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V. Kansara, A.K. Mitra; To develop and validate an in vitro model to study the permeability characteristics of cellular markers across posterior segment tissues (retina, choroid, sclera) using an Ussing's chamber. . Invest. Ophthalmol. Vis. Sci. 2004;45(13):5064.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: The purpose of this study is to develop and validate an in vitro model to study the drug permeability characteristics across posterior segment tissues (sclera, choroid, retina) using an Ussing’s chamber. Methods:Dutch Belted Pigmented rabbits weighing 2–2.5 kgs were used in these studies. Excised posterior segment tissues (retina–choroid–sclera and sclera) were mounted in an Ussing chamber. Transport studies of paracellular marker ([3H] mannitol) and transcellular marker ([14C] diazepam) was carried out across sclera and retina–choroid–sclera (RCS) tissue preparations from scleral to vitreal (S–V) and vitreal to scleral direction (V–S) for 3 hours at 37oC. The integrity of the tissue membranes during the transport studies were monitored by measuring the transepithelial electrical resistance (TEER) before and after each in vitro transport experiments. Results: There were no significance differences in either the bioelectrical parameters (transmucosal electrical resistance R) or the permeability of the sclera and RCS tissue preparations to mannitol or diazepam between the S–V directions and V–S directions. The permeability of mannitol across sclera from V–S direction and S–V direction were (4.1813 ± 1.0904 * 10–5 cm/s) and (4.1054± 1.0904* 10–5 cm/s) respectively and across RCS from S–V and V–S direction were (1.7664 ± 0.30964* 10–5 cm/s) and (1.5987 ± 0.1859* 10–5 cm/s) respectively. No significance difference was observed in the permeability of diazepam from V–S direction (4.1813 ± 1.0904 * 10–5 cm/s) and S–V direction (4.1054± 1.0904* 10–5 cm/s) across sclera and V–S direction (1.7664 ± 0.30964* 10–5 cm/s) and S–V direction (1.5987 ± 0.1859* 10–5 cm/s) across RCS. Significant difference was observed between S–V and V–S directions for permeability of diazepam across sclera and RCS. Conclusion: The results demonstrated that Ussing chamber model using posterior chamber tissues (retina, choroid and sclera) has potential as a tool for evaluating permeability characteristics of various drugs across posterior segment tissues.
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