Rabbit Aqueous Humor Research Articles

Effect of corticoids on protein concentration in rabbit aqueous humor after argon laser surgery of the iris (author's transl)

A high dose of corticoid premedication was applicated intramuscularly five hours before laser surgery. Following laser coagulation of the pigmented iris the protein concentration in the aqueous humor was measured every hour. The initial increase in protein concentration was found to be lower than in earlier experiments without premedication. In contrast to earlier results without corticoid premedication, the reaction of the untreated contralateral eye was suppressed.

The protective effect of Na-hyaluronate to corneal endothelium

The very viscous solution of a special fraction of Na-hyaluronate, Healon ® was used to replace the aqueous humor in rabbits. The intraocular pressure, corneal thickness and endothelial cell count after Na-hyaluronate injection were not significantly different than after replacing the aqueous humor with balanced salt solution. The same viscous Na-hyaluronate solution was also shown to protect the corneal endothelium from mechanical damage caused by contact with methacrylate surfaces. Corneal endothelial cell counts in histological preparations and in scanning electron micrographs clearly showed that placing the viscous Na-hyaluronate solution between the methacrylate surface and the corneal endothelium prevented the mechanical damage.

Aqueous humour and ultraviolet radiation.

Studies on the ultraviolet ray absorption in the aqueous humour of rabbit, cat, monkey, guinea pig, and rat showed marked species differences. In the rabbit aqueous the ascorbic acid, the proteins, and some amino acids (tyrosine, phenylalanine, cystine, and tryptophane) are together responsible for the total absorption, and a very great part of it refers to the ascorbic acid content. Accordingly, species with significant amounts of ascorbic acid in the aqueous (monkey, rabbit, guinea pig) have a greater absorption capacity towards ultraviolet radiation than species (cat, rat) lacking this substance. This effect of the ascorbic acid may contribute in protecting the lens against the most biotoxic ultraviolet rays. It seems that the ascorbic acid concentration is highest in the aqueous of typical day animals and lowest in species being active in the dark, indicating a correlation between the aqueous' ascorbic acid level and the quantity of incident light on the eye. The possible significance of changed aqueous ultraviolet ray absorption in the pathogenesis of human cataract development is discussed.

Concentration of Glutamic Acid, Glycine and Cysteine in the Aqueous Humor of Rabbits after Topical and Peroral Application

A pilot study was performed in order to elucidate whether by local or peroral application of glutamic acid, glycine, and cysteine the amino acid concentrations in the aqueous humor could be increased.

Preparation, gas chromatography and mass spectrometry of methyl and trimethylsilyl esters of indomethacin

The preparation and gas chromatographic-mass spectrometric behavior of the methyl and trimethylsilyl esters of indomethacin, 1-( p-chlorobenzoyl)-5-methoxy-2-methylindole-3-acetic acid, are described. Reaction of this anti-inflammatory drug with diazomethane or bis(trimethylsilyl)acetamide forms the expected esters. Derivatization with dimethylformamide dimethylacetal yields two compounds, the methyl ester (major product) and a methyl ester-dimethylaminomethylene condensation (at the α-carbon of the side chain) product (minor). Experiments with 5-O-desmethyl-indomethacin have demonstrated that using the described diazomethane methylation conditions no alkylation of the phenolic group occurs. Esterification combined with an isolation procedure allows the determination of indomethacin levels in plasma and aqueous humor of rabbits, the 4-fluorobenzoyl analog serving as internal standard. The derivatives exhibit excellent electron capture properties allowing quantitative assay of the drug at the submicrogram level. Precision and accuracy for plasma samples varied from 92 ± 19% (5 ng/ml) to 96 ± 1.5% (1000 ng/ml). The analogous values for aqueous humor are superior: 97 ± 5.6% and 99 ± 2.2%, respectively.

