摘要:

In the present study we have determined the effects of acute diamter changes in the recently discovered episcleral arteriovenous anastomoses (AVA) on episcleral venous pressure and intraocular pressure (IOP) in the rabbit eye. The pressure was measured in episcleral arterioles, AVA and veins (vascular pressure) with a pressure chamber mounted on the tip of a microendoscope.After constriction of the AVA following topical administration (100μg) of epinephrine we observed a decrease in the episcleral vascular pressure as well as in the IOP. Acute widening of the AVA after topical administration of 5mg nitroprusside led to a significant increase in the pressure of arterioles, AVA, veins and IOP which lasted several min. After 0.5mg topical nitroprusside the blood flow in the AVA increased. No significant effects were seen in the intravascular pressures; the IOP had a tendency to decrease.Experimental lowering of the IOP to 10mmHg caused an increase of vascular diameters and of blood flow in the AVA.It is assumed that–at least in drastic hemodynamic disorders–the degree of the AVA-perfusion might influence aqueous humor outflow and IOP due to changes of the episcleral venous pressure.

ISSN:0271-3683    

DOI:10.3109/02713689609017615

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

Transforming growth factor-beta (TGF-β), a multifunctional cytokine which has been identified in normal and inflamed ocular fluids, may play a role in the evolution of inflammatory ocular lesions. In this study we utilized a rabbit model of LPS-induced uveitis to determine if exogenous TGF-β2 could alter its course. Recombinant TGF-β2 (1-2000 ng), LPS (10 or 20 ng), or TGF-β2 (100 ng) plus LPS (10 ng) were injected intravitreally in one eye of a New Zealand white rabbit and the contralateral eye served as a paired control which received an equal volume of vehicle. The uveitic response was assessed by biomicroscopic examination of the anterior uvea and analysis of protein and cells in the aqueous humor. Ocular tissues were processed for histologic, immunohistochemical andin situhybridization analyses. Rabbits injected with doses of TGF-β2↣500 ng developed a mild uveitic response, compared to LPS alone, accompanied by expression of IL-1βmRNA and protein in the anterior uvea. Interestingly, rabbits coinjected with LPS (10 ng) and a nonuveitic dose (100 ng) of TGF-β2 exhibited a similar increase in ocular vascular permeability, but a decrease in inflammatory cell infiltration into the anterior uvea and aqueous humor (1185↣117 versus 2465↣176; p<0.05). No evidence of inflammation was observed in eyes injected with 100 ng TGF-β2 alone. Similar to other models of inflammation, TGF-βmay interrupt the cascade of events leading to ocular inflammation, thereby suggesting therapeutic potential.

ISSN:0271-3683    

DOI:10.3109/02713689609017616

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

Calcitonin gene-related peptide (CGRP) and Substance P (SP)-immunoreactive nerves have been found in the anterior uvea of various mammalian species. Although SP is known to play a major role in control of pupil motility in rabbits, little is known about the effect of CGRP on the iris smooth muscles. We isolated iris sphincter and dilator muscles from rabbit eyes and investigated the mechanical responses and intracellular cyclic AMP (cAMP) levels in these muscles. CGRP (up to 0.1μM) had no effect on either the resting muscle tone or the amplitude of contraction evoked by field stimulation of the sphincter. On the other hand, CGRP (0.1μM) relaxed dilator muscle which had been pre-contracted by phenylephrine and reduced the amplitude of contraction evoked by field stimulation. These responses were antagonized by CGRP (8-37), a CGRP antagonist. The phosphodiesterase inhibitor, 3-isobutyl-l-methylxanthine (IBMX), dose-dependently inhibited the contraction evoked by field stimulation. However, 3μM IBMX had no effect on CGRP inhibition of twitch contraction in this preparation. CGRP had little effect on cAMP production in dilator muscle either with or without IBMX. In conclusion, the miosis which occurs during an ocular inflammatory response, when both CGRP and SP are thought to be released from terminals of sensory neurons, results from CGRP relaxation of the dilator and from the strong contractile effect of SP on the sphincter. Adenylate cyclase activation does not seem to be involved in the relaxant effect of CGRP on the dilator.

ISSN:0271-3683    

DOI:10.3109/02713689609017617

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

This study has examined the localisation and receptor-binding of the endothelins in retina and choroid of human and rat origin. Immunoreactivity to anti-ET1 and anti-ET3 was investigated in trypsin digests, frozen sections and ultrathin sections using immunocytochemistry and immunogold labelling techniques. In addition, receptor binding of125I-ET1 and125I-ET3 was visualised and quantified using autoradiography and image analysis. Intense immunoreactivity to anti-ET1 and anti-ET3 was observed in the photoreceptor inner segments and in the outer plexiform layer (OPL) of human and rat retina. Ultrastructural localisation using immunogold labelling confirmed the presence of ET1 and ET3 in the photoreceptor cells. In retinal vascular digests, ET1 was visualised in the arteries, arterioles and at the pre-arteriolar sphincters, however, immunoreactivity to anti-ET3 was absent in the retinal vasculature. Both ETAand ETB-type receptor binding sites to125I-ET1 and125I-ET3 were detected in the vascular smooth muscle of choroidal and retinal vessels with the former being predominant. Extravascular binding sites of the ETB-type were found in the ganglion cell layer.

ISSN:0271-3683    

DOI:10.3109/02713689609017618

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

This paper describes the first successfulin vivoapplication of antisense DNA technology to induce the accumulation of photoreceptor outer segment derived debris in the retina. An antisense oligonucleotide (CatSC), which was previously demonstrated to be an effective tool to induce debris accumulationin vitro, was injected into the vitreous of pigmented and non-pigmented rats. The animals were euthanased 7 days after the injections. The number of inclusions significantly increased in the RPE layer of Long Evans and RCS-rdy + rats injected with 66 ug of CatSC to 96.13↣2.6 (SD) (p<0.0003) and 204.2↣39.3 (SD) (p<0.0001), respectively. The difference between the number of phagosome-like inclusions present in control saline, 6.6 ug of CatSC or 66 ug of sense oligonucleotide (S1) injected animals was not statistically significant. There were no abnormalities observed in the inner layers of the retina but the accumulation of phagosome-like inclusions was accompanied by disorganisation in the apices of outer segments. The large number of inclusions found in CatSC treated animals showed the characteristics of phagosomes containing stacks of undigested photoreceptor outer segment membranes which suggest that the lysosomal digestion process was halted or at least slowed down by the antisense oligonucleotide.

ISSN:0271-3683    

DOI:10.3109/02713689609017619

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

ISSN:0271-3683    

DOI:10.3109/02713689609017620

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor