Abstract
Abstract: :
Purpose:Recently we have examined ET receptors, ETA and ETB, with regard to aqueous humor dynamics in the normal eye and potential changes during glaucoma. If there is a change in the localization and expression of the ET receptors in the glaucomatous eye, the effect of ET-1 will most likely be different than that occurring in the normal eye. Comparison of the localization and expression of ETA and ETB prior to and during glaucoma is needed. To that end, we have begun to examine the presence of these receptors by immunocytochemical localization in the glaucomatous iridocorneal angle (ICA) of the dog. Methods:Sections from the ICAs of six adult dogs with primary glaucoma (2 Beagles and 4 Cocker Spaniels), and four normal age-matched dogs, which had been fixed in 4% paraformaldehyde and embedded in LR White, were incubated with the primary antibody to ETA receptor (rabbit anti-rat ETA) and the secondary antibody (goat anti-rabbit immunoglobulin), conjugated with colloidal gold (10 nm). Results:The ETA receptor was present, having been observed extensively in smooth muscle cells of the ciliary body and adjacent myofibroblasts as well as among the trabecular meshwork (TM) cells. Among the TM cells in general, the degree of labeling of the A receptor appeared to be greater among the TM cells in the glaucomatous eyes than that in the normal eyes. In two instances where the ICAs were collapsed, the myofibroblasts and TM cells, which were reduced in number, were still well labeled. Conclusion:In the glaucomatous dog the presence of ETA appears to have increased when compared to the normal condition. These findings are consistent with our previous report on increased levels of endothelin in the aqueous humor of glaucomatous dogs.
Keywords: 503 outflow: trabecular meshwork • 316 animal model • 434 immunohistochemistry