Aldosterone: Its occurrence, metabolism and binding in the rabbit eye

Aldosterone levels in rabbit aqueous humour and blood plasma were determined by radioimmunoassay and circulating aldosterone was identified radiochemically. The concentration of aldosterone was 22·9±14·2 pg/ml in aqueous and 87·1±26·6 pg/ml in plasma. There was no detectable transformation of aldosterone in the aqueous and very little in the cornea in vitro. In the ciliary body+iris aldosterone was transformed to several metabolites of which only tetrahydroaldosterone could be characterized and this only in small amounts. A small but definitive specific aldosterone binding in the ciliary body+iris was established. The apparent association constant ( K as) was about 10 13 mg of tissue/mol and the concentration of binding sites varied from 0·22 to 0·58 fmol/mg of wet tissue. The binding could be displaced by spirolactone but not by dexamethasone.

Corneal Penetration of Rifampin

We tested the corneal penetration of rifampin in four vehicles: dimethylsulfoxide, polyethylene glycol, an ocular lubricant, and as rifampin ointment. We measured drug concentrations in the aqueous humor in rabbits after topical instillation of 1 and 2.5% rifampin according to two dosage schedules. Drug concentrations in the aqueous humor were bactericidal to Mycobacterium leprae. Since leprosy of the cornea, iris, and ciliary body may develop despite standard systemic bacteriostatic treatment, treatment of leprotic involvement of the anterior eye may be enhanced by intensive topical application of rifampin.

Entry of Insulin into Aqueous Humor of Rabbits After Feeding

In order to evaluate more clearly the possible physiological effects of insulin on the lens, insulin was measured in the aqueous humor and plasma of rabbits in the fasting state and at hourly intervals after refeeding. The mean insulin concentration in plasma rose from 1,200 to a peak of 3,000 pg/ml at 1 h, while in aqueous humor it rose from 28 to a peak of 48 pg/ml at 3 h (1 pg = 0.025 µU). The results suggest that the blood-aqueous barrier is relatively impermeable to insulin. Glucose concentrations in aqueous humor and plasma were correlated with the insulin concentrations. Possible insulin-mediated metabolic consequences of uveitis and diabetes to the lens are discussed.

Lysophosphatidyl choline and cataracts in uveitis.

In aqueous humor from rabbits with uveitis or after anterior chamber paracentesis, the levels of lysophosphatidyl choline (LPC) were 10.2mug/ml and 14.7mug/ml, respectively. These LPC levels induce early cataractous changes in the rabbit lens in culture. Analysis of the fatty acid composition of LPC showed that saturated fatty acids were more predominant in secondary aqueous humor than in primary aqueous humor. In vitro, natural LPC induced more pronounced gains in sodium ions and water by the lens than similar concentrations of synthetic L-alpha-lysopalmitoyl phosphatidyl choline. In contrast to prostaglandin E, the levels of LPC in aqueous humor of rabbits with uveitis are cataractogenic. Thus, LPC or its precursors, rather than prostaglandins, are involved in the production of cataracts in uveitis.

The Effects of Dipivalyl Epinephrine on the Eye

We treated one eye each of ten patients with ocular hypertension with dipivalyl epinephrine (DPE), a congener of epinephrine. Pupil size and intraocular pressure were measured before and at intervals up to 240 minutes after instillation of a single drop of DPE in concentrations from 0.005 to 0.5%. Concentrations of 0.025% DPE and greater significantly reduced IOP, and mydriasis was induced by concentrations of 0.1% DPE or greater. Comcentrations of 0.1% DPE, instilled twice daily for one month, significantly reduced intraocular pressure during diurnal testing on days 2 and 31. No toxic side effects were noted. The DPE produced dose-related increases of cyclic adenosine monophosphate in the aqueous humor of rabbits.

