Effect of Ouabain on Intraocular Pressure in Rabbits

ABSTRACT

Effect of Ouabain administration on aqueous humor dynamics were studied in albino rabbits. Intravenous injection of 0.1 mg/kg of ouabain in 10 rabbits produced significant reduction of intraocular pressure. The highest lowering of intraocular pressure occurred 70 minutes after the injection, its magnitude being 35.54% of the original pressure. The intraocular pressure returned to its original pressure 117.0 minutes after the injection. Perilimbal suction cup studies revealed 26.92 % reduction in aqueous flow. Intravitreal injection of O.1 micro gram of ouabain dissolved in 0.02 ml performed in 5 rabbits' eyes produced marked lowering of intraocular pressure. The maximum tension lowering effect (60.15%) was observed 4.6 days after the administration, and the tension recovered 15.8 days after the injection. Perilimbal suction cup studies showed 29.48 % reduction in aqueous flow. It is concluded that Na-K ATPase play an important role in the aqueous formation and that ouabain lowers the intraocular pressure by supressing this enzyme. Intravitreal administration has more powerful tension-lowering effect than intravenous injection.