Influences of glutathione and sulfhydryl containing compounds on aqueous humor outflow function

Several sulfhydryl reactive compounds have previously been shown to influence aqueous humor outflow facility. The purpose of the current study was to investigate the effect of glutathione depletion on certain of these sulfhydryl actions. Enucleated calf, monkey, and human eyes were perfused via the anterior chamber by the constant pressure (15 mmHg) technique. In calf eyes, perfusion of 10 mM cysteamine produced a small (-23%, P = 0.03) decrease in outflow facility that was also observed after hyaluronidase pretreatment. In contrast, following pretreatment with 1 mM BCNU [1,3 bis(2 chlorethyl)-1-nitrosourea], an inhibitor of glutathione reductase, and 10 mM diamide, a glutathione oxidant, which did not by themselves significantly affect outflow facility, perfusion of cysteamine resulted in an opposite effect--a remarkably large (+90%, P less than 0.001) increase in outflow facility. Other reduced and oxidized sulfhydryl-containing compounds such as cysteine, beta-mercaptoethanol, and glutathione, itself, as well as the non-sulfhydryl reducing agent, ascorbic acid, were substituted for cysteamine in this protocol and found to produce similar effects of varying magnitudes. In general, the reduced sulfhydryl containing compounds and ascorbic acid were the most effective. Pretreatment with BCNU alone without diamide did not produce this effect. Treatment with BCNU and diamide resulted in a greater than 75% decrease in reduced glutathione levels and a concomitant tenfold increase in glutathione mixed disulfide levels (0.229 vs. 0.030 mumol g-1 wet weight) in the calf trabecular meshwork. The subsequent perfusion with cysteamine reversed this mixed disulfide formation.(ABSTRACT TRUNCATED AT 250 WORDS)