Phospholipid distributions and fatty acid composition of lysophosphatidylcholine and phosphatidylcholine in rabbit aqueous humor, lens and vitreous

The phospholipid distributions in rabbit lens and vitreous humor are remarkably similar to those of rabbit erythrocytes with a predominance of phosphatidylethanolamine (PE) and phosphatidylcholine (PC) and lesser levels of sphingomyelin. A blood-aqueous and blood-vitreous barrier exists for phospholipids. In aqueous humor and vitreous humor, phospholipid concentrations were 1 2 to 1 30 those in serum. Only PE occurs in higher levels in vitreous than in serum, probably reflecting direct diffusion from the retina. Levels of lysophosphatidylcholine (LPC) in rabbit aqueous humor average 4·3 μg/ml. No LPC was present in rabbit lens. The fatty acid composition of PC and LPC was determined in lens, intraocular fluids, and serum. PC from rabbit ocular fluids or lens contains a higher proportion of saturated fatty acids than rabbit serum, and the long chain saturated fatty acids (>22:0) are found only in the ocular fluids.

Effect of Stimulation of the Oculomotor Nucleus on Intraocular Pressure, Outflow Facility and Protein Concentration of the Aqueous Humour in Rabbits

The effect of electrical stimulation of the oculomotor nucleus on intraocular pressure, outflow facility and protein concentration of the aqueous humour was studied in uncurarized rabbits. Stimulation caused an increase in the equilibrium pressure of both eyes, due to the increased tension of the extraocular muscles. The outflow facility of the aqueous humour was increased by about 50% in the eye with miosis as compared with the other eye. The protein concentration of the aqueous humour was slightly elevated in the experimental eye as compared with the control eye

Lens as the Chief Source of Fructose in Rabbit Aqueous Humor

Three months after the left eyes of seven rabbits had been rendered aphakic, samples of aqueous humor from the anterior chamber of both eyes and blood samples from the ear vein were removed and analysed for fructose, glucose and lactic acid. The average fructose level was 5.4 mg/l00 ml aqueous humor in the normal eyes as compared to a level of 1.4 mg/l00 ml in the aphakic eyes. The blood fructose level was 1.7 mg/l00 ml plasma, which is not significantly different from the level found in aphakic aqueous humor. The glucose levels in the aqueous humor were not affected by lens removal. In aphakic eyes, the aqueous humor lactic acid level was 60% of the normal. From these data, it is clear that the lens is the only ocular tissue that supplies fructose to the aqueous humor. It has also been confirmed that the lens supplies to the aqueous humor only a part of the lactic acid not derived from the blood.

Pyruvate and citrate concentrations in rabbit aqueous humour determined by an enzymatic procedure.

A modification of Moellering & Gruber's enzymatic‐spectrophotometric method (1966) has been employed for determining the pyruvate and citrate concentrations in rabbit aqueous humour. Aqueous humour samples from non‐fasting, female albino rabbits of Danish country breed, aged from 4 to 36 months, were found to have the following concentrations (mean ± s.d.):pyruvate (28 animals): 339 μmol/1 ± 50citrate (28 animals): 354 μtmol/1 ± 48glucose (9 animals): 6.1 mmol/1 ± 0.6, determined with a Beckmann glucose analyzer.The following concentration ratios were found in rabbit aqueous humour:pyruvate/citrate: 0.98 ± 0.18, glucose/pyruvate: 19.2 ± 2.2, and glucose/citrate: 17.3 ± 2.5.The pyruvate/citrate ratio was found to decrease with increasing age (0.05 > P > 0.02).Citrate and pyruvate determinations in the same watery pool yielded a day‐to‐day accuracy of the method expressed by coefficients of variation of 7.6% for pyruvate and 6.1% for citrate.

Carbonic anhydrase in the developing ciliary processes of the rabbit eye

Carbonic anhydrase activity in the developing ciliary processes of rabbit eyes has been investigated by a histochemical method. The non-pigmented epithelium of the ciliary processes of the foetus shows no enzyme activity although this is present in other ocular tissues. Soon after birth, carbonic anhydrase appears in the non-pigmented epithelium and reaches the adult level in about 4 weeks. It is suggested that this appearance of carbonic anhydrase coincides with the onset of the formation of aqueous humour in rabbits, and that aqueous formation is dependent on carbonic anhydrase in this species.

