Effects of chondroitin sulfate on metabolism of trabecular meshwork

Glycosaminoglycans are believed to play a role in the physiological functions of trabecular meshwork. The effects of chondroitin sulfate on the metabolism of trabecular meshwork were studied by replacing the aqueous humor in the right eye (experimental eye) of 12 albino rabbits with 0.3 ml of chondroitin-4-sulfate solution (10 mg ml-1 in glucose-supplemented phosphate buffered saline). The aqueous humor in the left eye (control eye) was replaced with the phosphate buffered saline-glucose solution in the same manner. The intracameral procedures were performed twice a week for four weeks (initial injection period), and then discontinued for another four weeks (resting period). No significant or prolonged increase in the intraocular pressure was observed during either period in any eyes. Subsequent intracameral injections performed after the resting period, however, caused an intraocular pressure elevation in 10 of the 12 experimental eyes. During this second injection period, the injections were carried out whenever the intraocular pressure of experimental eyes dropped to the control value. The pressure generally remained 5-10 mmHg above that of the control eyes for periods ranging from two days to four weeks. In the eyes with elevated intraocular pressure, light microscopy showed that the trabecular beams were compact and sclerotic and the intertrabecular spaces were narrower. Chamber angle tissues obtained from the eyes with elevated intraocular pressure incorporated more radioactive precursors into glycosaminoglycans than those from the control eyes. The synthesis of glycosaminoglycans and the metabolism of trabecular meshwork seemed to be modified by the long-term chondroitin sulfate treatment.