兔眼睫状体无色素上皮细胞基底膜上的低阻抗氯离子通道

Purpose:Chloride efflux plays an important role in aqueous humor production. Chloride currents have been described in bovine non-pigmented ciliary epithelium(NPE), in transformed cultured human NPE, and in bovine volume-activated chloride channels described in the latter. It is the basolateral membranes of the NPE of ocular ciliary processes that comprise the exit pathway for the process of aqueous secretion performed by the double syncytial layer of ciliary epithelium, however. Therefore, we studied both cell-attached, and, excised,inside-out patches from basolateral membranes of the NPE. Methods:Cell-attached and cell-free excised patches were formed from the basolateral membranes of NPE and single channel currents recorded with a Dagan 3900A patch clamp amplifier. Results: A low conductance channel of 14 pS was observed and recorded in 30% of cell attached patches and in 35% of excised inside out patches under symmetrical conditions (160 mM chloride). This channel displayed a nearly linear current-voltage relationship, with an open probability that was not voltage-dependent. The channel was chloride-selective: N-methyl-D-glucamine(NMDG) used as cation did not alter the current profile nor the reversal protein. Further, with inside-out patches, the reversal potential was close to zero (0.3+/-0.5 mV(10) in symmetrical(160 mV) chloride, but shifted to -32.3+/-0.5 mV(5) when the concentration of chloride in the bathing solution was reduced to 40 mM while the recording pipette was held at 160 mM. This value approaches the theoretical equilibrium potential of chloride for these conditions. The channel anion permeability sequence was:I-＞NO3-＞ or = Br-＞Cl-＞gluconate-approximately equal to aspartate-. Three different chloride-channel blockers inhibited the channel activity. Conclusion: A low conductance channel,selective for chloride,and,modulated by beta adrenergic and VIP stimulation, based on it sensitivity to exogenously added cAMP, ATP and the catalytic subunit of PKA,is present in the exit basolateral membranes of rabbit NPE and contributes to the process of aqueous humor formation.

AIM: To investigate the relationship between cytokine level and nitric oxide (NO) content in aqueous humor after intraocular lens implantation. METHODS: All New Zealand rabbits were divided randomly into three groups: (1) control group, (2) extracapsular cataract extraction group (ECCE), (3) extracapsular cataract extraction and posterior chamber intraocular lens implantation group (ECCE+IOL). The inflammation of all experimental rabbit eyes, including cornea edema and anterior chamber exudation were observed via zoom-photo slitlamp microscope 1,3,7,14,30 d postoperation. Meanwhile, aqueous humor was drawn for white blood cell (WBC) counting and classifying, and for NO-2／NO-3 and cytokine assay, including interleukin-2(IL-2), tumour necrosis factor-α(TNF-α). Statistics were taken by SPSS softwear. RESULTS: (1) Total WBC in aqueous humor were higher and anterior chamber exudation were more severe in ECCE+IOL group than that in ECCE group and control group. (2) The level of IL-2 and TNF-α and the content of NO-2／NO-3 in aqueous humor of ECCE+IOL group were higher than that in ECCE group and control group 1-14 d postoperation respectively, and it increased to peak value at 3-7 d postoperation and decreased gradually after two weeks postoperation. (3) The change regularity of IL-2, TNF-α and NO-2／NO-3 in each group were basically similar, i.e. when the level of cytokine (IL-2 and TNF-α) was normal, the content of NO-2／NO-3 was normal too, when the level of cytokine (IL-2 and TNF-α) increased, the content of NO-2／NO-3 increased too. CONCLUSION: The intraocular inflammation after ECCE+IOL was more severe than that after simple ECCE. NO, IL-2 and TNF-α play an important role in intraocular inflammation after intraocular lens implantation. The changes of IL-2 and TNF-α level was closely related with NO content in aqueous humor.

Purpose:To study the characteristics of PEDF in cataractous aqueous humor and its expression in human lens epithelium.Methods:The PEDF concentration in the aqueous humor was measured by enzyme linked immunosorbent assay in senile (130cases) and congenital (18cases) cataract patients who underwent cataract phacoemulsification extraction surgery. Anterior lens capsular specimens were obtained from these patients to count lens epithelial cells(LEC) density. The Lens Opacities Classification System Ⅲ was used to classify the senile cataracts as cortical, nuclear, posterior subcapsular and mixed types of opacity, and quantitative analysis of the nuclear opacities was performed by Pentacam Scheimpflug imaging system. Anterior lens capsular specimens from another senile(10cases) and congenital (10cases) cataract were collected for immunofluorescence with polyclonal antibodies specific to human pigment epithelium-derived factor(PEDF).Results:The mean aqueous level of PEDF was(178. 9±87. 5)ng/ml, and there was negative linear correlation of PEDF level and age (r=0. 811, P ＜ 0. 001) . In senile cases, the aqueous PEDF concentration decreased with increasing nuclear opacities(r=0. 447, P ＜ 0.01 ), and the mean PEDF level in nuclear cataract was significantly lower than that in posterior subcapsular opacity (P ＜ 0.01 ) . PEDF immunostaining was detected in LEC of all capsular specimens.Conclusion :The PEDF level in human aqueous humor is related to age, types of cataracts and lens opacity. PEDF also express in human LEC. The study results suggest PEDF may regulate and/or protect LEC by paracrine and autocrine, and lack of PEDF may play a role in cataractogenesis.