Effect of ouabain on aqueous humor formation rate in cats.

The effect of intravenous and intracameral ouabain on aqueous humor (AH) formation rates was measured in cats. AH formation rate was determined with continuous, posteroanterior chamber perfusion with an AH-like buffer containing trace quantities of inulin-C. After intravenous injection of 67 fig of ouabain per kilogram, there was a 40 per cent reduction in AH formation rate, while 34 fig per kilogram caused a 26 per cent reduction. There was no change after 10 fig of intravenous ouabain per kilogram. In other experiments, ouabain-containing buffer was substituted for the control buffer after a control period. No change in AH formation rates was noted after intracameral perfusion with 10-*M, 10~M, or 10~M ouabain. It is concluded that high doses of intravenous ouabain significantly decrease AH formation rates, probably by inhibition of ciliary body Na-K activated adenosine triphosphatase. There is no effect on AH formation rates by high and low doses of intracameral ouabain.