Total iridectomy does not alter outflow facility responses to cyclic AMP in cynomolgus monkeys

Total outflow facility was measured by two-level constant pressure anterior chamber perfusion in surgically untouched and totally iridectomized cynomolgus monkey eyes receiving bolus intracameral infusions of cyclic AMP, dibutyryl cyclic AMP, or 5'AMP. Cyclic AMP doses of 50 and 100 micrograms (corresponding to initial intracameral concentrations of 1.5- and 3 mM) increased facility by approximately 20 and 40% respectively in both surgically untouched and aniridic eyes. Higher doses produced no greater effect, and lower doses were ineffective. Dibutyryl cyclic AMP and 5'AMP were ineffective in doses up to 100 micrograms (2- and 3 mM respectively). These findings indicate that the iris plays no mechanical role in mediating the facility response to cyclic AMP, and that the iridectomy procedure per se does not compromise the ability of the outflow pathways to respond to cyclic AMP. Since untouched and aniridic eyes exhibit similar facility responses to epinephrine and norepinephrine, the present findings also suggest that the iris is not the source of cyclic AMP mediating facility responses to catecholamines.