Diurnal variation in the intraocular pressure and outflow resistance of the aqueous humour in rabbits

Abstract The diurnal variations in the intraocular pressure and outflow resistance of the aqueous humour have been studied in 43 healthy young pigmented rabbits for a period of ten days using topical anaesthesia. The determinations yielded a statistically significant phasic variation in the intraocular pressure of the order of 1 to 2 mmHg, whereas a statistically significant phasic variation in the outflow resistance could not be shown. In spite of the fact that a shorter compression with the tonometer was performed than the classical 4 min. tonography, a clear ophthalmotonic consensual reaction could be observed in the second eye. The probability density functions of the measured parameters suggested the influence of several “disturbing factors” in the course of the measurements.

The effect of sympathetic nerve stimulation on the aqueous humor dynamics of the cocaine pretreated rabbit

The effect of electrical stimulation of the cervical sympathetic nerve on the outflow facility of aqueous humor in normal and cocaine pretreated rabbits is reported. Outflow facility was determined using the pressure decay curve technique. A significant increase in outflow facility resulting from stimulation in the cocaine pretreated animals was observed; the increase could be prevented by an intravitreous injection of phentolamine. The results of this study provide further evidence for the presence of an alpha-adrenergic mechanism involved in the outflow of aqueous humor in the rabbit eye.

The routes for bulk drainage of aqueous humour in rabbits with and without cyclodialysis.

The bulk drainage of aqueous humour into the general circulation and into the orbital tissues was studied with 131I-labelled albumin and red dextran (molecular weight 40,000) in rabbits with and without cyclodilaysis. In animals at a normal intraocular pressure of about 20 mm Hg and without an artificial cleft between the anterior chamber and the suprachoroid the rate of aqueous bulk flow into the general circulation was 3.99 ± 0.55 μl/min. There seemed to be some outflow also through other routes ending up in the episcleral tissues in the limbus region but less than 0.11 ± 0.02 μl/min was drained in that way. Even in dead eyes maintained at an intraocular pressure of 14 mm Hg only negligible quantities of labelled anterior chamber fluid passed into the tissues with bulk flow. In acute experiments in living animals, after a cleft had been opened between the anterior chamber and the suprachoroid without damaging the sclera, the rate of aqueous production was 5.64 ± 0.65 μl/min. On an average 54% of the aqueous humour was drained into the suprachoroid from where great amounts penetrated the sclera in part by way of perivascular spaces in part directly through the scleral substance. Before the cleft was produced the facility of outflow was 0.237 ± 0.038 μl/min per mm Hg, afterwards it was on an average 0.505 ± 0.092 μl/min per mm Hg higher.

The drainage of blood from the uvea and the elimination of aqueous humour in rabbits

The drainage of uveal blood and aqueous humour via vortex veins, as compared with that through anterior routes, was studied in rabbits. The flow, including blood and aqueous humour, from the vessels in the limbal region was compared with the flow from an opened vortex vein. The results indicate that less than 1% of the total uveal blood drainage is through the anterior ciliary veins. 131I-labelled human serum albumin was introduced into the anterior chamber, and the activity drained into the general circulation via the vortex veins was compared with the total activity delivered into the general circulation. The results indicate that if any of the bulk flow of aqueous humour leaves the eye through the vortex veins, it is less than 1.2% of the total bulk drainage.

Electrophoretical aspect of the primary and secondary aqueous humour in rabbits.

Acta OphthalmologicaVolume 39, Issue 5 p. 887-898 ELECTROPHORETICAL ASPECT OF THE PRIMARY AND SECONDARY AQUEOUS HUMOUR IN RABBITS Petar Sokolic, Petar Sokolic Ophthalmic Clinic and the Institute of the Pathophysiology of Hospital Rebro, Zagreb (Jugoslavija)Search for more papers by this author Petar Sokolic, Petar Sokolic Ophthalmic Clinic and the Institute of the Pathophysiology of Hospital Rebro, Zagreb (Jugoslavija)Search for more papers by this author First published: October 1961 https://doi.org/10.1111/j.1755-3768.1961.tb07753.xCitations: 1AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume39, Issue5October 1961Pages 887-898 RelatedInformation