in the iris muscle. In conclusion, PGs modulate cholinergic activity in the bovine iris sphincter muscles, as well as regulate the muscle tone.     

激光治疗上皮植入性虹膜囊肿25例临床分析

25例上皮植入性虹膜囊肿,分别用红宝石激光和YAG 激光治疗后获得较好效果。一次治疗囊肿消失21例,4例治疗后复发,其中2例经再次治疗痊愈,成功率达92.0％,有2例因角膜有混浊,而且在治疗中病人不能配合,故改用手术切除。     

中药山宝皮宁治疗单纯疱疹临床及实验研究

目的 :实验研究中药山宝皮宁对单纯疱疹病毒Ⅰ型 (HSV Ⅰ )的抑制活性并观察山宝皮宁治疗单纯疱疹的临床疗效。方法 :12 5例单纯疱疹患者随机分为治疗组、对照组 ,分别用病毒唑肌注加山宝皮宁外搽和病毒唑肌注加阿昔洛韦乳膏外搽 ,治疗 7d。实验室中Hep 2细胞体外培养检测山宝皮宁及山宝皮宁生药 (重楼 )对HSV Ⅰ的抑制活性。结果 :临床治疗中治疗组和对照组均有较好疗效 ,治疗组总有效率高于对照组 ,但统计学处理 ,差异无显著性 (P >0 0 5 ) ,而治疗组起效时间明显高于对照组 ,差异有显著性 (P <0 0 5 )。实验研究显示 ,山宝皮宁浓度在 5～ 10g/L对HSV Ⅰ病毒有直接抑制作用 ,重楼浓度在 1 2 5～ 5g/L对HSV Ⅰ病毒有直接抑制作用 ,且抗病毒作用与药物浓度呈正相关。结论 :山宝皮宁对HSV Ⅰ在体外有直接抑制作用 ,对单纯疱疹具有较好临床疗效 ,副作用小 ,安全性高 ,应用前景广阔 ,值得推广应用     

Cultivation and Ultrastructural Investigation of Human Iris Pigment Epithelial Cells

Purpose; To study the human iris pigment epithelial cells cultivation in vitro. Methods: The iris pigment epithelial cells were isolated by scraping directly or by enzyme digestion and cultured in vitro. The cells were observed under the transmission electron microscope and analized by means of immunohistochemical assay.Results: The cells obtained by scraping were easier to grow and to be passaged than those obtained by enzyme digestion. The primary cells appeared multigonal and arranged in mono-layer. Abundant pigment granules were in the cytoplasm and diminished in succeeding generations . The maculae occludentes and desmosomes and microvilli which were characteristics of epithelial cells could be found under the electronmicroscope. The immunohistochemical assay showed positive reaction of keratin antigen in cultured cells.Conclusion: The human iris pigment epithelial cells could be cultured in vitro and the cells in primary generation some characteristics be preserved. Eye Science 1997; 13: 137 - 140     

陈旧性虹膜炎的组织学观察

陈旧性虹膜炎４例４眼的组织学观察中看到炎症使多数色素细胞界限消失，色素颗粒等胞浆内容物弥散在间质中。色素细胞核体积缩小，染色质致密，电子密度增高。色素上皮细胞浆中色素颗粒明显稀少。各层组织的细胞中线粒体等细胞器少见。一份标本中微血管内皮多处操作，血小板附壁，多形核白细胞嵌于内皮细胞之间及内皮细胞层与基底模之间。     

Autoradiographic identification of muscarinic receptors in human iris smooth muscle

We have used the specific, irreversible muscarinic ligand [³H]-propylbenzilylcholine mustard to localize putative muscarinic cholinergic receptors in the smooth muscle tissue of the human iris. Analysis of autoradiograms from labeled irides reveals high grain densities over the iris sphincter muscle, consistent with the well-known pharmacology of this muscle. In addition, a smaller but significant population of muscarinic binding sites was seen in the iris dilator muscle as well. Grain densities in both muscles are substantially reduced in control tissue treated with relatively high concentrations of the muscarinic antagonists quinuclidinyl benzilate (QNB) and atropine. This is, to our knowledge, the first report of autoradiographic localization of putative muscarinic receptors in the human iris.     

Response of bovine intra-ocular muscles to transmural stimulation in the presence of various prostaglandins

Effects of prostaglandins (PGs) E1, E2 and F2 alpha on the electrically stimulated and non-stimulated smooth muscles of bovine intra-ocular tissues were investigated in vitro. PGs E1, E2 and F2 alpha contracted the sphincter and these contractions were not antagonized by either cholinergic or adrenergic blocking agents. PGF2 alpha was much weaker than PGE1 or PGE2. PGs in high concentrations produced an irreversible contracture of the sphincter muscle. In contrast, the dilator muscle contracted with PGF2 alpha, but not PGE1 or PGE2. The ciliary muscle did not respond to these PGs or to indomethacin. Electrical field stimulation with short pulses produced excitation of the intrinsic nerves. The responses produced were not altered in amplitude by the application of any dose of PGs or indomethacin, although indomethacin did lower the tone of the sphincter. PGs did not influence the amplitude of the acetylcholine-induced responses of the intra-ocular muscles. These results indicate that in each of the bovine intra-ocular muscles, PGs play a minor role in neuromuscular transmission both prejunctionally and postjunctionally. Thus, PG-induced contractions of the bovine intra-ocular muscles are considered to occur by a direct action on the muscle rather than on the nerves.     

Autoradiographic demonstration of the central origin of regenerating fibers into iris tissue implants in the rat mesencephalon

One model useful for demonstrating axonal regeneration in the central nervous system is that in which peripheral tissue, particularly the iris, is implanted into the brain or spinal cord. The aim of the present study was to establish the origin of some of the regenerating fibers by the use of an autoradiographic tracing technique. Briefly, iris implants were inserted in the caudal mesencephalon in the region of the dorsal tegmental bundle in unilaterally sympathectomized rats. Approximately two weeks later, subjects were injected with [³H]leucine in the region of the ipsilateral locus coeruleus and sacrificed two days later. Numerous labeled fibers were observed within the implants and traversing between brain and implant. Fibers formed loose plexuses, coursed along smooth muscle and grew toward blood vessels within the implants. These results may be added to fluorescent histochemical, biochemical and ultrastructural evidence supporting the regenerative capacity of central noradrenergic fibers.