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Abstract #6169 Published in IGR 2-2

Effect of brimonidine on rabbit trabecular meshwork hyaluronidase activity

Benozzi J; Jaliffa CO; Firpo Lacoste F; Llomovatte DW; Keller Sarmiento MI; Rosenstein RE
Investigative Ophthalmology and Visual Science 2000; 41: 2268-2272


PURPOSE: To study the presence of hyaluronidase activity in the rabbit trabecular meshwork and its regulation by brimonidine. METHODS: A spectrophotometric assay that consists of the assessment of N-acetylhexosamine groups released from hyaluronic acid was used to examine hyaluronidase activity. Cyclic adenosine monophosphate (cAMP) levels were assessed by radioimmunoassay. RESULTS: Hyaluronidase activity was detected in the rabbit trabecular meshwork. Its optimal activity was in the acid range of pH 3.8. Brimonidine significantly increased trabecular hyaluronidase-specific activity and decreased cAMP accumulation. Yohimbine significantly inhibited the effect of brimonidine on both hyaluronidase activity and cAMP accumulation. CONCLUSIONS: The finding of endogenous hyaluronidase activity in rabbit trabecular meshwork supports the hypothesis that this tissue can metabolize its own glycosaminoglycan (GAG) products. The present results suggest, however, that the hypotensive effect of brimonidine could be mediated, at least in part, by its ability to increase GAG catabolism, probably through a cAMP-independent mechanism.

Dr. J. Benozzi, Departamento de Bioquimica Humana, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina


Classification:

11.3.3 Apraclonidine, brimonidine (Part of: 11 Medical treatment > 11.3 Adrenergic drugs)



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